Compositions comprising surface modified globular nano-particles

Abstract

A dermatological composition comprising positively chargeable core-shell nano-elements composed of a water-insoluble biodegradable compound capable of stimulating collagen synthesis (CSSC) at their co

Description

FIELD The present disclosure relates to compositions suitable in particular for dermatological purposes, including to achieve cosmetic and non-cosmetic effects. Methods of prepar ing these compositions are also disclosed. BACKGROUND Skin plays an important role in protecting the body from hazards of the outer environment. It also displays the most visible signs of aging, such as drop in elasticity, tonicity and firmness leading to skin sagging, and such as superficial blemishes, or lesions, spanning from small lines to deep wrinkles. The skin changes as a result of intrinsic and extrinsic factors. Intrinsic aging factors include genetics, cellular metabolism, hormones and metabolic processes. Such factors can cause diminished production of collagen and elastin, proteins widely present in the skin to ensure its structural integrity, and reduced production of glycosaminoglycans (GAGs), which are water-binding molecules contributing, together with elastin and collagen, to the skin matrix. Diminished functioning of the sweat and oil glands is another intrinsic process, which may also contribute to the skin becoming thinner and more fragile with age. Extrinsic factors include chronic light exposure, smoking, pollution, ionizing radiation, chemicals, toxins etc. They usually lead to thickening of the outermost skin layer (stratum corneum), pre-cancerous changes, likely leading to skin cancer, freckles and sun spots formation, as well as excessive loss of collagen, elastin, and GAGs. Together or alone, these processes give the skin the appearance of deep wrinkles, uneven tone, roughness and thin skin. Collagen, elastin, and GAGs, which can be referred to as structural skin polymers, do not only provide for the mechanical properties of the skin, but also fulfill biological functions, both in healthy and pathological conditions. There are many approaches to reduce or delay skin aging, ranging from mild topical treatments to more extreme surgical ones. Early signs of aging can be treated with topical application of cosmetic products, including for example retinoids, vitamin C and a-hydroxy acids. Chemical peelings, dermabrasion, micro-needling, ultrasound energy devices, or laser resurfacing may be an option for moderate to severe skin damage. Deeper facial lines may be treated invasively, for instance by injecting botulinum toxin, dermal fillers, or a skin polymer being depleted by the aging process, such as collagen itself, the size of these molecules preventing their delivery through the skin. Surgical interventions, such as a face lift, brow lift, or cosmetic surgery on the eyelids, are the more extreme measures taken against wrinkles and skin sagging. Another approach used in anti-aging treatment of the skin involves increasing collagen synthesis in situ. There are many agents that are known to induce such synthesis, which can be administered orally, topically or parenterally. Orally-administered agents include food supplements such as vitamin C, ginseng, and nutrition-derived antioxidants (such as blueberries, cinnamon, certain herbs etc.\ among others. Aloe vera and retinol, are two of the agents known to boost collagen synthesis while applied topically on the skin. Hydroxyapatite, on the other hand, may achieve such an effect only if administered by injection. Topical compositions are considered more convenient for application, as well as safer and typically more effective in covering large areas, compared to compositions administered parenterally (involving pain and infection risks) or orally (where a first-pass metabolism should be overcome to retain efficacy). Hence, while injectable compositions having improved efficacy are still being sought, topical compositions are more desired, especially for anti-aging treatments, such as described above. However, to be able to permeate the skin, cosmetically-active agents (i.e., cosmeceuticals) or medically-active agents (i.e., pharmaceuticals) in such topical compositions should be small enough (typically having a molecular weight of 500 g / mol or less) to be able to penetrate the skin barrier and achieve a satisfactory transdermal delivery. Such agents are preferably in the form of nano-materials, e.g., nano-fibers, nano-emulsions, nano-spheres, nano-capsules, nano-crystals, dendrimers, liposomes, nanotubes, etc., such as described in a review by Souto E.B. et al / , “Nanomaterials for Skin Delivery of Cosmeceuticals and Pharmaceuticals”; Applied Sciences, 2020, Vol. 10(5), 1594. Besides the above exemplary compounds, known to boost synthesis of structural skin proteins, polymers (including proteins, and their fragmented / shorter versions known as peptides) have also been reported to promote the production of collagen, elastin, GAGs or other such molecules involved in maintaining the skin structural and functional integrity. Other polymers (or the same) may (alternatively or additionally) inhibit processes or enzymes (e.g., proteases) leading to the deterioration of natural skin proteins. For illustration, some peptides have been reported to boost collagen neo-synthesis, while others have been reported to inhibit collagenase, the enzyme responsible for collagen degradation. Regardless of the type of biological activity, such materials (whether polymers or not) may have - positively stimulating neo-synthesis of structural skin proteins and / or negatively inhibiting down-regulators of such skin proteins - the end-result may range from reducing or delaying the diminution of skin proteins’ amount, maintaining their level, or even increasing their presence. Such agents may be referred to herein as collagen-synthesis stimulating compounds (CSSC), or specifically as collagen-synthesis stimulating polymers (CSSP), the activity of such agents with respect to collagen including not only the stimulation of its neo-synthesis but alternatively or additionally the prevention of its degradation. As dermatological - pharmaceutical or cosmetic - products are constantly required in order to maintain skin integrity (function and / or structure) for as long as possible, protecting from environmental factors such as UV or toxic oxygen products, reducing dry skin conditions or fighting the cutaneous signs of ageing, there remains a need to provide dermatological compositions that resolve at least some of the problems described above. Advantageously, the novel compositions would permit transdermal transfer of molecules having a high molecular weight, whose conventional delivery would otherwise require injection. SUMMARY Aspects of the invention relate to dermatological compositions comprising core-shell nano-elements composed of a core including a water-insoluble collagen-synthesis stimulating compound (CSSC), such as a collagen-synthesis stimulating polymer (CSSP), and a shell including at least one fatty amine, dispersed as nano-particles or nano-droplets in a polar carrier. Notably, the CSSC or CSSP molecules (which can be functionalized to enhance any of their desired properties) may have a molecular weight of 0.6 kDa or more. The nano-elements may further contain a second shell, formed of an active cosmetic or pharmaceutical agent, the second shell surrounding the fatty amine shell. Methods for preparing the core shell(s) nano-elements are also disclosed. The compositions, which typically include at least one surfactant with the CSSC, the carrier, or both, may optionally contain, in addition to the CSSCs or CSSPs, at least one active agent, such as specified herein-below. While these dermatological compositions have been developed in order to overcome, inter alia, at least some of the drawbacks associated with present delivery of CSSC(s) (e.g., CSSP(s)) and / or particular active agent(s) to the skin, transdermal delivery by topical application being preferred, their suitability for parenteral delivery by injection is not ruled out. Also disclosed are methods for preparing such topical or injectable dermatological compositions as well as uses thereof. In a first aspect of the disclosure, there is provided a dermatological composition comprising core-shell nano-elements (i.e., nano-particles or nano-droplets) composed of: a) a core comprising a water-insoluble biodegradable collagen-synthesis stimulating compound (CSSC) having a molecular weight of 0.6 kDa or more; and b) a shell surrounding the core, the shell comprising a water-insoluble fatty amine, non-covalently bonded to the CSSC; the core-shell nano-elements being dispersed in a polar carrier and positively chargeable in water; wherein at least 50% of the total number of the core-shell nano-elements have an average diameter (e.g.. Dn50) of 200 nanometer (nm) or less. The non-covalent association of the shell to the core is believed to advantageously maintain the original activity of each of the molecules of the core and the shell, none of their moieties being involved in covalent binding through electron sharing that could have reduced or modified their respective contribution to the potency of the composition. Moreover, the fact that the fatty amines are not covalently bound to the CSSCs allow them to migrate to the outer surface of the nano-elements to form a shell thereon. In some embodiments, the CSSC has a native viscosity of 107 millipascal-second (mPa s) or less, 106 mPa s or less, 105 mPa s or less, 104 mPa s or less, or 103 mPa s or less, as measured at 50°C and a shear rate of 10 sec'1. In other embodiments, the native viscosity of the CSSC, typically a CSSP, is higher than 107 mPas under the aforesaid measuring conditions, being for instance of up to 1011 mPa s, in which cases the CSSC can be combined with at least one plasticizing agent. In some embodiments, the fatty amines, in addition to their role in forming the shell of the nano-elements, may also serve as a plasticizing agent capable of reducing the native viscosity (also referred to as a first viscosity) of the CSSC of the core and facilitating its processing and incorporation as nano-elements into the present dermatological composition. In other embodiments, reduction of viscosity of the CSSC, if desired, is obtained by adding a nonvolatile liquid to the core to act as a plasticizing agent. Hence, in some embodiments the fatty amine(s) included in the composition and the nonvolatile liquid(s) optionally added to act as a plasticizing agent are present in a respective amount suitable if combined to at least lower the first (native) viscosity of the CSSC to a second (plasticized) viscosity' of no more than 107 mPas, as measured at 50°C and a shear rate of 10 sec'1. In some embodiments, the CSSC having been plasticized by the fatty amine(s) and / or by the non-volatile liquid(s) (herein referred to as a “plasticized” or “swelled” CSSC) exhibits a “second” viscosity being reduced as compared to the first viscosity, the second viscosity of the CSSC being of 106 mPa s or less, 105 mPa s or less, 104 mPa s or less, or IO3 mPa s or less, as measured at a temperature of 50°C and a shear rate of 10 sec'1. In a second aspect of the disclosure, there is provided a dermatological composition comprising core-shell nano-elements dispersed in a polar carrier, the nano-elements being composed of: i. a core comprising a water-insoluble biodegradable CSSC, plasticized by a non-volatile liquid, the CSSC having an average molecular weight of 0.6 kDa or more; ii. a shell surrounding the core, the shell comprising a water-insoluble fatty amine, non-covalently bonded to the CSSC; the core-shell nano-elements being dispersed in a polar carrier and positively chargeable in water; wherein at least 50% of the total number of the core-shell nano-elements have an average diameter (e.g., Dn50) of 200 nm or less. hi some embodiments, the CSSC (and / or the plasticized CSSC) is characterized by at least one, at least two, or at least three of the following structural properties: i. the CSSC and / or the plasticized CSSC is insoluble in the polar carrier; ii. the CSSC and / or the plasticized CSSC has at least one of a melting temperature (Tm), a softening temperature (Ts), or a glass transition temperature (Tg) of at most 300°C, at most 250°C, at most 200°C, at most 180°C, at most 150°C, or at most 120°C, said temperatures being either a first (i.e., native) Tm, Ts or Tg of the CSSC, or a second Tm, Ts or Tg of the CSSC if plasticized, or both; iii. the CSSC has a first and / or second Tm or Ts of at least 20°C, at least 30°C, at least 40°C, at least 50°C, or at least 60°C; iv. the CSSC has a first and / or second Tg of -75°C or more, -50°C or more, -25°C or more, 0°C or more, 20°C or more, 30°C or more, 40°C or more, 50°C or more, or 60°C or more; v. the CSSC has at least one of a first and / or second Tm. Ts and Tg between 20°C and 300°C, between 20°C and 250°C, between 20°C and 200°C, between 30°C and 180°C, between 40°C and 180°C, or between 50°C and 150°C; vi. the CSSC has a molecular weight of 0.7 kDa or more, 0.8 kDa or more, 0.9 kDa or more, 1 kDa or more, 2 kDa or more, or 5 kDa or more; vii. the CSSC has a molecular weight of 500 kDa or less, 300 kDa or less, 200 kDa or less, 100 kDa or less, 80 kDa or less, 50 kDa or less, 25 kDa or less, or 15 kDa or less; and viii. the CSSC has a molecular weight between 0.6 kDa and 500 kDa, between 0.7 kDa and 300 kDa, between 0.8 kDa and 200 kDa, between 1 kDa and 100 kDa, or between 2 kDa and 80 kDa. In some embodiments, the at least one structural property fulfilled by at least one of the CSSC and the plasticized CSSC is: property i) as above listed, property ii) as above listed, property' iii) as above listed, property iv) as above listed, property v) as above listed, property vi) as above listed, property' vii) as above listed, or property viii) as above listed. In some embodiments, the at least two structural properties fulfilled by at least one of the CSSC and the plasticized CSSC are: properties i) and v), properties i) and viii), or properties v) and viii), of the above-listed properties. In some embodiments, the at least three structural properties fulfilled by at least one of the CSSC and the plasticized CSSC are: properties i), ii) and v); properties i), ii) and viii); properties i), iii) and viii); properties i), iv) and viii); properties i), v) and vi); properties i), v) and vii); or properties i), v) and viii), of the above-listed properties. hi particular embodiments, the CSSC is a CSSP, the chemical compound being a polymer formed of repeating structural units, such monomers being either same (forming homopolymers) or different (forming random or block copolymers). In another particular embodiment, the polymer of the CSSP is a thermoplastic polymer. While non polymeric compounds typically have molecular weights of up to 2 kDa, generally not exceeding 1 kDa, CSSPs can be larger molecules of at least a few kDas. As used herein, the term “nano-elements”, as used with respect to the core-shell structures containing inter alia the CSSC (plasticized or not), refers to relatively solid nano-particles or relatively liquid nano-droplets having an average diameter of 200 nrn or less, 150 nm or less, 100 nm or less, 75 nm or less, or 50 nm or less, such structures being dispersed (e.g., as a result of nano-sizing) in a homogeneous medium, forming therein a nano-suspension. Such core-shell nano-elements have typically an average diameter of 2 nm or more, 5 nm or more, 10 nm or more, 15 nm or more, or 20 nm or more. In some embodiments, the average diameter of the core-shell nano-elements of the compositions according to the present teachings is between 2 nm and 200 nm, between 5 nm and 150 nm, between 10 nm and 100 nm, between 15 nm and 75 nm, or between 20 nm and 50 nm. The average diameter of the core-shell nano-elements can be determined by any suitable method and may refer to the hydrodynamic diameter of the elements as measured by Dynamic Light Scattering (DLS) and established for 50% of the nanoelements by number (Dn50). hi view of their intended use and / or method of preparation, CSSCs suitable for the present invention are advantageously relatively solid at room temperature (circa 20°C) and up to body temperatures (e.g., circa 37°C for human subjects). Such preferences are extended to the plasticized CSSC, which further takes into account the fatty amine(s) and / or non-volatile liquid(s) and their relative amounts, or the presence of any other material affecting the thermal behavior of the product. As can be appreciated by persons skilled in the art, as the CSSCs can be thermoplastic polymers, a “relative solidity” of such materials, or such materials being “relatively solid”, at any particular temperature is referring to the fact that they are not necessarily solid but display a viscoelastic behavior. Without wishing to be bound by any particular theory, such feature of the CSSCs should ensure, to the extent necessary, that the nano-elements made therefrom are relatively non-sticky, facilitating their even distribution in a composition according to the present teachings. From the standpoint of transdermal delivery, it is believed that the relatively malleable / deformable nature of the core (whether intentionally plasticized or not to have a suitable viscosity as herein disclosed) facilitates the transfer of the nano-elements through the skin, the pathways across the stratum comeum, or down hair follicles or sweat glands being often narrow and tortuous. The dermatological compositions of the present invention are in the form of a nanosuspension. Depending on the Tm or Ts of the CSSCs (either plasticized or having the desired viscosity in their native form), the composition can be at room temperature in the form of a nano-dispersion (i.e.. if the Tm or Ts is above 20°C, e.g.., between 25°C and 80°C), the core-shell nano-elements being relatively solid nano-particles, or in the form of a nano-emulsion {i.e.. if the Tm or Ts is below 20°C), the core-shell nano-elements being relatively liquid nanodroplets. In some embodiments, the CSSC is plasticized and it exhibits (alone or in combination with any material added thereto as a mixture) at least one of a second Tm, Ts, or Tg, lower than the first respective Tm, Ts, or Tg of the unplasticized native CSSC, at least one of the second Tm, Ts, or Tg being 0°C or more, 10°C or more, 20°C or more, 30°C or more, 40°C or more, 50°C or more, or 60°C or more. In other embodiments, the at least one of a second Tm, Ts, or Tg of the plasticized or swelled CSSC is at most 290°C, at most 250°C, at most 200°C, at most 190°C, at most 180°C, or at most 170°C. In some embodiments, the plasticized or swelled CSSC, and / or the mixture comprising it, has at least one of a second Tm, Ts, or Tg being in a range from 0°C to 290°C, from 10°C to 250°C, from 20°C to 200°C, from 30°C to 190°C, from 40°C to 180°C, or from 50°C to 170°C. In some embodiments, the CSSC is a quinone, hi particular ubidecarenone, also called 1,4-benzoquinone or coenzyme Q10 (CoQlO). In other embodiments, the CSSC is a CSSP, the polymer being selected from a group of polymer families comprising: aliphatic polyesters, such as polycaprolactone (PCL), polylactic acid (PLA), poly(L-lactide) (PLLA), poly(D-lactide) (PDLA), poly(D,L-lactide) (PDLLA), polyglycolic acid (PGA), poly(p-dioxanone) (PPDO) and poly(lactic-co-glycolic acid) (PLGA); polyhydroxy-alkanoates, such as polyhydroxybutyrate (PHB), poly-3-hydroxy-butyrate (P3HB), poly-4-hydroxy-butyrate (P4HB), polyhydroxy-valerate (PHV), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polyhydroxy-hexanoate (PHH) and poly hydroxy octanoate (PHO); poly(alkene dicarboxylates), such as poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBSA) and poly(ethylene succinate) (PES); polycarbonates, such as poly-(trimethylene carbonate) (PTMC), polypropylene carbonate) (PPC) and poly[oligo-(tetramethylene succinate)-co(tetramethylene carbonate); aliphatic-aromatic co-polyesters, such as poly(ethylene terephtalate) (PET) and poly(butylene adipate-co-terephtalate) (PBAT); isomers thereof, copolymers thereof and combinations thereof In particular embodiments, the CSSC is CoQlO or a CSSP being an aliphatic polyester. In a further particular embodiment, the aliphatic polyester of the CSSP is selected from polycaprolactone, polylactic acid, isomers thereof, copolymers thereof and combinations thereof hi some embodiments, the non-volatile liquid that may be added to the CSSC to lower at least one of its first (native) viscosity, Tm, Tg and Ts is selected from a group comprising: monofunctional and poly functional aliphatic esters, fatty esters, cyclic organic esters, fatty acids, terpenes, aromatic alcohols, aromatic ethers, aldehydes and combinations thereof In particular embodiments, the non-volatile liquid is selected from: dibutyl adipate, C12-C15 allcyl benzoate and dicaprylyl carbonate. In some embodiments, the water-insoluble fatty amine is a primary, a secondary or a tertiary Cs-2o straight, branched, or cyclic, saturated or unsaturated alkyl amine, including combinations thereof. In some embodiments, the water-insoluble fatty amine is selected from a group consisting of oleyl amine, N,N-Bis-(2-hydroxyethyl)Ci2-Ci8-alkylamine, octyl amine, N,N-dimethyl-dodecylamine (DMDA), cetrimonium chloride (cetyltrimethylammonium chloride (CTAC)) and combinations thereof. In some embodiments, the polar carrier in which the core-shell nano-elements comprising the CSSC are dispersed includes water, glycols (e.g., propylene glycol, 1,3-butanediol, 1,4-butanediol, 2-ethyl-l,3-hexanediol and 2-methyl-2-propyl-l,3-propanediol), glycerol, precursors and derivatives thereof, collectively termed herein “glycerols”, (e.g., acrolein, dihydroxyacetone, glyceric acid, tartronic acid, epichlorohydrin, glycerol tertiary butyl ether, polyglycerol, glycerol ester and glycerol carbonate) and combinations thereof. In a particular embodiment, the polar carrier comprises water, consists of water or is water. In some embodiments, the chemical identity and respective amounts of the materials constituting the core and the materials constituting the shell are such that the core-shell nanoelements formed thereby have a charge of +5 mV or more, +10 mV or more, +20 mV or more, +30 mV or more, or +40 mV or more, as measured at room temperature in water or in an aqueous polar carrier. As known to persons skilled in the measurement of charge and zeta potential of compositions, it is stressed that in this particular context an aqueous polar carrier need only to contain an amount of water (e.g., >5 wt.%) sufficient to promote the protonation of the fatty amines of the shell. Such values, which can be measured with any suitable equipment, can be determined in the composition “as is” or in a diluted sample thereof. Depending on the nature of the amine groups of the fatty amines, the pH providing optimal charging may vary, and the aforesaid positive charges of the nano-elements can be observed at at least one pH in the range of pH 1 to pH 10. In some embodiments, the fatty amine, in addition to its role in forming the shell and optional role as a plasticizing agent, may also serve as a surfactant for the purpose of stabilizing the core-shell nano-elements within the nano-suspension. In some embodiments, the dermatological (e.g., topical) composition further comprises at least one surfactant, selected from an emulsifier and a hydrotrope. The surfactant(s) may be present in the core-shell nano-elements containing the CSSC (e.g., if being polar-carrier-insoluble surfactant(s)), in the liquid phase containing the polar carrier (e.g., if being polar-carrier-soluble surfactant(s)), or in both (e.g., if being intermediate emulsifiers). In some embodiments, the at least one surfactant is an emulsifier selected from a group comprising alkyl sulfates, sulfosuccinates, alkyl benzene sulfonates, acyl methyl taurates, acyl sarcocinates, isethionates, propyl peptide condensates, monoglyceride sulfates, ether sulfonates, ester carboxylates, fatty acid salts, quaternary ammonium compounds, betaines, alkylampho-propionates, alkyliminopropionates, alkylamphoacetates, fatty alcohols, ethoxylated fatty alcohols, poly (ethylene glycol) block copolymers; ethylene oxide (EO) / propylene oxide (PO) copolymers, alkylphenol ethoxylates, alkyl glucosides and poly glucosides, fatty alkanolamides, ethoxylated alkanolamides, ethoxylated fatty acids, sorbitan derivatives, alkyl carbohydrate esters, amine oxides, ceteareths, oleths, alkyl amines, fatty esters esters, polyoxylglycerides, natural oil derivatives, ester carboxylate and urea. hi some embodiments, the at least one surfactant is a hydrotrope selected from a group comprising sodium dioctyl sulfosuccinate, urea, sodium tosylate, adenosine triphosphate, cumene sulfonate and salts (e.g., sodium, potassium, calcium, ammonium) of toluene sulfonic acid, xylene sulfonic acid and cumene sulfonic acid. In some embodiments, the dermatological (e.g., topical) composition further comprises at least one skin-penetration enhancer. Such agents are typically found in the liquid phase in which the nano-elements containing the CSSC are dispersed. In some embodiments, the dermatological (e.g., topical) composition further comprises an active agent within the core including the CSSC, the active agent being substantially insoluble in the polar carrier (hence, referred to as a “carrier-insoluble active agent”). The carrier-insoluble active agent can be a blend of different agents, each having a same or different activity In some embodiments, the dermatological (e.g., topical) composition further comprises an active agent forming a second shell on the surface of the core-shell nano-elements, the active agent being soluble in the polar carrier (hence, referred to as a “carrier-soluble active agent”).. In some embodiments, the second shell is composed of at least one layer of the carrier-soluble active agent. Nano-elements comprising a core of CSSC (optionally including polar-carrier insoluble surfactant(s) and / or carrier-insoluble active agent(s)), a first shell of fatty amine(s) and a second shell being at least one layer of a carrier-soluble active agent, can be referred to as core-shells or as core-multi-shells nano-elements. Advantageously, the first shell of a core-multi-shells nano-element which is positively charged in an aqueous polar carrier of the composition facilitates the non-covalent formation of the second shell, for instance by electrostatic interactions with carrier-soluble active agents having a negative charge in the polar carrier. In such case, the nano-elements which were formerly positively charged with a single shell of fatty amines may become less positively charged, electrostatically neutral, or negatively charged. Additionally, or alternatively, the first shell of fatty amines can form covalent bounds with the second shell of carrier-soluble active agents facilitating their attachment to the core. Preferably, the covalent or non-covalent wrapping of the second shell around the first shell is such that the nano-elements do not increase in size beyond the size ranges herein disclosed as suitable when transdermal delivery is envisioned. In some embodiments of each of the first and second aspects, the core-shell nanoelements have a first surface zeta potential (£1), and the carrier-soluble active agent has a second zeta potential (£2) such that an absolute value of a zeta potential differential (AQ defined as AC = |^2 - is at least 5 mV, as measurable in the presence of water. Such values can be determined as described for the charge of the core-shell nano-elements, the conditions (e.g., equipment, temperature and pH) selected for the measurements being the same for the nanoelements and the carrier-soluble active agent. As used herein, a material is deemed to be insoluble in a liquid carrier, being for instance a “polar-carrier-insoluble active agent” (or a “carrier-insoluble active agent”), if having a solubility' within the carrier it is immersed in of less than 5 wt.% (and more typically, less than 4 wt.%, less than 3 wt.%, less than 2 wt.%, less than I wt.%, or less than 0.5%) by weight of the polar carrier, at a temperature of 20°C. Conversely, a material is deemed to be soluble in a liquid carrier, being for instance a “polar-carrier-soluble active agent” (or a “carrier-soluble active agent”), if having a solubility within the carrier it is immersed in of 5 wt.% or more (and more typically, 6 wt.% or more, 7 wt.% or more, 8 wt.% or more, 9 wt.% or more, or 10 wt.% or more) by weight of the polar carrier, at a temperature of 20°C. As appreciated by a skilled person some materials having a sought activity can be polar-carrier-insoluble in one chemical form, and polar-carrier-soluble in another, salts of a material typically increasing its solubility. In some embodiments, the dermatological (e.g., topical) compositions comprise more than one active agent in addition to the CSSC, the active agents being either in same or different phase. For illustration, a first active agent, being carrier-insoluble, can be contained within the cores of the nano-elements and a second active agent, being carrier-soluble, can form the second shell surrounding a first shell of fatty amines. In some embodiments, the at least one carrier-insoluble active agent is selected from a group comprising: benzoyl peroxide, erythromycin, macrolides, retinol, salicylic acid, tetracyclines, tretinoin, vitamin A, vitamin D, vitamin K and plant extracts insoluble in the polar carrier, such active agents having inter alia anti-acne, anti-oxidant, anti-inflammatory, and / or anti-aging activity beneficial to the skin. In particular embodiments, the carrier-insoluble active agent that can be incorporated in the nano-elements of CSSC is retinol. In some embodiments, the at least one carrier-soluble active agent is selected from a group comprising: azelaic acid, biotin, clindamycin, collagen, elastin, folacin, hyaluronic acid (HA), niacin, pantothenic acid riboflavin, thiamin, vitamin B12, vitamin B6, vitamin C and plant extracts soluble in the polar carrier, such active agents having anti-acne, anti-oxidant, antiinflammatory, and / or anti-aging activity beneficial to the skin. Advantageously, the dermatological (e.g., topical) compositions of the present invention can have a relatively high concentration (e.g, 1 wt.% or more) of a CSSC {e.g., a CSSP) and / or of an optional active agent (e.g., retinol within the core or HA in a second shell, surrounding the core first shell), and / or the CSSC(s) and / or optional active agent(s) can have a relatively high molecular weight, as compared to conventional topical compositions comprising such ingredients. Without wishing to be bound by theory, the relatively higher loading of the CSSC(s) and / or optional active agent(s), and / or the relatively higher potency thereof (when MW-dependent), is expected to provide a higher gradient of concentration, favoring transdermal delivery, and ultimately cosmetic or pharmaceutic efficacy. It is noted that nano-particles or nano-droplets of a CSSC having a particle size within the range of dimensions disclosed herein was found unexpectedly successful by the Inventors, as such forms of the CSSCs, in particular if being plasticized CSSPs, were expected to aggregate in view of their anticipated stickiness. In a third aspect of the disclosure, there is provided a method for preparing a dermatological composition comprising core-shell nano-elements dispersed in a polar carrier, the core-shell nano-elements comprising a water-insoluble CSSC in the core, the method comprising the steps of: a) providing a water-insoluble CSSC, wherein: i. the CSSC is biodegradable; ii. the CSSC has a molecular weight of at least 0.6 kDa; iii.the CSSC has at least one of a first Tm, Ts, or Tg of 300°C or less; and iv. The CSSC has a first viscosity optionally higher than 107 mPas, as measured at 50°C and a shear rate of 10 sec'1; b) mixing the CSSC with a water-insoluble fatty' amine and a non-volatile liquid miscible with the CSSC, the mixing being at a mixing temperature equal to or higher than the at least one first Tm, Ts, or Tg of the CSSC, whereby a homogeneous mixture of plasticized CSSC and fatty amine is formed, the plasticized CSSC having a second Tm, Ts, or Tg lower than the respective first Tm, Ts, or Tg, and a second viscosity lower than the first viscosity, the second viscosity being of 107 mPa s or less, as measured at 50°C and a shear rate of 10 sec'1; c) combining the mixture of step b) with a polar carrier; and d) nano-sizing the combination of step c) by applying shear at a shearing temperature equal to or higher than at least one of the second Tm, Ts, or Tg of the plasticized CSSC, so as to obtain a nano-suspension, whereby core-shell nano-elements, composed of a core containing the plasticized CSSC and a shell containing the water-insoluble fatty amine surrounding the core, are dispersed in the polar carrier; the nano-elements having an average diameter (e.g., Dn50) of 200 nm or less. hi some embodiments of the third aspect, the mixing temperature in step b) is higher than the at least one first Tm, Ts, or Tg of the CSSC by 5°C or more, 10°C or more, 20°C or more, 30°C or more, or 40°C or more, as long as the mixing is performed at a temperature at which an insignificant part of the fatty amine, as well as of the non-volatile liquid is boiled away. Assuming that the fatty amine has a boiling temperature Tba and the non-volatile liquid has a boiling temperature Tbi at the pressure of the mixing step, then in some embodiments the mixing temperature can additionally be lower than the lowest of the boiling temperatures Tba of the fatty amine and the Tbi of the non-volatile liquid. When the duration of mixing is sufficiently brief and / or the fatty amine and / or non-volatile liquid are in sufficient excess, the mixing temperature can alternatively be at boiling temperatures Tba, Tbi or above. In a fourth aspect of the disclosure, there is provided a method for preparing a dermatological composition comprising core-shell nano-elements dispersed in a polar carrier, the core-shell nano-elements comprising a water-insoluble CSSC in the core, the method comprising the steps of: a) providing a water-insoluble CSSC, wherein: i. the CSSC is biodegradable; ii. the CSSC has a molecular weight of at least 0.6 kDa; iii. the CSSC has at least one of a first Tin, Ts, or Tg of 300°C or less; and iv. the CSSC has a first viscosity of 107 mPa s or less, as measured at 50°C and a shear rate of 10 sec'1; b) mixing the CSSC with a water-insoluble fatty amine, the mixing being at a mixing temperature equal to or higher than the at least one first Tm, Ts, or Tg of the CSSC, whereby a homogeneous mixture of the CSSC and fatty amine is formed; c) combining the mixture of step b) with a polar carrier; and d) nano-sizing the combination of step c) by applying shear at a shearing temperature equal to or higher than the at least one first Tm, Ts, or Tg of the CSSC, so as to obtain a nanosuspension, whereby core-shell nano-elements, composed of a core containing the CSSC and a shell containing the water-insoluble fatty amine, the shell surrounding the core, are dispersed in the polar carrier; the nano-elements having an average diameter (e.g., Dn50) of 200 nm or less. While the fatty amines are thoroughly mixed with the CSSC or the CSSC plasticized with a non-volatile liquid, they are believed to migrate towards the outer surface of the nanoelements, allowing their hydrophilic heads to be exposed to the polar carrier surrounding the nano-elements, while their hydrophobic tails tend to remain within the water-insoluble environment of the core. This phenomenon results in the formation of the shell, which can be confirmed by the change in charge of the nano-elements. While a core of CSSC deprived of a shell of fatty amines would display a negative charge in an aqueous polar liquid (e.g., in water), the formation of a shell of fatty amines as obtained by the above method masks the core, reducing its negative charge, and may even provide a positive charge to the core-shell nano-elements depending on the respective charge density' and amounts of the core and shell materials. Noticeably, the fatty amines forming the shell are not covalently bound to the CSSC of the core, enabling the fatty amines to migrate to form the shell and the materials of the core and the shell to retain their original respective potency. In some embodiments of each of the third and fourth aspects, the shearing temperature is higher than the second Tm, Ts, or Tg of the plasticized CSSC (or higher than the first Tm, Ts, or Tg, in case of an un-plasticized CSSC) by 5°C or more, 10°C or more, 20°C or more, 30°C or more, or 40°C or more, as long as the nano-sizing is performed at a temperature at which an insignificant part of the polar carrier is boiled away. Assuming that the polar carrier has a boiling temperature Tbc at the pressure of the nano-sizing step, then in some embodiments, the shearing temperature can additionally be lower than the boiling point Tba of fatty amine, and / or the boiling point Tbi of the non-volatile liquid (if added) and / or lower than the boiling point Tbc of the polar carrier, under the pressure at which the nano-sizing step is performed, by 5 °C or more, 10°C or more, 20°C or more, 30°C or more, or 40°C or more. When the duration of nanosizing is sufficiently brief and / or the polar carrier in sufficient excess, the nano-sizing temperature can alternatively be at boiling temperature Tbc or above. In some embodiments of each of the third and fourth aspects, the obtained nanosuspension is a nano-emulsion, and the method comprises an additional step, wherein the obtained nano-emulsion is cooled to a temperature lower than at least one of the first or second Tm, Ts, or Tg of the CSSC. While such cooling may passively occur upon termination of nanosizing, the temperature of the nano-suspension naturally decreasing over time to room temperature, in some embodiments, the cooling is performed by actively lowering the temperature of the nano-emulsion by any suitable cooling method. Additionally, or alternatively, the cooling is performed under continued shearing or any other method maintaining the agitation of the composition. While the composition may remain a nanoemulsion following its active or passive cooling, in some embodiments, the composition can then form a nano-dispersion. In some embodiments of the third and fourth aspects, a surfactant is added during step b) and / or during step c), the surfactant being either an emulsifier or a hydrotrope, as herein described. In some embodiments of the third and fourth aspects, the polar carrier is not water, and the method further comprises a step of replacing at least part of the polar carrier by water. In some embodiments of each of the third and fourth aspects, the method further comprises combining at least one polar-carrier-insoluble active agent with the CSSC(s) and water-insoluble fatty amine(s) (including the optional non-volatile liquid(s) and / or surfactant(s) if present), said combination being performed a) whilst mixing the CSSC with a water-insoluble fatty amine and, if applicable, a non-volatile liquid and / or at least one surfactant; b) by mixing the polar-carrier-insoluble active agent with the plasticized CSSC (when applicable) prior to combining it with the polar carrier; or c) whilst mixing the CSSC (optionally plasticized), previously combined with the fatty amine, with the polar carrier or nano-sizing the compositions components, the polar-carrier-insoluble active agent(s) being either in the nanoelements (if added as in a) or b)) or separately dispersed in the polar liquid phase (if added as in c)). In some embodiments of each of the third and fourth aspects, the method further comprises adding at least one polar-carrier-soluble active agent to the nano-suspension of coreshell nano-elements obtained in step d) and mixing the two, whereby a second shell, comprising the carrier-soluble active agent, is formed on the surface of the core-shell nano-elements. Such nano-elements can be referred to as active agent-coated core-shell nano-elements, core-shells nano-elements, or core-multi-shells nano-elements. The addition of such active agents can be performed at various steps during the preparation of the dermatological composition, depending on the resistance of the active agent to temperatures, mixing or shearing conditions applied at the envisioned step. Relatively resistant active agents can be added a) whilst combining the CSSC (or the plasticized CSSC) and fatty amine mixture with the polar carrier; or b) whilst nano-sizing the compositions components so as to obtain the core-shell nano-elements including the CSSC and water-insoluble fatty' amine. Alternatively, the active agent(s) which are soluble in the polar carrier, in particular if shear-sensitive, can be added to the obtained nano-suspension, agents being relatively heat-sensitive being preferably combined with the nano-emulsion or nano-dispersion after cooling. In some embodiments of the third and fourth aspects, the formation of the second shell requires the core-shell nano-elements to be positively charged, so that the polar-carrier-soluble active agent, being negatively charged, can be electrostatically attracted to them, arranging around the core-shell nano-elements and engulfing them. When the core-shell nano-elements have a negative charge or an insufficiently positive charge in the polar carrier, the method may further comprise adding a pH-modifying agent, in an amount suitable to increase the charge of the core-shell nano-elements (e.g., raising a positive charge), while retaining the negative charge of the carrier-soluble active agent. Depending on the functional groups present on the fatty amine molecules of the first shell, the pH-modifying agent may be either an acid or a base, an acidic pH-modifying agent being generally preferred. In some embodiments, the pH-modifying agent is added in an amount resulting in the composition having a pH between 1 and 10, between 1 and 9, or between 1 and 8. In particular embodiments, the pH modifying agent is added in an amount leading the composition to have a pH of 7 and less, 6 or less, 5 or less, or 4 or less. hi some embodiments of each of the third and fourth aspects, the method further comprises combining a first active agent, being insoluble in the polar carrier, with the CSSC and fatty amine, the combination being performed as aforesaid, and adding to the polar carrier a second active agent, being carrier-soluble, as aforesaid, the dermatological composition prepared thereby including a first active agent in the core of the nano-elements containing the CSSC and a second active agent forming the second shell of the nano-elements surrounding the first shell of fatty amines. In some embodiments of each of the third and fourth aspects, the method further comprises adding a skin-penetration enhancer to the polar carrier phase of the nano-suspension. The addition of such a skin-penetration enhancer can be performed at various steps during the preparation of the dermatological composition, and typically as above described for the sake of incorporating an active agent soluble in the polar carrier. In some embodiments of each of the third and fourth aspects, the CSSC, the waterinsoluble fatty amines, the polar carrier, and if desired for the preparation of the dermatological composition, the non-volatile liquid, the surfactant, the skin-penetration enhancer, the carrierinsoluble active agent and the carrier-soluble active agent, are substantially as described above and herein detailed. It is noted in this context that while compounds have been for simplicity categorized according to their main role in the present invention, in particular with respect to the preparation methods, such functions are not exclusive one of the other. For illustration, a fatty amine, typically serving to create the first shell, may also be capable of plasticizing the CSSC, and the fatty amine and / or the non-volatile liquid may also serve as a surfactant for the nano-elements. A polar carrier (e.g.. glycols), serving as liquid medium for the dispersed nano-elements, or a surfactant (e.g., urea) intended to increase the dispersibility of the nano-elements, may additionally serve as a skin-penetration enhancer once the composition is applied on the skin. The predominance of one role over the other may depend upon a material inherent potency in the respective fields, but also on the relative presence of the material in the composition. For instance, a material deemed a carrier if constituting a significant enough part (e.g., more than 20 wt.%) of the liquid phase, may be considered to fulfil a distinct function if in a relatively lower amount, such amount being more adapted to its secondary roles. In some embodiments, the dermatological compositions of the present invention can be prepared according to the methods herein disclosed and may further contain any additive conventionally present in such compositions. In a fifth aspect of the disclosure, there are provided uses for the present dermatological compositions, said uses being for improving skin appearance (as inter alia resulting from stimulating the neo-synthesis of skin structural proteins and / or for preventing their degradation). Such uses may have cosmetical or pharmaceutical effects on the skin, which is generally, but not necessarily, of a mammalian subject (e.g., a human person). While the present dermatological compositions may be injected where needed under the skin, their main use is for application onto the skin, allowing for the transdermal delivery of the CSSC (and of any other active agent present in the composition). Advantageously, transdermal delivery typically occurs over larger skin areas than permitted when a same product is injected locally. Hence, the effect of a CSSC (or other active agent) delivered transdermally using compositions according to the present teachings is expected to be wider with respect to the area being treated, generally providing for a more uniform effect over a larger surface. The composition can be applied topically to the skin where it may serve as a cosmetic composition (e.g., to improve appearance, as an anti-aging treatment, a skin protective treatment, a skin filling treatment, a skin smoothing treatment, and the like) or as a pharmaceutical composition (e.g., to relieve or treat a disorder). While for simplicity the effect of the present compositions, when deemed cosmetical, is referred to as “anti-aging”, for delaying, reducing, or preventing skin aging, this should not be construed as limiting, as processes similar to those leading to natural time-dependent skin aging are encountered in additional circumstances, such as degenerative disorders, or benign and malignant neoplasms, to name a few. Therefore, while for brevity the present invention is detailed for its cosmetic role and improvement of skin appearance (or postponement and / or diminution of deterioration of look), the compositions and the methods of preparation disclosed herein can have a broader beneficial impact, at least in the realm of dermatological treatment of conditions wherein one or more of the structural skin proteins that can be restored by the present compositions are pathologically reduced. Thus, use of a dermatological composition comprising core-shell nano-elements comprising a core composed of water-insoluble CSSC and a shell formed of fatty amines, the nano-elements being dispersed in a polar carrier as herein-disclosed (optionally prepared by the methods of the present teachings) should be broadly understood as use of a cosmetical or a pharmaceutical composition achieving any desirable cosmetic or pharmaceutic improvement of the skin. Such effects, for which the present compositions can be beneficial, are generally manifested by unproved skin appearance (use of the composition for, e.g, reducing the number of wrinkles and / or fine lines, improving skin elasticity, improving skin tonicity, combating wizened skin, combating flaccid skin, combating thinned skin, combating skin pigmentation, accelerating wound healing, promoting skin integrity, alleviating pain due to skin lesions, etc.) regardless of the cause of the phenomenon being treated by the composition. hi other embodiments, the dermatological compositions of the present invention may be used as pharmaceutical compositions for the local treatment of skin lesions, open wounds, inflammation or pain. Additional objects, features and advantages of the disclosure will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the disclosure as described in the written description and claims hereof, as well as the appended drawings. Various features and subcombinations of embodiments of the disclosure may be employed without reference to other features and sub-combinations. BRIEF DESCRIPTION OF THE DRAWINGS Some embodiments of the disclosure will now be described further, by way of example, with reference to the accompanying figures, where like reference numerals or characters indicate corresponding or like components. The description, together with the figures, makes apparent to a person having ordinary skill in the art how some embodiments of the disclosure may be practiced. The figures are for the purpose of illustrative discussion and no attempt is made to show structural details of an embodiment in more detail than is necessary for a fundamental understanding of the disclosure. For the sake of clarity and convenience of presentation, some objects depicted in the figures are not necessarily shown to scale. In the Figures: Figure 1 depicts a simplified schematic diagram of a method for preparing core-shell nano-elements according to embodiments of the present teachings: Figure 2 shows the particle size distribution of core-shell nano-elements prepared according to the present teachings, as measured by dynamic light scattering (DLS) and presented per number; Figure 3 schematically illustrates an uncharged core-shell nano-element in a non-aqueous polar carrier; Figure 4 schematically illustrates a positively charged core-shell nano-element, surrounded by a shell formed of molecules of an active agent; Figure 5A shows a CryoTEM image of a nano-dispersion prepared according to the present teachings, comprising core-shell nano-particles surrounded by a second shell of a carrier-soluble active agent; and Figure 5B shows a CryoTEM image of a nano-dispersion comprising core-shell nanoparticles surrounded by a second shell which have undergone partial coalescence. DETAILED DESCRIPTION The present invention relates to dermatological (e.g., topical) compositions comprising core-shell nano-elements, e.g., nano-particles or nano-droplets, comprising a core composed of a water-insoluble compound capable of stimulating collagen neo-synthesis and / or of inhibiting processes leading to collagen degradation (e.g., a CSSC or a CSSP), and a shell of at least one fatty amine surrounding the core, the fatty-amine(s) non-covalently interacting with the the CSSC, the nano-elements being dispersed as nano-suspension in a polar carrier. Advantageously, the CSSC may have a molecular weight of 0.6 kDa or more and can be, if desired, plasticized by or swelled with a non-volatile liquid, which can also be referred to as a plasticizing or swelling agent. The core-shell nano-elements may by themselves provide for a desired dermatological effect, either as a result of the activity of the CSSC itself, or as a result of its combination with a carrier-insoluble active agent in the core. The nano-elements may alternatively or additionally be used as an anchor or nano-carriers for other cosmetic or pharmaceutical active agents, which are carrier-soluble and can form a second shell on the surface of the nano-elements, the second shell surrounding the first shell of fatty amine(s). When applied to the skin, the nano-elements comprised in the composition can penetrate the skin barrier and provide, inter alia, an anti-wrinkle effect or any such effect restoring skin look, contributed at least in part thanks to the capacity of the CSSC in the cores of the nanoelements to maintain sufficient collagen presence in the skin. If an active agent added to be part of the core and / or to form a second shell is selected to be a cosmetic agent having a cosmetic effect similar to the core-shell, then the initial cosmetic effect that the sole CSSC might have provided can be enhanced (e.g., boosting an anti-wrinkle effect). However, a cosmetic agent of a core (if carrier-insoluble) or of a second shell (if carrier-soluble) may provide for a different cosmetic effect, the core-shell(s) nano-elements combining the effect of the core CSSC and of the cosmetic agent (e.g., of the second shell). As mentioned, the active agent may alternatively serve a more curative goal and can similarly be added as part of the core or as a second shell. The compositions may include any other desired compound, such as any material miscible with the cores or any of the shells of the core-shell(s) nano-elements to enable or increase the dispersibility of the nano-elements in the composition or any other property adapted to increase its stability over time and / or to further enhance or modify the biological activity of the composition. Surfactant(s), activity modifying agent(s) and / or skin permeation enhancer(s) can be present in the polar carrier, if soluble therein. Methods for preparing such dermatological compositions and uses thereof for cosmetical or pharmaceutical effects are also disclosed. Before explaining at least one embodiment in detail, it is to be understood that the disclosure is not necessarily limited in its application to the details of construction and the arrangement of the components and / or methods set forth herein. The disclosure is capable of other embodiments or of being practiced or carried out in various ways. The phraseology and terminology employed herein are for descriptive purpose and should not be regarded as limiting. It is to be understood that both the foregoing general description and the following detailed description, including the materials, methods and examples, are merely exemplary of the disclosure, and are intended to provide an overview or framework to understanding the nature and character of the invention as it is claimed, and are not intended to be necessarily limiting. Biological activity and biodegradability of CSSCs The CSSCs that can be used in the present invention are selected for their ability to promote collagen formation within the skin and / or to prevent its degradation. Without wishing to be bound by any particular theory, it is believed that such compounds, upon their application and penetration into the skin, or their injection therein, can trigger biological signals culminating in neo-synthesis of skin structural proteins. When these compounds are biodegradable, being for instance biodegradable polymers, the CSSCs can be broken down by certain biological mechanisms and cause local inflammation. This process may induce the formation of collagen, for the purpose of healing the inflamed area, this newly synthesized collagen also contributing to the firmness of the skin. In view of their intended use, the CSSCs are typically biocompatible and biodegradable in a physiological environment, such as found following their transdermal delivery; Suitable CSSCs can also be termed bioresorbable or bioabsorbable in the general literature, depending on their in vivo fate and prospective elimination from the body, but for simplicity all such compounds will be generally referred to herein as “biodegradable”. A CSSC is said to be biodegradable if breaking down relatively rapidly after fulfilling its purpose (e.g., by a bacterial decomposition process in the environment or by an in vivo enzymatic or metabolic process) to result in natural by-products. Biodegradable CSSCs are known, and new ones are being developed. Their relative biodegradability in various environments can be assessed by a number of methods, which depending on the conditions of interest can be procedures based on or modified from standards such as ASTM Fl635. Despite its propensity to naturally decompose under suitable physiological conditions, a biodegradable CSSC adapted to the present invention should be stable and durable enough for its intended use during storage and application, which can be particularly challenging if this use involves conditions that would enhance biodegradability. For example, spreading topical compositions containing CSSCs as a thin layer on the skin is expected to form a high surface area, which might increase the exposure of the resulting film to factors (e.g., light, chemicals, or micro-organisms) promoting the degradation of the CSSC before it is able to penetrate the skin and reach its target, hence, the selection of suitable CSSCs for the dermatological (e.g., topical) compositions of the present invention should take these factors into consideration. Insolubility Besides their biodegradability, the CSSCs are preferably substantially non-soluble in the liquid phase of the composition including the polar carrier (e.g., water), in which they are dispersed as nano-elements. As used herein, the solubility of a material (e.g., a CSSC, a fatty amine, a non-volatile liquid, or an active agent) refers to the amount of such component that can be introduced into the liquid (e.g., polar) carrier, while maintaining the clarity' of the liquid medium. The solubilities of specific components of the composition within any particular liquid are typically assessed in the sole polar carrier in absence of any other possible components of the compositions but may be alternatively determined with respect to the final composition of the liquid phase including the carrier. CSSCs (or any other material of interest for the present invention) are deemed insoluble if their solubility in the polar carrier, or in the liquid phase containing it, is 5 wt.% or less, 4 wt.% or less, 3 wt.? / o or less, 2 wt.? / o or less, 1 wt.? / o or less, 0.5 wt.% or less, or 0.1 wt.% or less by weight of the carrier, or of the liquid phase. For illustration, no more than 5 g of a material that is non-soluble in a polar carrier would dissolve in 100 g of the carrier. This substantial insolubility, while typically measured at room temperature, should preferably apply at any temperature at which these ingredients are combined and processed, i.e.. even at relatively elevated temperatures, the solubility of these compounds in the polar carrier should remain within the required ranges. A material satisfying these conditions can be referred to as a “polar-carrier-insoluble” material. Such insolubility of the material is expected to prevent or reduce leaching out into their surrounding media of one or more of the CSSC (or of any other one of the constituents of the cores of the nano-elements). Such leaching out, were the material soluble in the polar carrier, may affect the relative proportions of the constituents of the nano-elements, their size, or any other such parameter that may ultimately adversely affect the efficacy of the composition. Regardless of the composition of the polar liquid phase including the polar carrier in which the core-shell nano-elements are to be dispersed, the CSSC can first be characterized as being water-insoluble (i.e., having a solubility of less than 5 wt.% in water as typically established at room temperature). Molecular weight Advantageously, the present invention allows for the delivery of core-shell nano-elements comprising CSSCs having relatively high molecular weights as compared to compounds that may conventionally sufficiently penetrate the skin barrier to display any efficacy. CSSCs suitable for the present compositions, methods, and uses can have a molecular weight (MW) of 0.6 kDa or more, 0.7 kDa or more, 0.8 kDa or more, 0.9 kDa or more, 1 kDa or more, CSSPs also displaying MW of 2 kDa or more, 5 kDa or more, or 10 kDa or more. Typically, their molecular weight does not exceed 2 kDa if the compound is not a polymer, CSSPs reaching MWs of up to 500 kDa, and being generally of 300 kDa or less, 200 kDa or less, 100 kDa or less, 80 kDa or less, 50 kDa or less, 25 kDa or less, or of 15 kDa or less, hi another embodiment, the molecular weight of the CSSCs is between 0.6 kDa and 500 kDa, between 0.7 kDa and 300 kDa, between 0.8 kDa and 200 kDa, between 1 kDa and 100 kDa, or between 2 kDa and 80 kDa. As used herein, the term “molecular weight” (or “MW”) refers either to the actual molecular weight as can be calculated for a non-polymeric CSSC, which can also be expressed in grams / mole, or to the weight average MW of CSSPs, which may be a blend of polymers each containing a slightly different number of repeating units, weight average MW of polymers being typically expressed in Daltons. The molecular weight of the CSSCs can be provided by their suppliers and can be independently determined by standard methods including for instance gel permeation chromatography, high pressure liquid chromatography (HPLC), size-exclusion chromatography, light scattering or matrix-assisted laser desorption / ionization time-of-flight mass spectroscopy MALDI-TOF MS, some of these methods are described in ASTM D4001 or ISO 16014-3. Such general rules concerning the molecular weight exemplified with respect to the CSSCs can be applied to any other constituent of the composition, whether polymeric or not, and in some embodiments, active agents added to the cores and / or the shells of the nanoelements may also be relatively large molecules having a MW of 0.6 kDa or more, and any other values as specifically recited for the CSSCs. Characterizing temperatures While the vast majority of non-polymeric compounds can be characterized by a melting temperature (Tm) at which they change from a solid phase to a liquid one, polymeric compounds can additionally or alternatively be defined by a glass transition temperature (Tg) if amorphous, pure amorphous polymers lacking a Tm. Pure crystalline polymers can be characterized by their Tm, semi-crystalline polymers often displaying two characterizing temperatures (e.g., Tg and Tm) reflecting the respective proportion of amorphous and crystalline parts in the molecule. Such polymers may also be defined by their softening temperature (Ts) midway the log step to melting. As the glass transition temperature describes the transition of a glass state into a rubbery state, and the softening temperature an intermediate inflection in the thermal analysis of a material, they typically relate to a range of temperatures or one at which the process will first be observed. Therefore, depending on the chemical nature of the CSSC, the temperature that may characterize its thermal behavior can be at least one of a Tm, a Ts and a Tg. Hence, when a CSSC is defined as suitably having at least one of a first and / or second Tm, Ts and Tg within a particular range, the temperature considered is as relevant to the material. Some compounds may be identified by two such characterizing temperatures, in which case performing a method step at a temperature above any of the two temperatures could be above the lowest of the two (which would prolong the step) or the highest of the two (which would accelerate the step). Conversely, performing a method step at a temperature below any of the two temperatures could be below the highest of the two or the lowest of the two. Taking for illustration a semicrystalline polymer that can be characterized by all three temperatures, Tm, Ts, and Tg in order of decreasing values, heating above Tg (i.e., above at least one), might be insufficient to reach Ts or Tm, while heating above Ts (i.e., above at least two), might be insufficient to reach Tm. Only heating above Tm would ensure that the temperature of heating is higher than all three temperatures that may characterize such exemplary polymer. In some embodiments, the CSSCs suitable for the present compositions are characterized by at least one of a melting temperature (Tm), softening temperature (Ts) or glass transition temperature (Tg) being of at least 20°C, at least 30°C, at least 40°C, at least 50°C, or at least 60°C. In other embodiments, at least one of the Tm, Ts and Tg of the CSSCs is at most 300°C, at most 250°C, at most 200°C, at most 180°C, at most 150°C, or at most 120°C. In some embodiments, at least one of the Tm, Ts and Tg of the CSSCs is between 20°C and 300°C, between 20°C and 250°C, between 20°C and 200°C, between 30°C and 180°C, between 40°C and 150°C, or between 50°C and 120°C. Such thermal characteristics of a CSSC can be provided by its manufacturer or independently determined by standard methods, for instance, thermal analysis methods, e.g, Differential Scanning Calorimetry (DSC), such as described in ASTM 3418, ISO 3146, ASTM D1525, ISO 11357-3, or ASTM E1356. The characterizing temperatures (Tm, Ts or Tg) of a CSSC may be referred to as a “first” Tm, Ts or Tg, when relating to the native / unmodified compound, and may be referred to as a “second” Tm, Ts or Tg, when relating to the CSSC as modified, e.g, by its mixing with a non-volatile liquid yielding a plasticized or swelled CSSC. Such general rules concerning a suitable thermal behavior exemplified with respect to the CSSCs can be applied to any other constituent of the cores of the nano-elements which may display or affect a characterizing temperature as herein described. Hence, in some embodiments a constituent of the core (other than the CSSCs) either alone or in combination with the CSSCs and all other materials due to form the core (e.g., active agents, surfactants, etc.) may satisfy the aforesaid ranges. Polymeric and non-polymeric CSSCs In some embodiments, the collagen-synthesis stimulating compounds (CSSCs) used in the present compositions, methods and uses are collagen-synthesis stimulating polymers (CSSPs). As the CSSPs are desirably adapted for biodegradation once delivered into the physiological environment of the skin (e.g., beneath it), such polymers generally contain hydrolysable functional groups. In some embodiments, the CSSCs (or CSSPs) may be non-reactive to build up more complex interactions, being only able to biodegrade, such as PCL. In other embodiments, the CSSCs (or CSSPs) may have reactive moieties enabling interactions with additional molecules, such as PLA. Suitable CSSPs, which can be of natural or synthetic origin, are thermoplastic in nature, their shapes being capable of reversible modifications upon suitable heating and cooling. Appropriate CSSPs can also be plasticized with a suitable non-volatile liquid, such optional treatment of the CSSPs facilitating their nano-sizing to an extent expediting transdermal delivery of the dispersed core-shell nano-elements. Synthetic CSSPs can be selected from aliphatic polyesters, polyhydroxy-alkanoates, poly(alkene dicarboxylates), polycarbonates, aliphatic-aromatic co-polyesters, enantiomers thereof, copolymers thereof and combinations thereof. To the extent that the monomers forming the CSSPs have chiral centers, all enantiomers and stereoisomers are encompassed. For illustration, lactic acid (2-hydroxypropionic acid, LA), exists as two enantiomers, L- and D-lactic acid, so that PLA has stereoisomers, such as poly(L-lactide) (PLLA), poly(D-lactide) (PDLA), and poly(DL-lactide) (PDLLA). A CSSP may therefore be a mixture of isomers of a same molecule or a specific stereoisomer (or a stereo copolymer). In some embodiments, the CSSP is selected from a group comprising: aliphatic polyesters, such as poly-caprolactone (PCL), polylactic acid (PLA), poly(L-lactide) (PLLA), poly(D-lactide) (PDLA), poly(D,L-lactide) (PDLLA), polyglycolic acid (PGA), poly(lactic-co-glycolic acid) (PLGA), and poly(p-dioxanone) (PPDO); polyhydroxy-alkanoates (PHA), including polyhydroxybutyrate (PHB) (such as poly-3-hydroxy-butyrate (P3HB), poly-4-hydroxy-butyrate (P4HB), poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polyhydroxyvalerate (PHV), polyhydroxyhexanoate (PHH), and polyhydroxyoctanoate (PHO); poly(alkene dicarboxylates), such as poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBSA) and poly(ethylene succinate) (PES); polycarbonates, such as poly-(trimethylene carbonate) (PTMC), polypropylene carbonate) (PPC) and poly-[oligo(tetramethylene succinate)-co(tetramethylene carbonate); aliphatic-aromatic copolyesters, such as poly(ethylene terephtalate) (PET) and poly(butylene adipate-co-terephtalate) (PBAT); their isomers, copolymers and combinations thereof. In a particular embodiment, the CSSP is or includes an aliphatic polyester, isomers, copolymers and combinations thereof. In a further particular embodiment, the CSSP is PCL. In another further particular embodiment, the CSSP is PLA. Such polymers may be identified according to their respective characteristic functional groups as detectable by standard methods known to the skilled persons, for instance, by Fourier-transform infrared (FTIR) spectroscopy. Non-polymeric CSSCs suitable for the compositions, methods and uses of the present invention include quinones. In a particular embodiment, the non-polymeric CSSC is coenzyme Q10 (CoQlO). Additionally, a CSSC, can be a blend of different compounds, whether polymeric or not, the properties of the mixture (e.g., a characterizing temperature, a viscosity, etc.) satisfying the ranges set for a suitable individual compound. For instance, a CSSC or CSSP having a Tm, Ts or Tg out of a range previously deemed suitable (e.g., being lower than 20°C or higher than 300°C) may be combined with a CSSC or CSSP having a Tm, Ts or Tg adapted to “correct” the characterizing temperature of the obtained mixture to be suitable for the purpose of the present invention. For illustration, a CSSC can be a blend of polymers or a copolymer including at least one of the aforementioned CSSPs, such copolymers may contribute to the biocompatibility, biodegradability and mechanical and optical properties of the nano-elements. Viscosity CSSCs can alternatively (or additionally) be selected for their viscosity to be adapted to their shearing in the present methods for preparing the dermatological compositions. CSSCs suitable for the present methods, compositions and uses can typically have a viscosity which does not exceed of 1011 millipascal-second (mPas, being equivalent to a centipoise), and which is often of 5xlO10 mPas or less, 10i0 mPas or less, 5xl09 mPa s or less, 109 mPa s or less, 5xl08 mPa s or less, 108 mPa s or less, 5x10’' mPa s or less, 10' mPa s or less, or of 5xl06 mPa s or less, as determined at a temperature of 50°C and a shear rate of 10 sec'h For efficient shearing to take place, the viscosity of the CSSCs should preferably be of 10’' mPa s or less at a temperature of 50°C and a shear rate of 10 sec-1. Such viscosity’ can relate to the native property of the isolated unmodified CSSC, in which case it can be referred to as a “first viscosity”, or it may refer to the viscosity’ of the CSSC as modified by its mixing with materials miscible therewith, in which case it can be referred to as the “second viscosity” of the CSSC. For illustration, the second viscosity can be of a CSSP plasticized with a suitable plasticizing agent (e.g., a non-volatile liquid or a fatty amine). The viscosity of a material (whether modified or not by the presence of others) at any temperature of interest (or in a range thereof) can be determined by routine thermo-rheological analysis, such as described in ASTM D3835 or ASTM D440. The native viscosity of the CSSCs may be lowered by the fatty amine(s) (added to create the shell of the core-shell nano-elements), but a non-volatile liquid can alternatively be added to the CSSC or CSSP regardless of their native viscosity. Such dedicated plasticizing materials are typically used in the present compositions or methods when a reduction in viscosity more significant than optionally achieved by the sole presence of fatty amines is desired (e.g., when the CSSC has a relatively high first viscosity, such as higher than 107 mPa s, at 50°C and a shear rate of 10 sec-1, the first viscosity being however optionally lower). The non-volatile liquid (which may also be referred to as a plasticizing liquid) is contained in the core of the nano-elements, the liquid being typically adsorbed or otherwise retained by the CSSC. Such “plasticizing” or “swelling”, typically results in weight gain and / or a volume gain relative to the CSSC own mass or volume in its native form. Such plasticizing of the CSSC renders the plasticized CSSC softer and more malleable, as demonstrated by its reduced viscosity (i.e., the second viscosity being smaller than the first), facilitating their later nanosizing (together with any other material mixed therewith) to an extent expediting transdermal delivery of the resulting core-shell nano-elements. Advantageously, the reduced viscosity should be adapted to the shearing process (e.g., shearing equipment, shearing temperature, etc.) being elected to nano-size the plasticized CSSC (e.g., a plasticized CSSP) mixed with any other materials miscible in the core and the fatty amine(s) intended to form a first surrounding shell. For instance, the non-volatile liquid and its proportion relative to the CSSC can be selected to lower the viscosity of the CSSC by at least half-a-log, or at least one log, and so on, as might be required. For illustration, if the CSSC has a first viscosity of 108 mPa s, a plasticizing agent and its amount would enable a reduction of half-a-log if the CSSC so plasticized has a second viscosity of 5xl07 mPas, or (if in a higher amount or if alternatively selected to be a more potent agent) would enable a reduction of one log if the CSSC so plasticized has a second viscosity of 107 mPas, as measured at a temperature of 50°C and a shear rate of 10 sec'1. In some embodiments, the second viscosity of a plasticized CSSC is between 102 mPa s and 107 mPa s, between 5xl02 mPa s and 106 mPas, between 5xl02 mPa s and 105 mPa s, between 103 mPa s and 5xl04 mPa s, or between IO-’ mPa s and 104 mPa s, as measured at 50°C and at a shear rate of 10 sec'1. Viscosity can be measured with any suitable rheometer equipped with a spindle adapted to the intended range of viscosities at the appropriate shear rate. Plasticization of CSSCs While mentioned above for their effects on the viscosity of the CSSCs, to the extent reducing it would be desired, the non-volatile liquids that may be incorporated with the CSSC in the cores of the nano-elements may fiilfil additional functions. Plasticizing in particular CSSPs can be visually observed when the swelled polymer is at a temperature below melting. At higher temperatures, the effect of the non-volatile liquid or of the fatty amines can be detected via their plasticizing activity, which includes the ability to lower at least one of the temperatures characterizing the native CSSCs. Decreasing a characterizing temperature of the CSSC, allows accordingly lowering processing temperatures at which the dermatological compositions can be prepared. For illustration, while the CSSC can have a first (native) Tm, Ts or Tg of 200°C or less in absence of a suitable non-volatile liquid, the addition of such plasticizing agents may yield a plasticized CSSC having a second (modified) Tm, Ts or Tg, lower than the first, the second temperature being for instance of 95°C or less. The drop in temperature afforded by the presence of the plasticizing agent need not be as dramatic as illustrated, obviously depending on the value of the first Tm, Ts or Tg of the native CSSC, on the second Tm, Ts or Tg as may be desired to facilitate preparation of the composition and / or later penetration of the core-shell nanoelements, preferably on the boiling temperatures (Tb) of liquids which are to remain present in the composition (but not necessarily if the steps are brief enough and / or the liquids in excess in case some are boiled away), and / or on the concentration of the plasticizing agent with respect to the compound being plasticized. A characterizing temperature of a CSSC may be satisfactorily reduced solely by the fatty amine(s) intended for the formation of the shell. Alternatively, a non-volatile liquid may be additionally combined with the CSSCs in order to further reduce at least of their characterizing temperature. If the mixture of CSSC(s) and plasticizing agent(s) further comprises ingredients (e.g., rheological modifiers, surfactants, preservatives, or any like material which may have a plasticizing effect) that may impact the softening property of the resulting combination due to form the core, or be within, the nano-elements, then additionally and alternatively, the thermal characteristics deemed suitable for the present invention would apply to the entire mixture. Hence, in some embodiments, the plasticized CSSC, or a mixture of components including it, has at least one of a second Tm. Ts and Tg being in a range of 0°C to 290°C, 10°C to 250°C, 20°C to 200°C, 30°C to 180°C, 40°C to 150°C, or 50°C to 120°C. Such thermal behavior and characterizing temperatures can be assessed while preparing the plasticized CSSC or mixtures including the same, or upon completion of the preparation method of the composition. Non-volatile plasticizing liquids While the role that the presence of non-volatile liquids may have in the efficacy of delivering the nano-elements including the CSSC core is not ignored, the selection of such materials is mainly considered with a view of improving the processability of the CSSC, so as to facilitate the preparation and dispersion of the core-shell nano-elements within the polar carrier phase. Particularly suitable non-volatile liquids can both lower the viscosity of the CSSC and lower at least one of its Tm, Ts and Tg, as previously separately discussed. Advantageously, suitable non-volatile liquids improve the processability of the CSSC under conditions suitable for its shearing into nano-particles, the shearing temperature causing initially the formation of nano-droplets. First, as implied by their names, agents adapted to plasticize a CSSC according to the present teachings are liquid at the temperature at which the CSSC is to be processed, namely at least at one of the temperatures of mixing with the CSSC and of shearing. Such liquid agents can also be liquid at room temperature. To ensure that their effect would perdure, the plasticizing liquids are preferably nonvolatile. As used herein, the term “non-volatile”, as can be used with regards to a liquid that may plasticize the CSSC, refers to liquids exhibiting a low vapor pressure, such as less than 40 Pascal (Newton per square meter) at a temperature of about 20°C. Such vapor pressure values are typically provided by the manufacturer of the liquid, but can be independently determined by standard methods, such as described in ASTM D2879, El 194, or E1782 according to the range of the vapor pressure. The low or substantially null volatility of the non-volatile liquids that may be used to plasticize a CSSC, if so desired, should be maintained at the highest temperature at which the plasticized CSSC is processed. The use of such non-volatile liquids allows the CSSCs to remain in their plasticized or swelled state, without the risk of evaporation or elimination of the liquids, even at high temperatures of preparing the dermatological compositions according to the present methods. Suitable non-volatile liquids are also characterized by having a boiling point (Tbi) that is higher than room temperature, higher than body temperature, and higher than an elevated temperature as may be desired for the preparation of the composition, as it is preferred that the liquids selected for plasticizing the CSSCs of the present invention do not substantially evaporate during or after the preparation of the dermatological compositions. That having been said, some boiling away may be tolerated if the mixing step at which the non-volatile liquids plasticize the CSSC is brief enough to ensure a residual presence as desired, and / or if the nonvolatile liquids are added in sufficient excess to compensate for any partial boiling away that may take place. For similar reasons of being desirably maintained with the CSSC to be plasticized therewith, and retained in the nano-elements comprising it, the non-polar liquid should preferably be unable to migrate to the polar carrier phase. Hence, suitable non-volatile liquids are essentially not miscible in such polar carriers (e.g., water), their solubility in the pure polar carrier or in the liquid phase containing it being as previously detailed for the CSSC, namely being of 5 wt.% or less, 4 wt.% or less, 3 wt.% or less, 2 wt.% or less, 1 wt.% or less, of 0.5 wt.% or less, or of 0.1 wt.% or less by weight of the carrier or the phase containing it. Such non-volatile liquids need to be compatible with the CSSC of the composition (i.e., able to plasticize it: e.g., decreasing its Tm, Ts or Tg, and / or decreasing its viscosity). A nonvolatile liquid adapted for a particular CSSC can be selected accordingly by routine experimentation. For instance, given a particular CSSC, various non-volatile liquids can be mixed with it, at one or more relative concentrations, and their effects on the CSSC being plasticized monitored by thermo-rheology (for their ability to decrease viscosity as a function of temperature) and by thermal analysis (e.g., by DSC, for their ability to decrease the Tm. Ts or Tg of the native CSSC). The non-volatile liquids most potent with respect to the particular CSSC can be selected accordingly. Fundamentally, a material or a chemical composition is compatible with another if it does not prevent its activity or does not reduce it to an extent that would significantly affect the intended purpose. Such compatibility niay be from a chemical standpoint, for instance, sharing similar functional chemical groups or each material having respective moieties that may desirably interact with one another. This kind of compatibility can be demonstrated by the combined materials forming a homogeneous mixture, rather than separate into different phases. Materials should also be compatible with the methods used for the preparation of the composition, not being adversely affected by any of the steps the material would be subjected to in the process, nor being volatile (or otherwise eliminated) at the temperature(s) they are incorporated in the compositions. Understandingly, the materials need also be compatible with their intended use, which in the present case may include for illustration being biocompatible, non-irritating, non-immunogenic, and having any such characteristic providing for their regulatory approval at a concentration adapted for efficacious cosmetic or pharmaceutic compositions as herein-disclosed. Non-volatile liquids suitable for the present invention can be selected from: monofunctional or polyfunctional aliphatic esters (such as ethyl acetate, butyl lactate, dimethyl glutarate, dimethyl maleate, dimethyl methyl glutarate, ethyl lactate and lactic acid isoamyl ester); fatty esters (such as 2-ethylhexyl lactate, acetyl tributyl citrate, acetyl triethyl citrate, acetyl triethyl hexyl citrate, allyl hexanoate, benzyl benzoate, butyl butyryl lactate, C12-C15 allcyl benzoate, a mixture of caprylyl caprate and caprylyl caprylate, decyl oleate, dibutyl adipate, dicaprylyl carbonate, dibutyl maleate, dibutyl sebacate, diethyl succinate, ethyl oleate, glyceryl monooleate, glyceryl monocaprate, glyceryl tricaprylate, glyceryl trioctanoate, isopropyl myristate, isopropyl palmitate, L-menthyl lactate, lauryl lactate, n-pentyl benzoate, PEG-6 caprylic / capric glycerides, propylene glycol monolaurate, propylene glycol monocaprylate, triacetin, triethyl citrate, triethyl o-acetylcitrate, tris(2-ethylhexyl) o-acetyl-citrate, tributyl o-acetylcitrate and tributyl citrate); cyclic organic esters (such as decanoic lactone, gamma decalactone, menthalactone and undecanoic lactone); fatty acids (such as caprylic acid, cyclohexane carboxylic acid, isostearic acid, lauric acid, linoleic acid, linolenic acid, myristic acid, oleic acid, palmitic acid and stearic acid); terpenes (such as citronellol, eugenol, farnesol, hinokitiol, D-limonene, linalool, menthol, menthone, neridol, terpineol and thymol); aromatic alcohols (such as benzyl alcohol); aromatic ethers (such as methoxy benzene); aldehydes (such as cinnamaldehyde); and combinations thereof. In a particular embodiment, the non-volatile liquid that may be used to plasticize a CSSC as herein-disclosed is a polyfunctional aliphatic ester (PFAE), being a diester derivative of common dicarboxylic acids: namely adipic (Ce), azelaic (C9) and sebacic (Cio) acids, the alcohol portion of the diesters generally falling in the C3-C20 carbon number range, including linear and branched, even and odd numbered alcohols. Dibutyl adipate {e.g., commercially available as Cetiol® B) is an example of a PFAE suitable to plasticize a CSSC, in particular a CSSP, according to one embodiment. Another suitable non-volatile liquid is triethyl O-acetylcitrate (e.g., commercially available as Citrofol® All). Fatty amines Fatty amines suitable for forming the shell (or the first shell) surrounding the CSSC made core of the nano-elements are primary, secondary or tertiary amines, having a hydrophobic alkyl chain, the alkyl being a Cs-20 straight, branched, or cyclic, saturated or unsaturated alkyl chain. Combinations of such fatty amines may also be used. Alkyl chains of such length create a fatty “tail”, attached to the amine “head”. Hence, the amine molecule contains a hydrophobic part ( / . e., the fatty tail) and a hydrophilic part (z.e., the amine head). The arrangement of the amine molecules within the core-shell nano-elements is to be discussed further below. The hydrophobic tail renders the fatty' amine water-insoluble, i.e., having a solubility of 5 wt.% or less, 4 wt.% or less, 3 wt.% or less, 2 wt.% or less,l wt.% or less, 0.5 wt.% or less, or 0.1 wt.% or less by weight of the polar carrier (similarly to the CSSCs). Primary amines, suitable for the purpose of the present teachings include oleyl amine. Primary amines are advantageous with respect to the charge they may provide to the shell, as compared to secondary' and tertiary amines. Without wishing to be bound by any particular theory, it is believed that secondary and tertiary amines are advantageous when transdermal delivery of nano-elements having only a single shell of fatty amines, as they have a lower tendency to form reactive nitrogen hydrides (e.g., NHy) which might cause skin irritation. Such secondary and tertiary' amines can be selected from: N,N-Bis-(2-hydroxyethyl)Ci2-Ci8- alkylamine octylamine, N,N-dimethyl-dodecylamine and cetrimonium chloride. In particular embodiment, the fatty amine is N,N-Bis-(2-hydroxyethyl)Ci2-Cis-alkylamine. In another particular embodiment, the fatty amine is oleyl amine. As previously described, some of the fatty amines may act as plasticizers, their addition decreasing the viscosity of the CSSC used therewith, such an effect is described in Example 1 below with respect to fatty amines. Optional water-insoluble active agents could similarly possess this ability. Alternatively, or additionally, the fatty amines may also serve as surfactants, suitable to stabilize the core-shell nano-elements within the polar carrier. At high temperatures, a fatty amine may be prone to degradation, resulting in amine loss (due to amidation by oxidation of the amine). Analysis of such degradation can be performed by placing the fatty amine at a tested temperature for a sufficient amount of time, e.g. 24 hours, and then measuring the amine value by routine analysis using standard methods, such as described for instance in ASTM D 2074-07. By way of non-limiting example, the amine value can be assessed by titration of the fatty amine (having been subjected to the tested temperature) with hydrochloric acid, the amine value corresponding to the volume of 0. IN HC1 in milliliters needed to neutralize 10g of product. The obtained result is then compared to the amine value of the same fatty amine in natural, non-heated form, which is provided by the manufacturer, or can be independently measured as described above. Any reduction in the value of the amine number of the heated fatty amines may suggest the degradation of the amines at the tested temperature (such temperature being referred to as the “degradation point” of the fatty amine). The temperatures used in preparing the core-shell nano-elements of the present invention should accordingly be below the degradation point, so as to substantially maintain the amine groups in a reduced / non-oxidized state. Polar medium The liquid medium forming the continuous phase in which nano-elements including the core made of CSSC are dispersed is polar. In some embodiments, the liquid phase consists essentially of a polar carrier, whereas in other cases additional components can be present within the polar carrier. Such additional components can be, for illustration, surfactants, carriersoluble active agents, or skin permeation enhancers, as herein-detailed, or any other additives conventionally present in dermatological compositions. A polar carrier suitable for the present invention can be selected from a group comprising water, glycols (e.g., ethylene glycol, propylene glycol, dipropylene glycol, and 1,2-butanediol 1,3-butanediol, 1,4-butanediol, 2-ethyl-1,3-hexanediol and 2-methyl-2-propyl-1,3-propanediol), glycerols including glycerol, precursors and derivatives thereof (e.g., acrolein, dihydroxyacetone, glyceric acid, tartronic acid, epichlorohydrin, glycerol tertiary butyl ether, polyglycerol, glycerol ester and glycerol carbonate) and combinations thereof. A polar medium may be formed of one or more suitable polar carriers, the resulting liquid being often referred as an aqueous solution (or an aqueous phase) when water is the preponderant polar carrier. In some cases, a liquid deemed not sufficiently polar by itself (such as a fatty alcohol) can be present in the liquid phase in addition to the polar carrier(s), provided that the liquid insufficiently polar to form the entire liquid polar phase is a) soluble in the main polar carrier (e.g., having a water-solubility of 5 wt.% or more) so as to form a unique liquid phase therewith; and b) the overall polarity of the liquid phase is maintained. The polarity index of the resulting liquid phase may be of 3 or more, 4 or more, or 5 or more, water having for reference a polarity index of 9-10. As the polarity index of a solvent refers to its relative ability to dissolve in test solutes, a liquid may additionally or alternatively be classified as polar or non-polar in view of its dielectric constant (¾). Liquids having a dielectric constant of less than 15 are generally considered non-polar, while liquids having a higher dielectric constant are considered polar; the relative polarity of a liquid increasing with the value of the dielectric constant. Preferably, the polar carrier suitable for the present compositions has a dielectric constant of 20 or more, 30 or more, 40 or more, 50 or more, or 60 or more, as established at room temperature. For illustration, the dielectric constant of propylene glycol is 32, the dielectric constant of glycerol is 46, and the dielectric constant of water is 80. While for simplicity, this guidance is provided for a neat polar carrier, this in fact should preferably apply to the entire polar liquid phase prepared therefrom (e.g., including additional polar-soluble materials and / or consisting of a mixture of liquid carriers). Noticeably, a liquid polar phase can be constituted of a mix of formally polar solvents (e.g., having >15) with formally non-polar ones (e.g., having Er< 15), as long as their respective volume allows for the entire liquid phase to be polar (e.g., having e? >15). The dielectric constant of a liquid is typically provided by the manufacturer but can be independently determined by any suitable method, such as described in ASTM-D924. As discussed, the composition of the polar liquid phase should be such that the core-shell nano-elements including the CSSCs in their cores and the fatty amines in their first shells can remain essentially non-soluble and stably dispersed therein, with no significant leaching of the contents of the nano-elements into their surrounding medium. As the polar medium may comprise additional liquids and / or materials dissolved therein, the polar carrier can constitute at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, or at least 90 wt.%, by weight of the liquid phase. In some embodiments, the polar carrier comprises water (e.g., 45 wt.% water, 45 wt.% propylene glycol, and 10% of a fatty alcohol), consists of water (e.g., including between 51 wt.% and 80 wt.% of water), consists essentially of water (e.g., including between 81 wt.% and 99 wt.% of water), or is water. Surfactants Some CSSCs may remain nano-dispersed in the dermatological composition in view of their inherent chemical properties, the nano-elements for instance having a charge sufficient to ensure repulsion of the particles, consequently ensuring their stable dispersion. Other CSSCs may alternatively or additionally remain nano-dispersed in view of being plasticized with a nonvolatile-liquid additionally serving as a surfactant to a sufficient extent. The fatty amines may also serve as surfactants, aiding in dispersing the nano-elements within the polar carrier. However, in some embodiments, the composition may further comprise at least one (dedicated) surfactant, for the core-shell nano-elements to remain dispersed (hence also in their intended size range). Surfactants suitable for the purpose of the present invention lower the surface tension between the core-shell nano-elements containing the CSSCs in their cores and the fatty amines in their first shells and the environment in which they are immersed. Depending on then chemical formula (and on the CSSC and polar carrier being considered), the surfactants can be miscible with the CSSCs or with the polar carrier wherein the nano-suspension is formed. Surfactants suitable for the present compositions and methods are generally amphiphilic, containing a polar or hydrophilic part and a non-polar or hydrophobic part. Such surfactants may be characterized by Hydrophilic-Lipophilic Balance (HLB) values within the range of 1 to 35, wherein the HLB values, which generally imply compatibility with water systems, are typically provided on Griffin scale. Suitable surfactants for the purpose of the present invention can be anionic, cationic, amphoteric or non-ionic surfactants. When it is desired that the core-shell nano-elements of the present invention be positively charged in aqueous environments, for instance to promote the attachment of additional shells made of materials (e.g, active agents) having an opposite charge in the same medium, cationic surfactants can be suitable for the purpose of maintaining, and even augmenting the positive charge of the nano-elements. Non-ionic or amphoteric surfactants, and even more so anionic surfactants, are more likely to reduce a positive charge of core-shell nano-elements, therefore their concentration should be adapted so that the overall charge remains sufficiently positive, when desired, hi some embodiments, when a non-ionic, amphoteric, or anionic surfactants are used, they are added at a weight ratio of at most 1:1 with respect to the weight of the fatty amine(s). Cationic surfactants can be selected from the group including: quaternary ammonium compounds (e.g, benzalkonium chloride, stearalkonium chloride, centrimonium chloride, and trimethyl ammonium methyl sulfates). Non-ionic surfactants can be selected from the group including: fatty alcohols (e.g., cetearyl alcohol); ethoxylated fatty alcohols (e.g., Cs-Cis alcohol polyglycol, polyoxyl 6 stearate and polyoxyl 32 stearate): poly (ethylene glycol) block copolymers (e.g.; poloxamer); ethylene oxide (EO) / propylene oxide (PO) copolymers; alkylphenol ethoxylates (e.g., octylphenol polyglycol ether and nonylphenol polyglycol ether); alkyl glucosides and polyglucosides (e.g., lauryl glucoside); fatty alkanolamides (e.g., lauramide diethanolamine and cocamide diethanolamine); ethoxylated alkanolamides; ethoxylated fatty acids; sorbitan derivatives (e.g., polysorbates, sorbitan laurate, sorbitol, 1,4-sorbitan, iso-sorbide and 1,4-sorbitan triester, PEG-80); alkyl carbohydrate esters (e.g., saccharose fatty acid monoester); amine oxides; ceteareths; oleths; alkyl amines; fatty acid esters (e.g., ascorbyl palmitate, ethylene glycol stearate, polyglyceryl-6 esters, polyglyceryl-6 pentaoleate, polyglyceryl-10 pentaoleate and polyglyceryl-10 pentaisostearate); polyoxylglycerides (e.g., oleoyl polyoxyl-6 glycerides); natural oil derivatives; ester carboxylate (e.g., D-a-tocopherol polyethylene glycol succinate (vitamin E TPGS)); and urea. Amphoteric surfactants can be selected from the group including: betaines (e.g., cocamidopropyl betaine); alkylamphopropionates (e.g, cocoamphopropionate); alkyliminopropionates (e.g., sodium lauraminopropionate); and alkylamphoacetates (e.g., cocoampho-carboxyglycinate. Anionic surfactants can be selected from the group including: alkyl sulfates (e.g, sodium lauryl sulfate, ammonium lauryl sulfate and ammonium laureth sulfate); sulfosuccinates (e.g, disodium lauryl sulfosuccinate, disodium laureth sulfosuccinate, sodium dioctyl sulfosuccinate and their mixtures with sulfonic acids and lauramidopropyl betaine; alkyl benzene sulfonates (e.g., sodium tosylate, cumene sulfonate, toluene sulfonic acid, xylene sulfonic acid, cumene sulfonic acid and salts (e.g., sodium, potassium, calcium, ammonium) thereof); acyl methyl taurates (e.g., sodium methyl lauroyl taurate and sodium methyl cocoyl taurate); acyl sarcocinates (e.g., sodium lauroyl sarcosinate, sodium cocoyl sarcosinate and sodium myristoyl sarcosinate); isethionates (e.g., sodium butyl isethionate, sodium capryloyl isethionate and sodium lauroyl isethionate); propyl peptide condensates; monoglyceride sulfates; ether sulfonates and fatty acid salts (e.g., sodium stearoyl lactylate). These surfactants may be categorized into emulsifiers and hydrotropes, according to their mechanism of action. Emulsifiers readily form micelles (thus being characterized by a critical micelle concentration (CMC) value) and are believed to increase the dispersibility of the CSSC (or plasticized CSSC) when later combined with a polar carrier to yield a nano-suspension. As a rule, emulsifiers typically relate to surfactants ensuring the dispersion of one liquid into another, the liquids having opposite polarity, whereas dispersants relate to surfactants ensuring the dispersion of a solid into a liquid. As the present method may provide for nano-emulsions and nano-dispersions, surfactants referred to as emulsifiers at a step the nano-suspension is an emulsion, may in fact become dispersants, to the extent that an initial nano-emulsion later yields a nano-dispersion at a lower temperature. Hence, as used herein, the term “emulsifier(s)” also includes surfactants otherwise known as dispersants. Emulsifiers that are lipophilic in nature, i.e., include a relatively large hydrophobic part, are more suitable to be combined with the CSSC (and any other material not miscible in the polar carrier, e.g., a fatty amine or a non-volatile liquid), and may therefore be referred to as polar-carrier-insoluble emulsifiers (or surfactants, in general). Hence, such relatively hydrophobic emulsifiers are expected to be within the core of the nano-elements of the composition. These relatively hydrophobic emulsifiers generally have HLB values of 9 or less, 8 or less, 7 or less, or 6 or less, on Griffin scale. The behavior of such surfactants may be considered similar to that of the fatty amines since the hydrophobic part of the surfactants turns toward the cores and is embedded therein, and their hydrophilic part turns towards the shell, and may even be part of the shell including the amine heads. Emulsifiers that are more hydrophilic in nature have a relatively large hydrophilic part and would be more compatible with the polar phase of the composition, and may therefore be referred to as polar-carrier-soluble emulsifiers (or surfactants, in general). Such relatively hydrophilic emulsifiers generally have HLB values of 11 or more, 13 or more, 15 or more, 17 or more, or 20 or more. Emulsifiers having HLB values within the range of 9 and 11 are considered “intermediate”, the hydrophobic and hydrophilic parts of such emulsifiers being fairly well-balanced. Such intermediate emulsifiers can be added in the present methods either to the CSSC or the polar carrier and may accordingly be found in the nano-elements or in their medium, the ability of a portion of such surfactants to migrate between the two phases being also envisioned. In a particular embodiment, the surfactant serving as an emulsifier is selected from: vitamin E TPGS, poly (ethylene glycol) block copolymer, a mixture of polyoxyl 6 stearate type I, ethylene glycol stearates and polyoxyl 32 stearate type I (such as commercially available as Tefose® 63 from Gattefosse, France), mixtures comprising olive oil-derived extracts (such as commercially available under the brand Olivatis® from Medolla Iberia, Spain), ascorbyl palmitate, polyglyceryl-10 pentaoleate, poly glyceryl-10 pentaisostearate, oleoyl polyoxyl-6 glycerides (such as commercially available as Labrafil® M 1944 CS from Gattefosse, France), disodium laureth sulfosuccinate, disodium lauryl sulfosuccinate, a mixture of disodium lauryl sulfosuccinate, sodium C14-C16 olefin sulfonate and lauramidopropyl betaine (such as commercially available as Cola®Det EQ-154 from Colonial Chemical, USA) and a mixture of olive oil and glutamic acid (such as commercially available as Olivoil® glutamate from Kalichem, Italy). While surfactants acting as emulsifiers are generally sufficient to stabilize nano-elements of the present compositions, the Inventors have found that when CSSCs are present at a relatively high concentration, as enabled by the invention, the addition of another type surfactants, namely hydrotropes, assisted in achieving a satisfactory stability. Hydrotropes are also amphiphilic molecules, but contrary to emulsifiers, they contain a relatively shorter lipophilic chain. As the lipophilic portion of the hydr otropes is generally too short to allow micelle formation, the hydrotropes alternatively solubilize hydrophobic compounds in the polar carrier and permit co-emulsification, together with the emulsifier. Generally, hydrotropes are miscible mainly in the polar carrier phase (e.g., aqueous phase) of the nano-suspension, and are characterized by having HLB values of 10 or more, 12 or more, 15 or more or 18 or more. Suitable hydrotropes can be selected from the group including: sodium di octyl sulfosuccinate, urea, sodium tosylate, adenosine triphosphate, cumene sulfonate, toluene sulfonic acid, xylene sulfonic acid, cumene sulfonic acid and salts thereof. In a particular embodiment, the hydrotrope is selected from: sodium dioctyl sulfosuccinate, urea and a salt of xylene sulfonic acid, such as ammonium xylenesulfonate. Active agents While the present dermatological compositions can be biologically active as a result of the presence of the CSSC by itself, their uses can be enhanced and / or modified by inclusion of active agents having similar functions, so as to enhance efficacy, and / or different functions, so as to broaden the scope of efficacy. In such case, the core-shell nano-elements can be considered as nano-carriers for other active agents. In some embodiments, the dermatological composition further comprises one or more polar-carrier-insoluble active agent(s). Such carrier-insoluble active agent(s) are generally comprised within the cores of the core-shell nano-elements, as they are miscible with the components included therein, i.e., CSSCs, and optional non-volatile liquid, as well as with the hydrophobic tails of the fatty amines, embedded within the cores. The constituents of the cores are miscible one with the other when forming a unique phase. In some embodiments, and similar to the CSSC and non-volatile liquid described above, the optional carrier-insoluble active agent should have a solubility of 5 wt.% or less, 4 wt.% or less, 3 wt.% or less, 2 wt.% or less, 1 wt.% or less, 0.5 wt.% or less, or 0.1 wt.% or less by weight of the polar carrier or the liquid phase including it. The carrier-insoluble active agent, incorporated into the nano-elements, may include benzoyl peroxide, erythromycin, macrolides, retinol, salicylic acid, tetracyclines, tretinoin, vitamin A, vitamin D, and vitamin K. In particular embodiments, the carrier-insoluble active agent is retinol. In some embodiments, the dermatological composition further comprises one or more polar-carrier-soluble active agent(s), which would surround the first shell of the fatty amines, forming a second shell. The second shell may be composed of more than one layer of a carriersoluble active agent(s). As already mentioned, the formation of such second shells can be favored by non-covalent (e.g., electrostatic) interactions between the fatty amines of the first shell and the carrier soluble agents, or by covalent binding between the two. Excess of polar carrier-soluble active agent(s) may additionally be found in dissolved form within the polar carrier. Exemplary active agents that are carrier-soluble can be selected from: azelaic acid, biotin, clindamycin, collagen, elastin, folacin, hyaluronic acid (HA), niacin, pantothenic acid riboflavin, thiamin, vitamin B12, vitamin B6 and vitamin C. In particular embodiments, the carrier-soluble cosmetically active agent is HA. It is known that high molecular weight (HMW) carrier-soluble active agents are unable to transfer through the skin when formulated into topical compositions. Such HMW compounds, when dissolved in an aqueous environment, tend to unfold and form expanded structures, which are less likely to pass through any of the pathways existing across the skin. HMW molecules are therefore expected to remain on the outer surface of the skin, when not totally washed away therefrom. In contrast, the objective of the nano-elements of the present invention is to penetrate into the skin, where they can act as collagen-synthesis stimulants. The core-shell structure of the nano-elements allows HMW active agents to align as an outer (second) shell and be thus transported into the skin in a compacted manner. The core-multi-shells architecture is therefore expected to enable transdermal delivery of active agents even having a HMW, so that they may display their activity within the target site. In some embodiments, the carrier-soluble active agent that may be combined with the core-shell nanoelements of the invention is hyaluronic acid and both HA of low molecular weight (LMW), i.e.. having a MW of less than 600 kDa, and HA of high molecular weight (HMW), i.e., having a MW of more than 600 kDa can be used. In some embodiments, the HA is a LMW HA having a MW of 500 kDa or less, 400 kDa or less, 300 kDa or less, 200 kDa or less, or 100 kDa or less. In particular embodiments, the LMW HA has a molecular weight not exceeding 50 kDa, not exceeding 25 kDa, or not exceeding 10 kDa. In some embodiments, the dermatological composition may comprise both a carrier-insoluble active agent and a carrier-soluble active agent. Plant extracts, serving as active agents, may also be added to the compositions, and can either be carrier-insoluble or carrier-soluble. As used herein, the term “plant extracts” refers both to natural fractions isolated from any relevant part of any suitable plant (e.g., flowers, fruits, herbs, leaves, peels, roots, seeds, stems, etc.) and to the synthetic version of the active agents of the natural extracts. Plants, the natural extracts of which are traditionally used for cosmetic or therapeutic effects when applied to the skin, are known to the skilled persons and too numerous to be comprehensively listed. By way of example, a plant extract containing an active agent suitable for the present invention can be isolated from bergamot, broccoli, coffee, com, curcumin, fennel, garden angelica, ginseng, grapefruit, honeybush, Japanese red pine, kale, orange, paprika, passion fruit, raspberry, rooibos, soybean, spinach, tea and tomatoes. Such plant extracts are known to have inter alia anti-acne, anti-oxidant, anti-inflammatory, and / or anti-aging activity. The carrier-insoluble and / or carrier-soluble active agents optionally added to the present dermatological compositions may have a cosmetic function, for instance, have a dermal filling effect, or may, by themselves, be capable of enhancing collagen synthesis (and / or reducing its degradation). Considering the collagen synthesis stimulating ability of the CSSCs or CSSPs within the core of the nano-elements on their own, adding such active agents, which may serve a similar purpose, can result in a combined activity providing for an even higher collagen formation within the skin. Regardless of the exact cosmetic contribution of the active agents, the resulting dermatological compositions may be regarded as “cosmetically active”. Alternatively, the active agents (carrier-soluble or -insoluble) may serve pharmaceutical purposes, rendering the compositions “pharmaceutically active”. Hence, the core-shell nano-elements, in addition to their collagen-synthesis abilities, may be used as nano-carriers for cosmetic or pharmaceutical agents. Skin-penetration enhancers While the polar carriers may suffice to enable enough delivery of the CSSC nanoelements through the skin, and some surfactants (if present) can promote it, in some embodiments, the topical composition further comprises a skin-penetration enhancer. Suitable skin-penetration enhancers can be selected from the group comprising: C1-C22 alcohols (such as short chains alcohols: ethanol, isopropyl alcohol, and hexanol, and fatty alcohols: octanol, decanol, lauryl alcohol, myristyl alcohol, oleyl alcohol and octyl dodecanol); amides such as 1 -dodecylazacycloheptan-2-one (also known as laurocapram and commercialized as Azone®) and its analogues, N-alkyl-azacycloheptan-2-ones, where the alkyd has the general formula CxHsx+i, X being an integer selected from 1, 3-10, and 14, azacycloheptan-2-ones N-substituted by branched and / or unsaturated chains, N-acylazepan-2-ones, substituted 2-(2-oxoazepan-l-yl) alkanoic acid and its esters, N-alkyl-azacycloheptan-2-thiones, N-alkyl-azacycloheptenones, 4-alkyl-l,4-oxazepan-5,7-dione; cyclic amines with alkyl having the general formula CxHix i, X being an integer selected from 10-12, 14, 16, and 18; long-chain N-acylazepanes, dehydrogenated azacycloheptane derivatives, six-membered ring analogues such as: azacycloheptadienes, N-substituted piperidin-2-ones, derivatives of sixmembered ring analogues of Azone®, esters of 2-(2-oxopiperidin-l-yl)acetic acid, N-substituted derivatives of 6-oxopiperidine-2-carboxylic acid, N-l-(2-alkylsulfanylethyl)-piperidine-3-carboxylic acids, (thio)morpholines, morpholine-dione derivatives, long-chain N-acylmorpholines, long-chain N-morpholinylalkenones, five-membered ring analogues: long-chain N-acylmorpholines and morpholinoethanol derivatives, 1-piperazin-1-yl-alkan-l-ones and l-(4-methylpiperazin-l-yl)-alkan-l-ones; aromatic esters (such as octyl salicylate and 2-ethylhexyl 4-(dimethylamino)benzoate); ether alcohols (such as 2-(2-ethoxy-ethoxy)ethanol); glycols; pyrrolidones (such as 2-pyrrolidone and N-methyl-2-pyrrolidone); and sulphoxides (such as dimethyl sulphoxide (DMSO) and decylmethyl sulphoxide). It can be noted that some materials above defined as skin penetration enhancers may additionally serve as part of the liquid phase, provided that their combination with the main polar carriers does not affect the overall polarity of the liquid and the lack of solubility of the nano-elements therein. Compositions Having reviewed the various components that may be used in the present dermatological compositions, suitable concentrations or respective proportions shall be provided below. It is to be noted that some of the components according to the present teachings can serve in more than one role. For instance, fatty amines may have plasticizing and / or dispersing abilities and some non-volatile liquids, such as aliphatic esters (e.g., ethyl acetate); fatty acids (e.g., lauric acid, linoleic acid, linolenic acid, myristic acid, oleic acid, palmitic acid, stearic acid and isostearic acid); fatty acid esters (e.g., ethyl oleate, glyceryl monooleate, glyceryl monocaprate, glyceryl tricaprylate, isopropyl myristate, isopropyl palmitate, propylene glycol monolaurate and propylene glycol monocaprylate); and terpenes (e.g., eugenol, D-limonene, menthol, menthone, famesol and neridol); may also have skin penetration enhancing properties. In yet another example, some polar carriers, such as water and certain glycols and glycerols, may also assist skin-penetration, or even serve as surfactants. Thus, when referring, for instance, to the concentration of skin-penetration enhancers in the composition, the information refers only to dedicated compounds intentionally added to serve this role, excluding compounds having a different primary role in the composition. In some embodiments, the concentration of the CSSC (or combination thereof) in the nano-elements is within the range of 1 wt.% to 99 wt.%, 1 wt.% to 90 wt.%, 5 wt.% to 80 wt.%, 10 wt.% to 50 wt.%, or 15 wt.% to 40 wt.% by total weight of the nano-elements. In some embodiments, the concentration of the CSSC(s) in the dermatological composition is within the range of 0.1 wt.% to 30 wt.% by total weight of the composition, preferably in the range of 0.5 wt.% to 25 wt.%, 1 wt.% to 20 wt.%, or of 1.5 wt.% to 15 wt.%. In other embodiments, the CSSC(s) concentration is at least 0.1 wt.%, at least 0.5 wt.%, at least 1 wt.%, or at least 1.5 wt.%, by total weight of the composition. In other embodiments, the concentration of the CSSC(s) is at most 30 wt.%, at most 25 wt.%, at most 20 wt.%, or at most 15 wt.% by total weight of the composition. In some embodiments, the concentration of the fatty amine (or combination thereof) in the nano-elements is within the range of 1 wt.% to 99 wt.%, 1 wt.% to 90 wt.%, 5 wt.% to 80 wt.%, 10 wt.% to 50 wt.%, or 15 wt.% to 40 wt.% by total weight of the nano-elements. In some embodiments, the concentration of the fatty amine(s) in the dermatological composition is within the range of 0.1 wt.% to 30 wt.% by total weight of the composition, preferably in the range of 0.5 wt.% to 25 wt.%, 1 wt.% to 20 wt.%, or of 1.5 wt.% to 15 wt.%. In other embodiments, the fatty amine(s) concentration is at least 0.1 wt.%, at least 0.5 wt.%, at least 1 wt.%, or at least 1.5 wt.%, by total weight of the composition. In other embodiments, the concentration of the fatty amine(s) is at most 30 wt.%, at most 25 wt.%, at most 20 wt.%, or at most 15 wrt.% by total wreight of the composition. In some embodiments, the concentration of the non-volatile liquid(s), if present in the nano-elements, is within the range of 1 wt.% to 98 wt.% by total weight of the nano-elements, preferably in the range of 5 wt.% to 90 wt.%, 10 wt.% to 80 wt.%, or 20 wt.% to 70 wt.%. In some embodiments, the concentration of the non-volatile liquid(s) is at least 1 wt.%, at least 5 wt.%, at least 10 wt.%, or at least 20 wt.% by weight of the nano-elements. In other embodiments, the concentration of the non-volatile liquid(s) is at most at most 98 wt.%, at most 90 wt.%, at most 80 wt.%, or at most 70 wt.% by weight of the nano-elements. In some embodiments, the concentration of the non-volatile liquid(s), if present in the dermatological composition, is within the range of 1 wt.% to 30 wt.% by total weight of the composition, preferably in the range of 2 wt.% to 30 wt.%, 3 wt.% to 25 wt.%, or of 5 wt.% to 20 wt.%. In some embodiments, the concentration of the non-volatile liquid(s) is at least 1 wt.%, at least 2 wt.%, at least 3 wt.%, or at least 5 wt.% by weight of the dermatological composition. In other embodiments, the concentration of the non-volatile liquid(s) is at most at most 30 wt.%, or at most 25 wt.%, at most 20 wt.% by weight of the dermatological composition. When a non-volatile liquid(s) (or a combination thereof) is added, it is at a concentration of up to 400 wt.% by weight of CSSC, preferably within a range of 5 wt.% to 350 wt.%, 10 wt.? / o to 200 wt.%, or 25 wt.% to 150 wt.%.In some embodiments, the concentration of the surfactant(s), if present in the nano-elements, is within the range of 1 wt.% to 50 wt.%, within the range of 5 wt.% to 50 wt.%, within the range of 10 wt.% to 50 wt.%, within the range of 15 wt.% to 45 wt.%, or within the range of 20 wt.% to 40 wt.% by total weight of the nano-elements. These concentrations refer to dedicated surfactant intentionally added for this purpose and do not include the presence of any other material capable of also serving as surfactants, such as some fatty amine(s). In some embodiments, the combined concentration of the dedicated surfactants (including, for instance, the emulsifiers and / or hydrotropes), if present in the dermatological composition, is within the range of 0.1 wt.% to 60 wt.%, within the range of 0.5 wt.% to 50 wt.%, within the range of 1 wt.% to 40 wt.%, or within the range of 1 wt.% to 30 wt.% by total weight of the composition. In some embodiments, the combined concentration of the surfactants is at least 0.1 wt.%, at least 0.5 wt.%, or at least 1 wt.% by total weight of the composition. In other embodiments, the combined concentration of the surfactants is at most 60 wt.%, at most 50 wt.%, at most 40 wt.%, or at most 30 wt.% by total weight of the composition. In some embodiments, the polar carrier is present in the dermatological composition within the range of 10 wt.% to 99.8 wt.%, 20 wt.% to 99 wt.%, 30 wt.% to 90 wt.%, or 40 wt.% to 85 wt.% by total weight of the composition. In some embodiments, the carrier-insoluble active agent, if present in the nano-elements, is added to the CSSC at a concentration of up to 50 wt.% by weight of CSSC, preferably within the range of 0.5 wt.% to 35 wt.%, within the range of 1 wt.% to 20 wt.%, within the range of 2.5 wt.% to 15 wt.%, or within the range of 0.5 wt.% to 10 wt. In some embodiments, the carrier-soluble active agent, if present, is added to the nanosuspension at a concentration of up to 200 wt.% by weight of CSSC, preferably within the range of 0.1 wt.% to 170 wt.%, within the range of 1 wt.% to 150 wt.%, within the range of 5 wt.% to 100 wt.%, within the range of 5 wt.% to 50 wt.%, within the range of 5 wt.% to 40 wt.%, or within the range of 10 wt.%, up to 20 wt.%. In some embodiments, the concentration of any one of the active agents, either carrier-soluble or carrier-insoluble, or of all of them if more than one, in the dermatological composition, is within the range of 0.01 wt.% to 15 wt.% by total weight of the composition, preferably in the range of 0.05 wt.% to 15 wt.%, 0.1 wt.% to 13 wt.%, 0.5 wt.% to 11 wt.%, or 0.5 wt.% to 10 wt.%, . In some embodiments, the concentration of any one of the active agents is at least 0.01 wt.%, at least 0.05 wt.%, at least 0.1 wt.%, or at least 0.5 wt.% by total weight of the composition. In other embodiments, the concentration of all the active agents or the sole one is at most 15 wt.%, at most 13 wt.%, at most 11 wt.%, or at most 10 wt.% by total weight of the composition. In some embodiments, the concentration of the skin-penetration enhancer(s), if present in the dermatological composition, is within the range of 0.01 wt.% to 30 wt.%, 0.1 wt.% to 25 wt.%, 1 wt.% to 20 wt.%, 3 wt.% to 15 wt.%, or 5 wt.% to 15 wt.% by total weight of the composition. Preferably, the aforesaid ingredients are approved for cosmetic use at the envisioned concentrations. For instance, they do not irritate the skin, nor lead to allergic reactions, or any other acute or chronic adverse effect. Moreover, all ingredients need be compatible one with another, such compatibility being as described above. As readily understood, this principle of compatibility, which can be affected not only by the chemical identity of the materials, but by their relative proportions according to the intended use, should preferably guide the selection of all materials necessary for the compositions disclosed herein. Method of preparation In another aspect of the present invention, there is provided a method for preparing a dermatological composition comprising nano-elements having a core made of a water-insoluble collagen-synthesis stimulating compound (CSSC), the core including in particular embodiments a water-insoluble collagen-synthesis stimulating polymer (CSSP), and a shell made of fatty amines, the core-shell nano-elements being dispersed as a nano-suspension in a polar liquid. The properties and characteristics of the materials used in the present method are as described above for each of the materials. The steps of the present method are briefly displayed in Figure 1 and further detailed hereinbelow, a step having a dashed contour being optional. In a first step (SOI) of the method, at least one CSSC (e.g., at least one CSSP) is provided. In a second step (S02) of the method, the CSSC(s) is / are mixed with at least one fatty amine. The CSSC(s) can be additionally mixed with one or more non-volatile liquid(s), whereby the CSSC(s) undergo(es) plasticizing or swelling by the liquid. The addition of the non-volatile liquid(s) is optional as the viscosity of the CSSC(s) provided in SOI can be sufficiently low for further processing (e.g., 107 mPa s or less, as measured at a temperature of 50°C and a shear rate of 10 sec'1), or the fatty amine(s) mixed therewith may sufficiently plasticize the CSSC(s), if so desired. The mixing of the CSSC(s) with the fatty amine(s) and any additional agent, such as the optional plasticizing liquid(s), can be performed at any suitable mixing temperature and / or mixing pressure suitable for such compounding. The temperature at which the mixing (which may include a plasticizing of the CSSCs) is performed is typically selected according to temperatures characterizing the substances involved in the process, for instance, by taking into account a Ts. Tm and / or Tg characterizing the CSSC(s) and, optionally, a Tb of the fatty amine(s) (referred to as Tba) and / or a Tb of the non-volatile liquid(s) (referred to as Tbi) and / or the degradation point(s) of the fatty amine(s). As previously detailed, a mixing temperature would suitably be higher (e.g., by at least 10°C, at least 15°C, or at least 20°C) than at least one of the characterizing temperatures of the CSSC(s) and lower (e.g., by at least 5°C, at least 10°C, at least 15°C, or at least 20°C) than the lowest of the boiling temperature and / or degradation point of the fatty' amine and / or the boiling temperature of the non-volatile liquid at a pressure the mixing step is performed, though this upper limit is not essential as long as the selected mixing temperature does not significantly boil away or degrade any of the materials to be mixed with the CSSCs so as to form the cores of the nano-elements. Hence, in some cases, the mixing temperature can even be at Tba, Tbi, or the fatty amine degradation point if the step is brief enough and / or the non-volatile liquid in sufficient excess and / or the mixing performed in a chamber sufficiently sealed to limit its evaporation / favor its condensation back to the mixture. One can readily appreciate that a change in the properties of the substance reflected by these temperatures dropping from first to second values can alternatively take place at a lower mixing temperature or a higher mixing temperature, if the pressure in a sealed chamber hosting the mixing process ensuring plasticization of the CSSC(s) were to be accordingly reduced or increased. Therefore, while in the description of a method suitable for the preparation of a composition according to the present teachings, reference can be made to specific temperatures and duration of times assuming the process is c arried out under standard atmospheric pressure, such guidance should not be viewed as limiting, and all temperatures and durations achieving a similar outcome with respect to the behavior of the plasticized CSSC(s) are encompassed. It is noted in this context, when the CSSC is a CSSP, that while the Tm and / or Tg of a polymer may set relatively clear temperatures below and above which a polymer may display a distinct behavior, this typically does not apply to the Ts. In view of their viscoelastic properties, a polymer or a plasticized polymer may remain “sufficiently solid” even at a temperature moderately higher than its formal softening point. The mixing or plasticizing can be performed under a variety of conditions, such as elevated temperatures (i.e., 30°C or more, e.g., at 40°C or more, at 50°C or more, at 60°C or more, at 75°C or more, or at 90°C or more) and / or elevated pressure (i.e., 100 kPa or more, e.g., at 125 kPa or more, 150 kPa or more, 175 kPa or more, 200 kPa or more, 250 kPa or more, or 300 kPa or more). As the mixing step often achieves at least some plasticizing of the CSSC, it may also be referred to as a plasticizing step the aforesaid temperatures and / or pressures typically accelerating the plasticizing process (i.e., shortening the duration of the plasticizing period) or enabling a desired modification of a boiling temperatures Tba or Tbi at which the fatty amine or the non-volatile liquid might evaporate. As mixing at elevated pressure increases Tba and / or Tbi the range of temperatures at which plasticizing could be performed can be accordingly widened. Conversely, plasticizing the CSSC under conditions less favorable than arbitrarily set to assess the ability of a CSSC to be plasticized by a specific agent, such as at a temperature of less than 50°C and / or a reduced pressure of less than 100 kPa, may prolong the plasticizing process, if desired. The ability of a CSSC to be plasticized or swelled by a particular plasticizing agent may be assessed under any one of the above temperature or pressure conditions. Mixing of the CSSC(s) with the fatty amine(s) and optionally the non-volatile liquid(s) by agitating the mixture can also shorten the plasticizing period, such agitating additionally ensuring that all parts of the CSSC(s) are plasticized in a relatively uniform manner, the plasticized CSSC behaving reasonably homogeneously with respect to subsequent steps of the method and results expected therefrom. If excess of the non-volatile liquid is used during the plasticizing process, it can be optionally removed before proceeding to following step(s). When the materials to be plasticized have a relatively high viscosity, the mixing step can also be referred to as compounding, and the mixing equipment can be accordingly selected. The dur ation of plasticizing will inter alia depend on the CSSC(s) being plasticized, the non-volatile liquid(s) being used, the plasticizing conditions (e.g., temperature, pressure, and / or agitation), and the desired extent of plasticizing. The plasticizing period can be of at least 1 minute and at most 4 days. In some embodiments, additional materials may optionally be incorporated within the CSSC(s) and added during the mixing step S02. These materials, which are typically insoluble in the polar carrier, can be at least one polar-carrier-insoluble surfactant, the surfactant(s) serving as an emulsifier, and / or at least one polar-carri er-insoluble active agent, the active agent(s) enhancing or modifying the biological activity of the composition, or any desirable additive. The mixing conditions may be adapted to the presence of such additional constituents. As mentioned, the addition of any one of the above agents is optional, based on the requirements of the process as well as of the final composition. Accordingly, the addition of these agents is marked by a dashed contour as an optional step S02’ of Figure 1. The mixing may be performed by any method known to the skilled artisan, such as: sonication, using a double jacket planetary mixer or extruder, etc. When the materials being mixed have a relatively high viscosity, the mixing step can be performed with a two-roll mill, a three-roll mill and such type of equipment. In a particular embodiment, the mixing is performed by sonication. In a third step (S03) of the method, the mixture of the CSSC(s) and fatty amine(s) (optionally further containing at least one non-volatile liquid and / or at least one surfactant and / or at least one carrier-insoluble active agent) is combined with at least one polar carrier. At least one surfactant can be added, if desired, at this step, the surfactant being a relatively polar emulsifier or a hydrotrope. Additional materials which are soluble in the polar carrier could also be added at this step but may equally be introduced after the following nano-sizing step. The mixture is nano-sized in a fourth step (S04) to form a nano-suspension, whereby nano-elements having a core including the CSSC(s) and optionally containing other polar-carrier-insoluble materials and a shell including the fatty amine(s) (and optionally some surfactants or other materials having a hydrophobic tail and a hydrophilic head capable of integrating the shell with the amine moieties of the fatty amines) are dispersed in a polar liquid including the polar carrier optionally combined with other polar materials. The nano-emulsion so produced may be “self-emulsified”, so that no dispersing agent need to be added to obtain the dispersion of the sought core-shell nano-droplets. Without wishing to be bound by theory, it is believed that the present method embeds at least a portion of the hydrophobic tails of the fatty amines (or an hydrophobic moiety of any other carrier insoluble material mixed with the CSSC), naturally oriented towards the hydrophobic core, while the amine heads of the fatty amines (or the hydrophilic moieties of additional suitable materials) turn towards the polar carrier, forming the shell surrounding the core. The method therefore allows the preparation of nano-droplets having hydrophobic cores of the CSSC (optionally with a non-volatile liquid and / or a carrier-insoluble active agent), surrounded by the amine heads pointing outwardly, forming the first shell, the nano-droplets being dispersed within the polar carrier. As the amine groups of the shell can be charged by the polar liquid, the similarly charged nano-droplets can repulse one another, remaining accordingly dispersed. As the nano-sizing is typically performed by applying shear at a relatively elevated temperature, the core-shell nano-elements including the CSSC(s) are generally nano-droplets during that step and the resulting nano-suspension is a nano-emulsion. The nano-emulsion can be obtained by nano-sizing the mixture of desired materials by any method capable of shearing the CSSC (whether plasticized or not, or including additional compounds), the shearing method being selected from the group comprising: sonication, milling, attrition, high pressure homogenization, high shear mixing and high shear microfluidization. In a particular embodiment, the nano-sizing is performed by sonication. The nano-sizing is performed at a shearing temperature that is at least equal to at least one of the first Ts, Tm and Tg of the CSSC, at least equal to at least one of the second Ts, Tm and Tg of the CSSC if plasticized, and can be, in some embodiments, at least 5°C higher, at least 10°C higher, or at least 15°C higher than the highest characterizing temperature of the CSSC mix being sheared. However, while this is not essential if the shearing step is brief enough and / or the polar liquid in sufficient excess, the shearing temperature should preferably prevent significant amounts of the liquid phase being boiled away and avoid a significant degradation of the fatty amine(s). In some embodiments, the nano-sizing temperature at which shearing is performed does not exceed at least one of the boiling temperature of the liquid phase in which the shearing is being performed (or of any other liquid the evaporation of which should be prevented) and the degradation point of the fatty amine(s) (or the temperature withstood by of any other material the thermal degradation (e.g., deactivation, destruction, etc.) of which should be prevented). Thus, the shearing temperature is generally lower than the lowest of the Tb of the polar carrier(s) (referred to as Tbc) and the degradation point(s) of the material(s) mixed with the CSSC at a pressure the nano-sizing step is performed. For instance, when the polar carrier is water, the shearing temperature can be selected to be lower than 95°C, lower than 90°C, lower than 85°C, or lower than 80°C, assuming the nano-sizing is performed at atmospheric pressure. However, if the nano-sizing were to be performed at an elevated pressure, the Tbc of the polar carrier would be raised and the shearing temperature could be accordingly increased. Still illustrating with water, while its Tb is 100°C at about 100 kPa, this boiling temperature raises to 120°C at about 200 kPa, in which case the nanosizing temperature not to be exceeded could be of up to 115°C. As mentioned, these upper limits, while preferred, are not essential, as any boiling away or degradation of a part, e.g., of the polar carrier or fatty amine(s) could be prevented at even higher temperatures if the step is brief enough, and / or the polar carrier in sufficient excess and / or the nano-sizing is performed in a chamber sufficiently sealed to limit its evaporation / favor its condensation back to the nano-suspension. At shearing temperatures in this range of higher than Ts, Tm or Tg and optionally lower than Tbc of the liquid carrier or degradation temperatures of suitable fatty amines, the CSSC(s), and in particular the CSSP(s), can completely melt and the nano-sizing process can be considered as “melt nano-emulsification”. In a fifth step (S05) of the method, the nano-emulsion may be optionally actively cooled down to a temperature below the Tm, Ts or Tg of the CSSC (or plasticized CSSC), to accelerate the relative solidification of the core-shell nano-elements, if desired in manufacturing. Such cooling can be actively achieved by refrigerating the nano-suspension (e.g., placing in a coolant having a desired low temperature), by subjecting the nano-suspension to ongoing agitation to accelerate heat dissipation (and incidentally maintain proper dispersion of the nano-droplets as they cool down), or by combining both approaches. This step is optional, as the nano-emulsions may be allowed to passively cool down without any agitation upon termination of nano-sizing. The nano-emulsions may also be passively cooled when combined with water (pH-modified water) and / or a polar-carrier-soluble active agent in subsequent optional steps, provided they are at sufficiently low temperature that would allow cooling of the nano-emulsion. Figure 3 schematically depicts a core-shell nano-particle 300 in a non-aqueous polar carrier, the absence of water preventing the charging of the amine heads of the fatty amines. The uncharged nano-element contains a core 310, composed of a CSSC and optionally of a non-volatile liquid and / or carrier-insoluble surfactant and / or carrier-insoluble active agent, the core entrapping at least part of the hydrophobic tails 314 of the fatty amines. The polar heads 322 of the fatty amines, represented by a circled “N” (encompassing primary, secondary and tertiary amine), are pointing away from the core’s surface 312, forming the nano-element’s shell 320. In some embodiments, at least 50% of the total number (Dn50) or volume (Dv50) of the core-shell nano-elements (e.g., nano-droplets or nano-particles) formed in this nano-sizing step have a hydrodynamic diameter of up to 200 nm, up to 190 nm, up to 175 nm, up to 150 nm, up to 125 nm, or up to 100 nm, up to 90 nm, up to 80 nm, or up to 70 nm. In some embodiments, the median diameter of the nano-elements is at least 5 nm, at least 10 nm, at least 15 nm, or at least 20 nm. Advantageously, such values are applicable as determined by the number of the core-shell nano-elements, and are generally measured at room temperature. As readily appreciated, depending on the temperatures characterizing the materials of the nano-elements and / or on the temperature at which measurements may be performed, the coreshell nano-elements can either be relatively liquid nano-droplets or relatively solid nanoparticles, as the temperature is reduced. The size of the nano-particles at room temperature is commensurate with the size of the nano-droplets or slightly more compact, their median diameter not exceeding 200 nm. In some embodiments, the size of the core-shell nano-particles or nano-droplets is determined by microscopy techniques, as known in the art (e.g., by Cryo TEM). In some embodiments, the size of the nano-elements is determined by Dynamic Light Scattering (DLS). In DLS techniques the particles are approximated to spheres of equivalent behavior and the size can be provided in term of hydrodynamic diameter. DLS also allows assessing the size distribution of a population of nano-elements. Distribution results can be expressed in terms of the hydrodynamic diameter for a given percentage of the cumulative particle size distribution, either in terms of numbers of particles or volumes, and are typically provided for 10%, 50% and 90% of the cumulative particle size distribution. For instance, D50 refers to the maximum hydrodynamic diameter below which 50% of the sample volume or number of particles, as the case may be, exists and is interchangeably termed the median diameter per volume (Dv50) or per number (Dn50), respectively, and often more simply the average diameter. In some embodiments, the nano-elements of the disclosure have a cumulative particle size distribution of D90 of 500 nm or less, or a D95 of 500 nm or less, or a D97.5 of 500 nm or less or a D99 of 500 nm or less, i.e., 90%, 95%, 97.5% or 99% of the sample volume or number of particles respectively, have a hydrodynamic diameter of no greater than 500 nm. In some embodiments, the cumulative particle size distribution of the population of coreshell nano-elements (e.g., nano-particles) is assessed in term of number of particles (denoted Dn) or in term of volume of the sample (denoted Dv) comprising particles having a given hydrodynamic diameter. Any hydrodynamic diameter having a cumulative particle size distribution of 90% or 95% or 97.5% or 99% of the particles population, whether in terms of number of particles or volume of sample, may be referred to hereinafter as the “maximum diameter”, i.e., the maximum hydrodynamic diameter of particles present in the population at the respective cumulative size distribution. ft is to be understood that the term “maximum diameter” is not intended to limit the scope of the present teachings to nano-particles having a perfect spherical shape. This term as used herein encompasses any representative dimension of the particles at cumulative particle size distribution of at least 90%, e.g., 90%, 95%, 97.5% or 99%, or any other intermediate value, of the distribution of the population. The core-shell nano-particles or nano-droplets may, in some embodiments, be uniformly shaped and / or within a symmetrical distribution relative to a median value of the population and / or within a relatively narrow size distribution. A particle size distribution is said to be relatively narrow if at least one of the following conditions applies: A) the difference between the hydrodynamic diameter of 90% of the nano-elements and the hydrodynamic diameter of 10% of the nano-elements is equal to or less than 250 nm, equal to or less than 200 nm, equal to or less than 150 nm, or equal to or less than 100 nm, which can be mathematically expressed by: (D90 - D10) <250 nm and so on; B) the ratio between a) the difference between the hydrodynamic diameter of 90% of the nano-elements and the hydrodynamic diameter of 10% of the nano-elements; and b) the hydrodynamic diameter of 50% of the nano-elements, is no more than 2.5, no more than 2.0, no more than 1.5, or even no more than 1.0, which can be mathematically expressed by: (D90 - D10) / D50 <2.5 and so on; and C) the poly dispersity index of the nano-elements is equal to or less than 0.5, equal to or less than 0.4, equal to or less than 0.3, or equal to or less than 0.2, which can be mathematically expressed by: PDI = <r / d2 <0.5 and so on, wherein tr is the standard deviation of the particles distribution and d is the mean size of the particles, the PDI optionally being equal to 0.01 or more, 0.05 or more, or 0.1 or more. The PDI information is generally readily obtained from the instrument used to measure the hydrodynamic diameter of the nano-particles. When the nano-elements are electrostatically charged, preferably positively charged, this facilitates their further coating by an external shell of carrier-soluble active agents suitably having an opposite charge, the resulting core-multi-shells forming moderately charged (generally negatively) or even uncharged nano-elements. The skin’s surface is generally negatively charged, and therefore the overall charge of the nano-elements contributed inter alia by the CSSCs of the cores, the fatty amines of the first shells and the active agents may modulate the efficacy of skin penetration. It is believed that nano-elements moderately positively charged (regardless of the number of shells) would have a slower rate of transdermal delivery than negatively charged nano-elements (e.g., typically core-multi-shells nano-elements sufficiently surrounded by a negatively charged active agent). Negatively charged nano-elements may experience a slight repulsion when transiting via the skin, this phenomenon pushing them further “down” across the skin. Without wishing to be bound by theory, it is believed that the charge of the nano-elements having at first only a single shell is mainly contributed by the amine heads of the fatty amines. When exposed to an aqueous environment, the fatty amine heads become positively charged due to protonation of the amine group, the protons being donated from the water. Hence, when the polar carrier is an aqueous polar carrier (e.g., water, or an aqueous mixture), the nanoelements can develop a positive charge. However, when a non-aqueous polar carrier is used during the preparation of the nanoelements, a coordinate bond is believed to form with the amine heads, a polar carrier unable to protonate the molecules of the first shell “masking” any positive charge that may have otherwise potentially developed on the surface of the core-shell nano-elements in presence of a liquid enabling protonation. In such case, or when the positive charge detected in the liquid carrier is deemed insufficient, un-masking of the charge or its increase may be performed by replacing at least part of the polar carrier by water (such as, by combining the nano-suspension with water), thus creating an aqueous environment wherein the charge can be made available. While the water itself is capable of creating an environment wherein protons are available to some extent for creating a positive charge on the amine heads, a pH-modifying agent, preferably an acid, may be added to further promote protonation. The acid is believed to react with the polar carrier molecules (supposedly by hydrogen bonding), distancing them from the shell surface of the nano-particles, and leaving the amine heads exposed to the proton-rich aqueous environment, thus allowing the formation of a positive charge on the shell surface. Alternatively, a base may be added to the polar carrier, contributing to the positive charging of the amines, even if slightly less than an acidic agent, a basic pH-modifying agent optionally contributes to the negative charging of a carrier-soluble active agent if added to the composition. Such addition of an acid or a base to the nano-suspension may be referred to as “acid doping” or “base doping”, respectively. The negative charge of materials due to form a second shell, whether or not enhanced by doping, is expected to promote their attraction to the positively charged core-shell nanoelements, facilitating the formation of core-multi-shells nano-elements via non-covalent electrostatic charges. Alternatively, or additionally, the active agents of the second shell may be selected to covalently bind to materials of the first shell (e.g., fatty amines, surfactants, etc.). The amount of the pH-modifying agent added to the composition should be controlled, so as to create an environment that keeps the balance between a sufficient positive charging of the fatty amines, and a sufficient negative charging of the carrier-soluble active agent, their respective opposite charges being adequate for attraction of one to the other. For instance, the amount of an acidic agent should be sufficiently high to allow optimal positive charging of tire amine heads, but sufficiently low so as to keep the carrier-soluble adequately negatively charged. As the size of par ticles decreases, their specific surface area increases, hence the amount of materials that may be present on their outer surfaces. As the nano-elements of the present invention are characterized by a Dn50 of 200 nm or less, in some embodiments, the nanoelements can be sufficiently small to reach a specific surface area that is high enough to allow the presence of enough amine heads in the shell being able to contribute to a desirable positive charge of the nano-dispersion. In such case, the use of a pH-modifying agent, which may be used to further boost a charge, can be superfluous (as demonstrated in Example 4 below with HC1 as the pH-modifying agent). When the polar carrier added in Step S03 for the sake of nano-sizing is non-aqueous, the method may optionally include a sixth step (S06 of Figure 1), whereby replacement of at least part of the polar carrier by water or pH-modified water is carried out. As previously described, when the polar carrier is water or a mixture thereof with a non-aqueous polar carrier, such replacement step may not be necessary. Alternatively, an aqueous pH-modified solution of the polar carrier may be utilized in the third step of the method (S03 of Figure 1), resulting in hydrogen ions being present in the mixture, allowing for the protonation of the amines group of the fatty amines, whereby a possible masking effect of the polar carrier is at least partially avoided. In some embodiments, the pH-modifying agent is added in an amount resulting in the composition having a pH between 1 and 10, between 1 and 9, or between 1 and 8. In particular embodiments, the pH modifying agent is added in an amount which renders a pH of 7 and less, 6 or less, 5 or less, or 4 or less. In some embodiments, the core-shell nano-elements have a charge of +5 mV or more, +10 mV or more, +20 mV or more, +30 mV or more, or +40 mV or more, when placed in an aqueous environment. The core-shell nano-elements described above may be formulated into a dermatological composition and administered to the skin of a mammalian subject to promote, inter alia. collagen synthesis. Alternatively, the core-shell nano-elements can be used as nano-carriers for other active agents. Hence, in an optional seventh step of the method (S07 of Figure 1), a carrier-soluble active agent is added to the core-shell nano-elements previously obtained. The active agents that are added can envelop the outer surface of the core-shell nano-elements, forming a second shell. The second shell may be covalently and / or non-covalently attached to the first shell. Such nano-elements can be referred to as core-multi-shells nano-elements, or core-shells nanoelements or active agent-coated core-shell nano-elements. The amount of the carrier-soluble active agent to be added to the nano-suspension (optionally being a nano-dispersion) may depend inter alia on the particle size of the nanoelements and the surface area accordingly available to attachment. Moreover, the respective zeta potentials of the core-shell nano-elements and of the carrier-soluble active agent may also indicate the respective proportions they can be present at in the composition to optimize the formation of the core-multi-shells nano-elements, avoiding if desired the presence of excess active-agents in the polar carrier. While such excess is permitted, in particular as long as promoting a stabilization of the second shell, too much of unbound active agents can be superfluous if the molecules of the carrier-soluble active agents have a high molecular weight precluding their transdermal delivery, if desired. The attachment of the carrier-soluble active agent to the core-shell nano-elements is enabled or promoted as a result of a difference in zeta potential between the zeta potential (£1) of original core-shell nano-elements, induced by the fatty amines of the first shell, and the zeta potential of the active agent (^2), due to form the second shell. In some embodiments, the absolute value of the zeta potential differential (AQ defined as A£ = - Q| is at least 5 mV, at least 10 mV, at least 15 mV, at least 20 mV, at least 25 mV, or at least 30 mV, as measurable in the presence of water or an aqueous polar carrier. In some embodiments, the active agent-coated nano-elements of the present invention have an average hydrodynamic diameter Dn50 of 200 nm or less, 190 nm or less, 175 nm or less, 150 nm or less, 125 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, or 70 nm or less. In some embodiments, the Dn50 of the active agent-coated core-shell nano-elements is 5 nm or more, 10 nm or more, 15 nm or more, or 20 nm or more. Figure 4 schematically depicts such a core-multi-shells nano-particle 400, coated with a carrier-soluble active agent, in an aqueous environment. Similar to the nano-particle 300 previously described in Figure 3, nano-particle 400 is composed of a core 410, in which at least part of the hydrophobic tails 414 of the fatty amines are embedded. Unlike nano-particle 300, which is dispersed in a non-aqueous polar carrier, the aqueous environment, in which nano-particle 400 is dispersed, allows for the polar heads of the fatty amines 422 to be positively charged, forming a now positively charged nano-particle first shell 420, surrounding the core’s surface 412. This charging of the first shell allows the attachment of carrier-soluble active agent molecules 432 to the surface of the nanoparticle first shell 422, resulting in the formation of a second shell 430 comprising the active agent, wherein the AC between the active agent and the first shell of the nano-elements is as described above. The active agent molecules may be negatively charged, resulting in a relatively larger AC between the first shell 420 of the nanoparticle, being positively charged, and the active agent molecules 432. Alternatively, the active agent molecules may be positively charged, resulting in a relatively smaller AC, and a relatively weaker attraction compared to negatively charged molecules. Yet, as long as the AC is of 5 mV or more, the conditions are sufficient for the formation of the second shell 430. In particular embodiments, the carrier-soluble active agent molecules are negatively charged. While in the method detailed above, some ingredients have been described as being introduced (or optionally introduced) in the composition at a particular step, this should not be construed as limiting. For instance, skin-penetration enhancers may, depending on the material they are selected from, be added with the non-volatile liquid during optional step S02’, if performed, or with the polar carrier during step S03, or to the liquid polar phase of the nanoemulsion as currently described in optional step S06. Alternatively, such agents may be omitted, provided that the nano-elements including the CSSC core can be transdermally delivered in an amount sufficiently effective for the sought effect. Thus, the above-described steps can be modified, omitted (e.g., S02’, S05, S06 or S07) and additional steps may be included. For instance, the dermatological composition may comprise any additive customary to cosmetical or pharmaceutical compositions, such as moisturizers, emollients, humectants, UV-protective agents, thickeners, preservatives, antioxidants, bactericides, fungicides, chelating agents, vitamins and fragrances, the nature and concentration of which need not be further detailed herein. The additives may be added during steps of the method already described or via new steps. Furthermore, the composition may be further treated (e.g., sterilized, filtered, etc.) in accordance with health regulations, to make it suitable for dermatological uses, in particular on human skin. Advantageously, the present method does not seek to chemically modify its active ingredients, as might have been required for instance to jointly attach them when preparing implants. The absence of such modifications in the present compositions is expected to prevent formation of large particles that would be unable to pass the skin barrier, and / or believed to prevent an undesirable decrease in the biological activity these ingredients might provide in their native (unmodified) form, assuming they successfully penetrated the skin. hi other aspects, there are provided cosmetic or therapeutic uses of the present dermatological compositions for inter alia improving skin appearance of a subject, as enabled by the delivery of efficacious amounts of the CSSCs and optional active agents. These uses encompass all activities such CSSCs are known or will be found to have when delivered to the skin, included by injection, the present invention advantageously allowing such uses to be additionally implemented by topical application of the compositions. Preparation of the dermatological compositions for such uses and their mode of application can be conventionally conducted and implemented, and need not be detailed herein. EXAMPLES Materials The materials used in the following examples are listed in Table 1 below. The reported properties were retrieved from the product data sheets provided by the respective suppliers or estimated by standard methods. Unless otherwise stated, all materials were purchased at highest available purity level. N / A means that a particular information is not available. Table 1 Component Chemical Name Product Name Supplier CAS No. cssc Polycapro lactone Polycaprolactone, MW~14kDa Sigma Aldrich, USA 24980-41-4 Fatty amines N,N-Dimethyl-dodecylamine DMDA Sigma Aldrich, USA 112-18-5 Cetrimonium chloride CTAC Sigma Aldrich, USA 112-02-7 Oleyl amine Oleyl amine Arcos Organics, USA 112-90-3 Octyl amine Octyl amine Sigma Aldrich, USA 111-86-4 N,N-Bis-(2-hydroxy ethyl) C12-C18-alkylamine Genamin® C 020 Clariant, Switzerland 71786-60-2 Non-volatile liquid Dibutyl adipate Cetiol® B BASF, Germany 105-99-7 Triethyl O-acetylcitrate Citrofol® All Jungbunzkauer, Switzerland 77-89-4 Polar carriers Glycerol Glycerol Sigma Aldrich, USA 7325-17-9 Propylene glycol Propylene glycol Chen Shmuel Chemicals, Israel 57-55-6 Surfactants Mixture of: olive oil and glutamic acid Olivoil® glutamate Kalichem, Italy 67762-27-0 8005-44-5 31566-31-1 Sodium dioctyl sulfosuccinate Sodium dioctyl sulfosuccinate (AOT) Sigma-Aldrich®, USA 577-11-7 pH-modifying agents Acetic acid Acetic acid (99.8%) Chen Shmuel Chemicals, Israel 64-19-7 Hydrochloric acid HC1(1M) Sigma Aldrich, USA 7647-01-0 Component Chemical Name Product Name Supplier CAS No. Lactic acid Lactic acid Chen Shmuel Chemicals, Israel 79-33-4 Water-soluble active agents Sodium hyaluronate Low molecular weight hyaluronic acid (LMW HA, MW 3 kDa) Xi'an Lyphar Biotech, China 9067-32-7 L-ascorbic acid Vitamin C Sigma Aldrich, USA 50-81-7 Collagen peptides Verisol® Gelita, Germany 92113-31-0 Elastin Elastin Koken, Japan 9007-58-3 Equipment Oven: DFO-240, by MRC, Israel Thermo-rheometer: Thermo Scientific (Germany) Haake Mars III, with a C20 / 10 spindle, a gap of 0.052 mm, and a shear rate of 10 sec'1 Sonicator: VCX 750, by Sonics &Materials, USA Dynamic Light Scattering and Zeta Potential measurement: Malvern Zetasizer Nano ZS, Malvern Instruments Ltd., UK Conductivity meter: Eutech CON 700 by Thermo Fisher Scientific, USA CryoTEM: Talos 200C by Thermo Fisher Scientific, USA, with a Lacey grid Example 1: Reducing viscosity of the CSSC In the present study, the viscosity of a CSSC being polycaprolactone (PCL) and of its mixtures with a non-volatile liquid or fatty amines, used as plasticizing agents, were measured at different weight per weight ratios of the PCL to the plasticizing agents. PCL and a non-volatile liquid or a fatty amine at various weight per weight ratios were combined in a glass vial and the sealed vials were placed in an oven pre-heated to 80°C. The PCL:non-volatile liquid ratios tested were 1:1 and 1:2.33 and the PCL:fatty amine ratios tested were 1:0.1,1:0.33, 1:0.5 and 1:1. Following 1 hour of incubation under heat, the contents of the vials were mixed by hand for about 30 seconds, until clear solutions were obtained. The samples were allowed to cool down overnight (i.e., at least 12 hours) at room temperature so as to solidify. None of the plasticizing agents so tested displayed leaching out of the solidified polymer, suggesting that they might be used at even higher proportion with respect to the PCL. Solid samples were then transferred to a rheometer where their respective viscosity was measured as a function of temperature between room temperature and 70°C at a ramping up temperature of 10°C / min. The viscosities (or 2nd viscosities) of the samples as measured at 50°C and 70°C are summarized in Table 2, including the viscosities of a reference sample made of 5 PCL alone, unplasticized. Table 2 Plasticizing agent PCL:pIasticizing agent ratio PCL 2nd viscosity at 50°C [mPa-s] PCL 2nd viscosity at 70°C [mPa’s] None N / A 50 1.7xl05 70 7.0x104 Cetiol® B IT 50 5.0x103 70 2.2 xlO3 1:2.33 50 215 70 164 Oleyl amine 1:0.33 50 1.9x103 70 1.7x103 1:0.5 50 6.7x103 70 4.4xl03 1:1 50 544 70 279 As can be seen from the table, at the temperatures of 50°C and 70°C, all of the materials tested as plasticizing agents (either the non-volatile liquids dedicated to this purpose or the fatty amines inherently contributing to this effect) decreased viscosity of the PCL to less than 104 10 mPas. Based on the above results, ratios of PCL:plasticizing agents providing a dynamic viscosity of IxlO4 mPa s or less, as measured at least at 50°C, were selected for the preparation of core-shell nano-particles to be used in topical compositions, as detailed in the following examples. 15 Example 2: Preparation of CSSC / fattv amine nano-dispersions 2 g of PCL, 2 g of the fatty amine N,N-dimethyldodecylamine (DMDA) and 6 g of the non-volatile liquid Cetiol® B, serving as a dedicated plasticizer, were placed in a 20 ml glass vial. The vial contents were sonicated for 2 minutes at about 70°C until a clear CSSC / fatty amine premix including the non-volatile liquid was obtained. In a separate 20 ml glass vial, 8 g of glycerol wrere heated to about 70°C using a sonicator, followed by addition of 2 g of the hot premix prepared above, and the composition was sonicated for 5 minutes whilst maintained at 70°C to obtain a nano-emulsion. The nano-emulsion was allowed to cool down to room temperature until a nanodispersion containing core-shell nano-particles was obtained. This nano-dispersion (ND1) is reported in Table 3, which presents additional nanodispersions prepared according to similar procedures, each nano-dispersion containing different components in different amounts, and prepared under different conditions, as specified in the table. The values reported in the table correspond to the concentration of each component in weight percent (wt.%) by total weight of the nano-dispersion, except for the values in the CSSC / fatty amine premix section, which correspond to the weight percentage of each component in that particular premix which may further include a non-volatile liquid. Water refers to double distilled water. The size of the nano-particles so produced was measured by Dynamic Light Scattering (DLS) on samples of the compositions, diluted to 1:100 in water, and the measured median diameter per number (Dn50), as well as polydispersity indices (PDI), are also presented in the table below. The maximum hydrodynamic diameters below which 10% and 90% of the sample number of particles exist (Dn10 and Dn90, respectively) are also presented in the table for some of the obtained nano-suspensions. Table 3 Component Composition ND1 ND2 ND3 ND4 ND5 ND6 CSSC / fatty amine premix PCL 20 30 20 20 20 20 DMDA 20 20 CTAC 3 Genamin® C 020 20 20 Oleyl amine 20 Cetiol® B 60 67 60 60 60 60 Component Composition ND1 ND2 ND3 ND4 ND5 ND6 Premix preparation 2 min @70°C 1 min @80°C Nano-dispersion PCL 4 6 2 4 4 8.9 DMDA 4 2 CTAC 0.6 Genamin® C 020 4 4 Oleyl amine 8.9 Cetiol® B 12 13.4 6 12 12 Citrofol® All 26.7 Olivoil® glutamate 20 Sodium dioctyl sulfosuccinate 1.7 Glycerol 80 90 Propylene glycol 10.1 Water 80 60 78.3 45.4 Nano-sizing 5 min @70°C min @80°C Dn10 [nm] 117 57.4 75.6 N / A N / A N / A Dn50 [nm] 176 78.3 100 50.4 98.7 N / A Dn90 [nm] N / A 126 293 N / A N / A N / A PDI 0.277 0.460 0.477 0.224 0.151 N / A As can be seen in Table 3, the present method is suitable to prepare nano-suspensions of core-shell nano-elements containing a CSSC and a fatty amine, the nano-elements having a Dn50 not exceeding 200 nm, this value being even lower than 100 nm for some of the nanosuspensions reported above. The PDI of the populations of the core-shell nano-elements was at 5 most about 0.5. Representative results of particle size distribution in a sample of ND3, showing the percentage (per number) of PCL / DMDA core-shell nano-particles having hydrodynamic diameters in the range of 10-1,000 nm, are presented in Figure 2. Example 3: Preparation of positively charged core-shell PCL / DMDA nano-particles by acid-doping 8 g of double distilled water were placed in a 20 ml glass vial. 2 g of the nano-dispersion ND I obtained in Example 2 were added, and the contents of the vial were shaken by hand for about 10 seconds until a homogeneous mixture was obtained (referred to as charged ND1 or cNDl}. Zeta potential of the mixture was measured by Malvern Zetasizer Nano ZS and found to be -14.7 mV. Unless otherwise stated, all measurements made with this instrument (e.g., zeta potential and particle size distribution) were performed on samples diluted 1:100 in double distilled water. 1 drop of acetic acid was then added to the mixture, yielding a pH of 5.5 (as measured using a pH stick), and the vial was shaken by hand for about 10 seconds until a nano-dispersion containing positively charged core-shell PCL / DMDA nano-particles was obtained, referred to as cNDl The zeta potential of the nano-particles in the acid doped nano-dispersion was measured and confirmed to be positive with a charge of +52.4 mV. The hydrodynamic diameter of the nano-particles obtained in the acid-doped cNDl ’ was determined by DLS and the D\50 of the sample was found to be similar to that of the nanoparticles of ND I. indicated in Table 3. Example 4: Preparation of positively charged core-shell PCL / DMDA nano-particles., in absence of acid 9.9 g of double distilled water were placed in a 20 ml glass vial. 0.1 g of nano-dispersion ND3 obtained in Example 2 were added, and the contents of the vial were shaken by hand for 10 seconds until a homogeneous mixture, referred to as cND3, was obtained. The zeta potential of the mixture was measured and found to be +43 mV. The par ticle size distribution of the nanoparticles so obtained was determined by DLS and the sample was found to have a Dn50 similar to that of the nano-particles of ND3, indicated in Table 3. Example 5: Preparation of positively charged core-shell PCL / DMDA nano-particles by acid-doping of diluted sample 9 g of double distilled water were placed in a 20 ml glass vial. 1 g of the nano-dispersion cND3, obtained in Example 4 were added, and the contents of the vial were shaken by hand for 10 seconds until a homogeneous mixture, referred to as cND3 was obtained. The zeta potential of the mixture was measured and found to be -9.9 mV. This mixture differs from the one described in Example 4 by containing 10-times less ND3 in a same total weight of aqueous carrier. The 10-fold diluted nano-dispersion presently prepared displayed a relatively lower charging, having a charge of -9.9 mV, as compared to a charge of +43 mV in previous case. 1 drop of acetic acid was then added to the relatively diluted mixture, yielding a pH of 5.5 (as measured using a pH stick), and the vial was shaken by hand for about 10 seconds until an acid-doped nano-dispersion containing positively charged core-shell PCL / DMDA nanoparticles, referred to as cND3' ’, was obtained. The zeta potential of the acid-doped nanodispersion cND3 ’ ’ was measured and confirmed to be positive with a charge of +7.8 mV. The hydrodynamic diameter of the obtained nano-particles was determined and the Dn50 was found to be similar to that of the nano-particles of ND3, indicated in Table 3. Example 6: Preparation of positively chargeable core-shell PCL / DMDA nano-particles in an acidic polar carrier 2 g of PCL, 2 g of DMDA and 6 g of Cetiol ' B were placed in a 20 ml glass vial. The vial contents were sonicated for 2 minutes at about 70°C until a clear CSSC / fatty amine premix was obtained. In a separate 20 ml glass vial, 8 g of glycerol and 1 g of a 3 wt.% HC1 solution were mixed, whereby a solution having a pH of 3 was obtained (as measured by a pH stick). 1 g of the hot CSSC / fatty amine premix prepared above was added to the acidic liquid carrier, and the contents of the vial were sonicated for 30 seconds to obtain a nano-emulsion. The nano-emulsion was allowed to cool down to room temperature until a nanodispersion was obtained. The zeta potential of the nano-dispersion was measured and was found to be +72.8 mV, this charge resulting from the dilution of the sample in water. Hence, positively charged nanoparticles were readily obtained following their sonication in the acidic polar carrier, instead of a two-step process, as previously described. The nano-dispersion so obtained (ND7) is reported in Table 4, which presents additional nano-dispersions prepared according to similar procedures, all being chargeable in water, each nano-dispersion containing different components in different amounts, and prepared under different conditions, as specified in the table. The values reported in the table correspond to the concentration of each component in wt.% by total weight of the nano-dispersion, except for the values in the CSSC / fatty amine premixe section, which correspond to the weight percentage of each component in that particular premix. The zeta potential, DnIO, Dn50, Dn90 and PDI were measured in samples of some of the nano-dispersions, diluted to 1:100 in double distilled water, resulting in their charging, and the 5 values are presented in Table 4. Table 4 Component Composition ND 7 ND8 ND9 ND10 ND11 ND12 ND13 CSSC / fatty amine premix PCL 20 20 30 30 30 20 20 DMDA 20 20 12 Oleyl amine 25 25 20 Genamin® C 020 20 Cetiol® B 60 60 58 60 Citrofol® All 45 45 60 Premix preparation 2 min @70°C 1 min @70°C 1 min @80°C Nano-dispersion PCL 2 6 6 8.4 8.7 7.6 4 DMDA 2 6 2.4 Oleyl amine 7 7.2 7.6 Genamin® C 020 4 Cetiol® B 6 18 11.6 12 Citrofol® All 12.6 13.1 22.8 Glycerol 80 60 70 37 20.3 17.7 Propylene glycol 10 14.5 12.7 Water 9.7 9.7 9.7 24.2 35.1 30.7 79.9 HC1 0.3 0.3 0.3 0.8 1.1 0.9 Lactic acid 0.1 Nano-sizing 30 sec @70°C 1 min @80°C DnIO [nm] 55.3 77.4 95.4 58.3 N / A N / A N / A Component Composition ND 7 ND8 ND9 ND10 NIMI ND12 ND13 Dn50 [nm] 73.5 106 138 80.3 N / A N / A 73.4 Dn90 [nm] 106 186 238 134 N / A N / A N / A PDI 0.424 0.332 0.148 0.242 N / A N / A 0.202 Zeta potential [mV] +72.8 +73.0 +59.7 +48.9 N / A N / A N / A In addition to measuring the zeta potential of the nano-dispersions, the effect of the acid in the polar liquid carrier was monitored by measuring the pH changes along the preparation of the nano-dispersions. Taking ND7 for illustration, when combining an acidic glycerol solution having a pH of 3 with the CSSC / fatty amine mixture, the pH increased to 6, indicating the elimination of the hydrogen ions of the liquid carrier, which are believed to have reacted with the amine groups of the fatty amine shell. The pH remained at 6 after cooling and increased to 6.5 following dilution with water, indicating that the amine groups remain protonated, as confirmed by the positive zeta potential. Example 7: Preparation of core-shell nanoparticles coated with water-soluble active agents 1 g collagen peptides powder and 2.1g water were placed in a 20 ml glass vial and mixed at room temperature until complete dissolution. In a separate 20 ml vial, 6.9 g of the nano-dispersion ND! 1 obtained in Example 6 were placed, and the collagen solution was added. The contents of the vial were shaken by hand for 10 seconds until a homogeneous mixture was obtained. The composition of collagen-coated nano-elements so obtained (Collagen-NDl 1) is reported in Table 5, which also presents a composition of LMW HA-coated nano-elements (LMW HA-ND1similarly prepared. A reference composition containing uncoated nano-elements (Uncoated-cNDl L) was also prepared, comprising 3.1 g water lacking any carrier-soluble active agent. Another nano-dispersion was prepared, based on ND6 (referred to as LMWHA-ND6), to which LMW HA was added to achieve the concentrations described in Table 5. One sample of LMW HA-ND6 was prepared, wherein the LMW HA solution was mixed with the ND6 composition by sonication, and another sample was prepared by mixing the LMW HA solution with the ND6 composition by hand. These compositions are also reported in Table 5, wherein the different components and amounts are specified. The values reported in the table correspond to the concentration of each component in wt.% by total weight of the nano-dispersion. Dn50 and zeta potential values of each composition are also presented in Table 5. 5                                        Table 5 Component Composition Uncoated-ND11 Collagen-ND11 LMWHA-ND11 LMWHA-ND6 PCL 6 6 6 8.65 Oleyl amine 5 5 5 8.65 Citrofol® All 9 9 9 25.9 Glycerol 14 14 14 Propylene glycol 10 10 10 9.8 HC1 25 25 25 Collagen 10 LMW HA 1 2.9 Water 31 21 30 44.1 Dn50 [nm] 50.1 43.4 40.4 N / A Zeta potential [mV] +58.6 +43.6 +54.2 N / A As can be seen from the changes in zeta potential, the addition of active agents to previously prepared core-shell nano-particles decreased the charges at the newly formed outer surface of the nano-particles, in support of modifications at this interface with the liquid carrier. For reference, the zeta potential of 0.1 g of the collagen peptides dispersed in 9.9 g of distilled 10 water was found to be -7.7 mV, indicating a satisfactory Al between the zeta potential of the collagen intended to coat the nano-particles and of the nano-particles to be coated thereby, which allows the attachment of the collagen to the surface of the nano-particles. The zeta potential of a similarly prepared solution of LMW HA in water was measured and found to be -17 mV, resulting in an even higher AC compared to the one observed for the 15 preparation of the composition of collagen-coated nano-particles. The mixing speed of the carrier-soluble active agent forming the second shell is believed to contribute to the the form of the obtained core-shells nano-particles. Figure 5A shows a CryoTEM analysis of the first sample of composition LMW HA-ND6, obtained by high shear mixing (i.e., sonication) of the LMW HA with the core-shell nanoelements of ND6. In the figure, the cores 410 comprising the PCL, seen as dark globules, bear a second shell 430, composed of LMW HA. As can be seen in Figure 5A, the second shell can comprise a number of layers of the HA, formed one on top of the other. Figure 5B is another image captured by CryoTEM, of the second sample LMWHA-ND6 composition, wherein the LMW HA was mixed in manually. In the image, two dark PCL cores 410 can be seen surrounded by a mutual shell 430’, also composed of layers of the LMW HA, forming a larger nano-element. It is believed that manual mixing might be too slow / low energy, and the shells of the active agent formed on the cores coalesce and merge into such larger particles. Hence, it is suggested that high energy mixing (e.g., high shear) is more favorable than low energy mixing methods for the formation of second shells surrounding individual cores, such core-multi-shells nano-elements therefore having a particle size distribution commensurate with the size of the individual core-shell, more easily remaining within the ranges of size suitable for transdermal delivery. The core-shell nano-particles may be alternatively coated according to the present example with high molecular weight (HMW) HA, generally having a MW of 1 MDa. Similarly, the ND12 nano-particles, prepared in Example 6, were coated with various active agents, and an uncoated ND 12 composition was also prepared and used as reference. The AD72-based compositions, including their respective ingredients and concentrations thereof, are summarized in Table 6, the concentration of each components being provided in wt.% by total weight of the nano-dispersion. Table 6 Composition Uncoated-ND12 LMWHA-ND12 Vitamin C-ND12 Collagen-ND12 Elastin-ND12 PCL 6 6 6 6 6 Oleyl amine 6 6 6 6 6 Citrofol® An 18 18 18 18 18 Glycerol 14 14 14 14 14 Propylene glycol 10 10 10 10 10 HC1 25 25 25 25 25 Composition Uncoated-ND12 LMWHA-ND12 Vitamin C-ND12 Collagen-ND12 Elastin-ND12 LMW HA 0.5 Vitamin C 0.5 Collagen 1 Elastin 1 Water 21 20.5 20.5 20 20 Dn50 [nm] 72.2 67.5 66.1 72.8 61.6 Zeta potential [mV] + 66.6 + 50.8 + 44.5 + 33.5 + 39.9 Example 8: Conductivity measurements In order to further demonstrate the adsorption of the active agent to the surface of the core-shell nano-particles, conductivities of samples of the various compositions were measured using a conductivity meter and are presented in microSiemens (gS) in Table 7. The rationale for this study relies on the expectation that if two species are mixed, each independently having a conductivity as an electrolyte in a particular medium, the conductivity of the mixture is the sum of the relative contributions of the species, only if the species remain separate. In other words, if tire conductivity of a mixture of species is not the sum of the individual conductivities of its constituents, it can be assumed that the species interact one with the other. In the present case, it is assumed that the molecules of the active agent are able to attach to the core-shell nano-particles, so that when core-shell nano-particles having a conductivity A at a given concentration in a medium are mixed with an active agent having a conductivity B at a given concentration in substantially the same medium, the conductivity of the mixture should be lower than the combined conductivities A+B. Samples of the various active agents were prepared in a carrier being a mixture of liquids substantially similar to the one in which the nano-particles of ND12 and their coated versions were prepared. The conductivities of the active agents alone, of the core-shell nano-particles prior to coating by the second shell of active agents, and of the active agent-coated nanoparticles were measured and are all reported in Table 7. Table 7 Conductivity [pS] Sample contents Active agent in carrier only Uncoated nanoparticles Active agent-coated nano-particles LMWHA-ND12 401 735 651 Vitamin C-ND12 511 754 835 Collagen-ND12 104 720 521 Elastin-ND12 125 731 700 As can be seen from the above table, the conductivities of the uncoated nano-particles are substantially similar, as expected for similar samples of core-shell nano-partic les in a similar carrier, without any specific active agents. In contrast, the conductivities of each active agent alone, or of the core-shell nanoparticles coated thereby, depended on the active agent (e.g., LMW HA, vitamin C, collagen and elastin) being considered. Noticeably, the conductivities of all the samples of the active agent-coated nano-particles exhibited conductivities that were lower than the sum of: the conductivity ¢4) of the core-shell nano-particles in the carrier and the conductivity (5) of the active agent in substantially the same carrier. These results support that the present method enables the preparation of core shell nano-particles having a core made of a CSSC material, a first shell made of a fatty amine and a second shell, interacting with the first shell, the second shell being made of an active agent. Example 9: Patch test protocol for skin irritation analysis The irritating effect, if any, of topical compositions according to the present teachings, such as prepared in Examples 2-6, can be tested on skin of human volunteers by application of the formulations to be tested via a patch. Each volunteer applies a predetermined volume of a tested composition (e.g., 0.02 ml) in a small plastic cavity (e.g., of 0.64 cm2) of an occlusive patch with a filter tissue coming in contact with the skin of the volunteer in a predetermined body area (e.g., on the back). The patch is attached to the skin area by a hypoallergenic non-woven adhesive tape and the test formulation is kept in contact with the skin for 48 hours. The appearance of the treated area is assessed before the application of the topical compositions and 30 minutes after patch removal. Empty patches, lacking any composition, can serve as negative controls. Skin reactions (erythema, dryness and oedema) are scored throughout the test according to the following pre-defined scoring scale: Erythema 0 = no evidence of erythema; 0.5 = minimal or doubtful erythema; 1 = slight redness, spotty and diffuse; 2 = moderate, uniform redness; 3 = strong uniform redness; 4 = fiery redness Dryness (Scaling) 0 = no evidence of scaling; 0.5 = dry without scaling; appears smooth and taut; 1 = fine / mild scaling; 2 = moderate scaling; 3 = severe scaling with large flakes Oedema - = absence of oedema; + = presence of oedema The results obtained with any test composition are compared to those obtained on the control zone (naive skin surface under the empty patch) and the compositions classified as: nonirritant, very slightly irritant, slightly irritant, moderately irritant, irritant, or very irritant, according to the combined effect a composition has with respect to the aforesaid prospective skin reactions. Example 10: Effect of the compositions on facial skin appearance The cosmetic effect of topical compositions according to the present teachings, such as prepared in Examples 2-6, can be tested on skin of healthy human volunteers by application of the formulations to be tested to facial skin. The volunteers are free of dermatological problems, irritated skin, blemishes, or such marks on test site(s) that may impair the study. The samples may include a) a dermatological composition containing a predetermined concentration of a nanodispersion of core-shell nano-particles in a polar carrier (which can be prepared according to Example 2); b) a dermatological composition containing a predetermined concentration of a nanodispersion of core-shell nano-particles positively charged in an acidic aqueous solution of a polar carrier (which can be prepared according to Example 6); c) a dermatological composition containing a predetermined concentration of a nanodispersion of core-shell nano-particles in an acidic aqueous solution of a polar carrier, coated with a carrier-soluble active agent (which can be prepared according to Example 7, e.g.. LMW HA-ND12, Vitamin C-ND12, Collagen-ND12, or Elastin-ND12, as well as core-shell nano-particles coated with HMW HA); d) a placebo composition comprising the polar carrier of sample a) or the acidic solution of the polar carrier of samples b)-c), but no core-shell(s) nano-particles. The clinical study is conducted in a double-blind manner, at least ten volunteers being randomly assigned to each arm of the study (i.e., half for each one of the compositions containing the core-shell(s) nano-particles, and the second half for each one of the respective placebo compositions), the concentration of the nano-particles being the same in the nonplacebo groups. All groups apply 1 ml of their respective compositions twice-daily (morning and evening) by gently rubbing on facial skin. Facial skin parameters Wrinkle counts: The effect of the various compositions on facial skin’s wrinkles can be determined using Caulfield’s VISIA system (by Canfield Scientific, USA), consisting of the VISIA imaging booth and VISIA software, for capturing and storing facial images using standard lighting, cross-polarized flash, and UV flash. Measurements are taken from the targeted areas before the first application (baseline), after one (Ti), two (Ti) and three (T3) months of twice-daily applications of the dermatological compositions being tested. The results of the Ti, T2 and T3 time-points are compared to the baseline values initially obtained for each volunteer, as well as to the results of the placebo arm at same timepoints. The software automatically isolates or “masks” specific areas of the face, as captured in the images, and then performs an extensive analysis of these areas to evaluate skin features such as wrinkles. The data provided by the VISIA system is displayed as “Feature Counts”, which provides a count of the number of discrete instances of the feature being evaluated (e.g., wrinkles and lines), regardless of the size or intensity of each instance. The values can be presented as the counted wrinkles on both the left and right sides of the face (“all wrinkles”), or as average values of the wrinkles counted on each of the two facial sides (“average wrinkles”). Absolute Scores: provides a comprehensive measurement of the impact that the wrinkles have on the volunteer’s complexion. Absolute Scores characterize the total size, area and intensity of the parameter. Elasticity: The effect of the compositions of the present invention on skin elasticity can be tested using Dermal Torque Meter® (DTM310) (by Dia-Stron, United Kingdom), whereby a mechanical probe exerts a predetermined torque for a predetermined length of time (“torque on”) onto the selected area of the surface of the subject’s facial skin, followed by a "torque off’ period, in which the force is rapidly released and the skin attempts to restore the distortion created by the torsional forces. The angular rotation of the torque disk is measured throughout this process and provided as the ratio of the “torque on” to “torque off’ periods. Facial skin hydration: The effect of the compositions of the present invention on skin hydration can be measured to confirm that the changes in wrinkle count and / or elasticity can indeed be attributed to a specific collagen-stimulating activity of the compositions and not to a change in hydration level of the skin surface. Skin hydration analysis can be performed using Corneometer* CM 825 (by Courage+Khazaka electronic GmbH, Germany), which measures the capacitance of the stratum comeum, using a probe capacitor effecting an electric scatter field penetrating the first layers of the stratum comeum (10-20 pm). The results are reported in arbitrary units. The capacitance variation due to skin surface hydration is measured before application of the composition (baseline) and compared to the values measured after one month of application, for the tested compositions as well as for the placebo being used as control. It is expected that neither the core-shell nano-particles compositions nor the control composition would significantly affect the skin hydration level. Hydration levels are also not expected to change after continued application of the present compositions, such values reaching saturation relatively rapidly and only fluctuating as a result of climatic conditions. These anticipated results would indicate that the effect of the tested compositions on reducing the number of wrinkles and / or increasing skin elasticity can be specifically attributed to the core-shell nano-elements and do not result from an effect of the liquid phase on skin properties. In vivo collagen production within facial skin: To confirm that the efficacy of the present compositions stems inter alia from the coreshell nano-elements, their ability to be transdermally delivered, and their ability to fulfil their biological role of stimulating neo-synthesis, collagen levels in facial skin can be measured before and after application of the compositions. Measurements can be made using DermaLab Combo (by Cortex Technology, Denmark), a skin analysis device whereby an ultrasound probe capable of high frequency and resolution analysis is used by passing the probe on the targeted area in the face. The output includes an image of varying colors and intensities showing inter alia spots of collagen presence, the intensity of the spots corresponding to the collagen being recorded in arbitrary unis. The assessment is performed following application of the tested compositions by volunteers according to the methodology described above, as compared to a corresponding placebo compositions. The results of the above-mentioned parameters (wrinkle counts, elasticity', facial skin hydration and in vivo collagen production within the facial skin) for all volunteers in a same group can be averaged and the results of the different groups at the different time points for each parameter can be compared. A decrease of at least 10%, at least 15%, or at least 20% in each of the above parameters for any group at a given timepoint as compared to the group having received the placebo composition at the same timepoint is deemed satisfactory. While the present invention has been illustrated with a core having a collagen-stimulating activity and prospective active agents (water-insoluble in the core and / or water-soluble in a second shell) having a cosmetic or a non-cosmetic (e.g., more therapeutic) activity for living subjects, this should not be construed as limiting the scope of the present teachings. A similar method can be used wherein the material of the core is a biodegradable polymer having no collagen-stimulating activity. Core-shell nano-elements prepared from such non-CSSC materials may be applied on any types of surfaces (not only on skin and typically on surfaces other than skin) of any living subject (e.g., humans, animals, or plants) or of inert object. The active agents, whether in the core or the shells, may provide any desirable activity and be, for illustration, a bactericide, a fertilizer, a fungicide, a pesticide, a virucide, etc. It is appreciated that certain features of the disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub combination or as suitable in any other described embodiment of the disclosure. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements. Although the present disclosure has been described with respect to various specific embodiments presented thereof for the sake of illustration only, such specifically disclosed embodiments should not be considered limiting. Many other alternatives, modifications and variations of such embodiments will occur to those skilled in the art based upon Applicant’s disclosure herein. Accordingly, it is intended to embrace all such alternatives, modifications and variations and to be bound only by the spirit and scope of the disclosure and any change which come within their meaning and range of equivalency. In the description and claims of the present disclosure, each of the verbs “comprise”, “include” and “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of features, members, steps, components, elements or parts of the subject or subjects of the verb. Yet, it is contemplated that the compositions of the present teachings also consist essentially of, or consist of, the recited components, and that the methods of the present teachings also consist essentially of, or consist of, the recited process steps. As used herein, the singular form “a”, “an” and “the” include plural references and mean “at least one” or “one or more” unless the context clearly dictates otherwise. At least one of A and B is intended to mean either A or B, and may mean, in some embodiments, A and B. A “material” that may be present in the composition alone or in combination with other materials of the same type can be referred to as “material(s)”; CSSC(s), CSSP(s), fatty amine(s), polar carrier(s), non-volatile liquid(s), surfactants), active agent(s) and the like, respectively indicating that at least one CSSC, at least one CSSP, at least one fatty amine, at least one polar carrier, at least one non-volatile liquid, at least one surfactant, at least one active agent, and so on, can be used in the present methods or be included in the composition or satisfy the recited parameter or suitable range thereof. Unless otherwise stated, the use of the expression “and / or” between the last two members of a list of options for selection indicates that a selection of one or more of the listed options is appropriate and may be made. Unless otherwise stated, when the outer bounds of a range with respect to a feature of an embodiment of the present technology are noted in the disclosure, it should be understood that in the embodiment, the possible values of the feature may include the noted outer bounds as well as values in between the noted outer bounds. As used herein, unless otherwise stated, adjectives such as “substantially”, “approximately” and “about” that modify a condition or relationship characteristic of a feature or features of an embodiment of the present technology, are to be understood to mean that the condition or characteristic is defined to within tolerances that are acceptable for operation of the embodiment for an application for which it is intended, or within variations expected from the measurement being performed and / or from the measuring instrument being used. When the term “about” and “approximately” precedes a numerical value, it is intended to indicate + / -15%, or + / -10%, or even only + / -5%, and in some instances the precise value. Furthermore, unless otherwise stated, the terms (e.g., numbers) used in this disclosure, even without such adjectives, should be construed as having tolerances which may depart from the precise meaning of the relevant term but would enable the invention or the relevant portion thereof to operate and function as described, and as understood by a person skilled in the art. While this disclosure has been described in terms of certain embodiments and generally associated methods, alterations and permutations of the embodiments and methods will be apparent to those skilled in the art. The present disclosure is to be understood as not limited by the specific embodiments described herein. Certain marks referenced herein may be common law or registered trademarks of third parties. Use of these marks is by way of example and shall not be construed as descriptive or limit the scope of this disclosure to material associated only with such marks.

Claims

1. A dermatological composition comprising core-shell nano-elements dispersed in a polar carrier, the core-shell nano-elements being composed of:a) a core comprising a water-insoluble biodegradable collagen synthesis stimulating compound (CSSC) having a molecular weight of 0.6 kDa or more; andb) a shell surrounding the core, comprising a water-insoluble fatty amine, non-covalently bonded to the CSSC;wherein the core-shell nano-particles are positively chargeable in water; andwherein at least 50% of the total number of the core-shell nano-elements have an average diameter (e.g., Dn50) of 200 nanometer (nm) or less.

2. The dermatological composition as claimed in claim I, wherein the CSSC is characterized by at least one, at least two, or at least three of the following properties:i. the CSSC is insoluble in the polar carrier;ii. the CSSC has at least one of a first melting temperature (Tm), a first softening temperature (Ts) and a first glass transition temperature (Tg) of at most 300°C, at most 250°C, at most 200°C, at most 180°C, at most 150°C, or at most I20°C;iii. the CSSC has a first Tin or Ts of at least 20°C, at least 30°C, at least 40°C, at least 50°C, or at least 60°C;iv. the CSSC has a first Tg of -75°C or more, -50°C or more, -25°C or more, 0°C or more, 25 °C or more, or 50°C or more;v. the CSSC has at least one of a first Tm, Ts and Tg between 20°C and 300°C, between 20°C and 250°C, between 20°C and 200°C, between 30°C and 180°C, between 40°C and 180°C, or between 50°C and 150°C;vi. the CSSC has a molecular weight of 0.7 kDa or more, 0.8 kDa or more, 0.9 kDa or more, 1 kDa or more, 2 kDa or more, or 5 kDa or more;vii. the CSSC has a molecular weight of 500 kDa or less, 300 kDa or less, 200 kDa or less, 100 kDa or less, 80 kDa or less, 50 kDa or less, 25 kDa or less, or 15 kDa or less; andviii. the CSSC has a molecular weight between 0.6 kDa and 500 kDa, between 0.7 kDa and 300 kDa, between 0.8 kDa and 200 kDa, between 1 kDa and 100 kDa, or between 2 kDa and 80 kDa.

3. The dermatological composition as claimed in claim 1 or claim 2, wherein the CSSC is selected from:(I) a polymer selected from a group of polymer families comprising aliphatic polyesters, polyhydroxy-alkanoates, poly(alkene dicarboxylates), polycarbonates, aliphatic-aromatic copolyesters, isomers thereof, copolymers thereof and combinations thereof; and(II) a quinone selected from a group including Coenzyme Q10.

4. The dermatological composition as claimed in any one of claim I to claim 3, wherein the core further comprises at least one of a non-volatile liquid and a water-insoluble active agent.

5. The dermatological composition as claimed in claim 4, wherein the non-volatile liquid is selected from a group comprising monofunctional or polyfunctional aliphatic esters, fatty esters, cyclic organic esters, fatty acids, terpenes, aromatic alcohols, aromatic ethers, aldehydes and combinations thereof.

6. The dermatological composition as claimed in any one of claim 1 to claim 5, wherein the CSSC has at least one of a second Tm, Tg or Ts, lower than a respective first Tm, Tg or Ts of the CSSC, at least one of the second Tm, Tg and Ts of the plasticized CSSC being in a range from 0°C to 290°C, 10°C to 250°C, from 20°C to 200°C, from 30°C to I90°C, from 40°C to 180°C, or from 50°C to 170°C.

7. The dermatological composition as claimed in any one of claim 1 to claim 6, wherein the water-insoluble fatty amine is a primary, a secondary or a tertiary Cx-20 straight, branched, cyclic, saturated or unsaturated alkyl amine or a combination thereof.

8. The dermatological composition as claimed in any one of claim I to claim 7, wherein the CSSC in a native form has a first viscosity and the CSSC in the dermatological composition has a second viscosity lower than the first viscosity, at least one of the first and second viscosities being of 10’' mPa s or less, IO6 mPa s or less, 105 mPa s or less, 104 mPa s or less, or 103 mPa-s or less, as measured at a temperature of 50°C and a shear rate of 10 sec’s.

9. The dermatological composition as claimed in any one of claim 1 to claim 8, wherein the polar carrier has a boiling temperature (Thc) between 45°C and 350°C, between 70°C and 300°C, between 85°C and 250°C, or between 90°C and 250°C, the polar carrier being optionally selected from a group consisting of water, glycols, glycerols and combinations thereof.

9. The dermatological composition as claimed in any one of claim 1 to claim 8, furthercomprising at least one surfactant being an emulsifier or an hydrotrope.

10. The dermatological composition as claimed in any one of claim I to claim 9, wherein the core-shell nano-elements have a charge of +5 mV or more, +10 mV or more, +20 mV or more, +30 mV or more, or +40 mV or more, in water.

11. The dermatological composition as claimed in any one of claim 1 to claim 10, further comprising a carrier-soluble active agent forming a second shell on the outer surface of the core-shell nano-elements.

12. The composition as claimed in any one of claim 1 to claim 11, wherein at least one of the core-shell nano-elements and the core-shell nano-elements having a second shell made of the active agent have a Dn50 of 190 nm or less, 175 nm or less, 150 nm or less, 125 nm or less, 100 nm or less, 90 or less, 80 or less, or 70 or less, and optionally of 5 nm or more.

13. A method for preparing a dermatological composition comprising core-shell nanoelements dispersed in a polar carrier, the core-shell nano-elements comprising a collagen-synthesis stimulating compound (CSSC), the method comprising the steps of:a) providing a CSSC, wherein:i. the CSSC is biodegradable;ii. the CSSC is water-insoluble;iii.the CSSC has a molecular weight of at least 0.6 kDa;iv. the CSSC has at least one of a first melting temperature (Tm), a first softening temperature (Ts), and a first glass transition temperature (Tg) of 300°C or less; andv. the CSSC has a first viscosity optionally higher than 107 mPas, as measured at 50°C and a shear rate of 10 sec'1;b) mixing the CSSC with a water-insoluble fatty amine and optionally with a non-volatile liquid miscible with the CSSC, the mixing being at a mixing temperature equal to or higher than at least one of the first Tm, Ts, and Tg of the CSSC, whereby a homogeneous mixture of an optionally plasticized CSSC and fatty amine is formed, the mixture including the CSSC having a second Tm, Ts, or Tg lower than the respective first Tm, Ts, or Tg, and a second viscosity lower than the first viscosity, at least one of the first and the second viscosity being of 107 mPas or less, as measured at 50°C and a shear rate of 10 sec'1;c) combining a polar carrier with the mixture obtained in step b); andd) nano-sizing the combination of step c) by applying shear at a shearing temperature equal to or higher than at least one of the first Tm, Ts, and Tg of the CSSC or at least one of the second Tm, Ts, and Tg of the optionally plasticized CSSC, so as to obtain a nanosuspension, whereby core-shell nano-elements of (optionally plasticized) CSSC and fatty amine are dispersed in the polar carrier, the nano-elements having an average diameter Dv50 of 200 nm or less;wherein at least 50% of the total number of the core-shell nano-elements have an average diameter (e.g., Dn50) of 200 nanometer (nm) or less.

14. The method as claimed in claim 13, wherein the CSSC is further characterized by at least one, at least two, or at least three of the following properties:i. the CSSC is insoluble in the polar carrier;ii. the CSSC has at least one of a first Tm, Ts, or Tg of at most 250°C, at most 200°C, at most 180°C, at most 150°C, or at most 120°C;iii. the CSSC has a first Tm or Ts of at least 20°C, at least 30°C, at least 40°C, at least 50°C, or at least 60°C;iv. the CSSC has a first Tg of -75°C or more, -50°C or more, -25°C or more, 0°C or more, 25°C or more, or 50°C or more;v. the CSSC has at least one of a first Tm, Ts and Tg between 20°C and 300°C, between 20°C and 250°C, between 20°C and 200°C, between 30°C and 180°C, between 40°C and 180°C, or between 50°C and 150°C;vi. the CSSC has a molecular weight of 0.7 kDa or more, 0.8 kDa or more, 0.9 kDa or more, 1 kDa or more, 2 kDa or more, or 5 kDa or more;vii. the CSSC has a molecular weight of 500 kDa or less, 300 kDa or less, 200 kDa or less, 100 kDa or less, 80 kDa or less, 50 kDa or less, 25 kDa or less, or 15 kDa or less; andviii. the CSSC has a molecular weight between 0.6 kDa and 500 kDa, between 0.7 kDa and 300 kDa, between 0.8 kDa and 200 kDa, between I kDa and 100 kDa or between 5 kDa and 80 kDa.

15. The method as claimed in claim 13 or claim 14, wherein the CSSC is mixed with the non-volatile liquid in step b), the non-volatile liquid being added at a concentration within a range of 5 wt.% to 350 wt.%, 10 wt.% to 200 wt.%, 25 wt.% to 150 wt.? / o, or 50 wt.% to 125 wt.% by weight of the CSSC.

16. The method as claimed in any one of claim 13 to claim 15, wherein the CSSC is mixed with the non-volatile liquid in step b) and at least one of the second Tm, Ts, or Tg of the plasticized CSSC is in a range from 0°C to 290°C, 10°C to 250°C, from 20°C to 200°C, from 30°C to 190°C, from 40°C to 180°C, or from 50°C to 170°C.

17. The method as claimed in any one of claim 13 to claim 16, wherein the CSSC is mixed with the non-volatile liquid in step b), and at least one of the first viscosity of the CSSC and the second viscosity of the plasticized CSSC is 5xl06 mPas or less, 106 mPas or less, 5xlO5 mPas or less, 105 mPa s or less, 104 mPa s or less, or 103 mPa s or less, as measured at 50°C and a shear rate of 10 sec'1.

18. The method as claimed in any one of claim 13 to claim 17, wherein the water-insoluble fatty amine is a primary, a secondary or a tertiary Cs-20 straight, branched, cyclic, saturated or unsaturated alkyl amine or a combination thereof.

19. The method as claimed in any one of claim 13 to claim 18, wherein step b) is included and further comprising combining during step b) at least one of:i. a polar-carrier-insoluble surfactant; andii. an intermediate emulsifier; andiii. a polar-carrier-insoluble active agent.

20. The method as claimed in any one of claim 13 to claim 19, wherein the polar liquid carrier further comprises a pH-modifying agent.

21. The method as claimed in any one of claim 13 to claim 20, wherein the core-shell nano-particles have a charge of +5 mV or more, +10 mV or more, +20 mV or more, +30 mV or more, or +40 mV or more, in water, as measured at room temperature.

22. The method as claimed in any one of claim 13 to claim 21, further comprising during or after step c) or step d), adding a polar-carrier-soluble active agent within the polar carrier, at least a part of said active agent forming a second shell on the outer surface of the core-shell nano-elements.

23. The method as claimed in any one of claim 13 to claim 22, further comprising adding during or after step c) or step d) at least one of:i. a polar-carrier-soluble surfactant;ii. an intermediate emulsifier; andiii. a skin penetration enhancer.

24. The method as claimed in any one of claim 13 to claim 23, wherein the polar carrier has a boiling temperature Tbc at a pressure of nano-sizing and the fatty amine and optional nonvolatile liquid have boiling temperatures Tba and Tbi at a pressure of mixing, and the fatty amine has a degradation point at a pressure of mixing, the temperature of nano-sizing being lower than Tbc and the temperature of mixing being lower than Tba, the fatty amine degradation point and optionally lower than Tb / .

25. Use of a dermatological composition for improving skin appearance, the dermatological composition comprising core-shell nano-elements dispersed in a polar carrier, the core-shell nano-elements being composed of:a) a core comprising a biodegradable water-insoluble collagen-synthesis stimulating compound (CSSC) having a molecular weight of 0.6 kiloDalton (kDa) or more; andb) a shell surrounding the core, comprising a water-insoluble fatty amine, non-covalently bonded to the CSSC;wherein the core-shell nano-particles are positively chargeable in water; andwherein at least 50% of the total number of the core-shell nano-elements have an average diameter (e.g., Dn50) of 200 nanometer (nm) or less.

26. The use as claimed in claim 25, wherein the dermatological composition is a dermatological composition as claimed in any one of claim 1 to claim 12.

27. The use as claimed in claim 25 or claim 26, wherein the dermatological composition is a cosmetical composition and improving skin appearance includes at least one of combating collagen breakdown, treating signs of ageing of the skin, combating wrinkles and fine lines, combating wizened skin, combating flaccid skin, combating thinned skin, combating dull, lifeless skin, and combating lack of elasticity and / or tonicity of the skin.

28. The use as claimed in claim 25 or claim 26, wherein the dermatological composition is a pharmaceutical composition and improving skin appearance includes at least one of treating skin lesions, restoring skin integrity, promoting wounds healing, alleviating local inflammation and / or local pain inflicted by skin lesions.

29. A method for cosmetically or pharmaceutically treating a skin for improving skin appearance, the method comprising applying to the skin a dermatological composition as claimed in any one of claim 1 to claim 12.

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