Light shields for topical use containing bismuth oxide colloid

Abstract

The present invention relates to a local composition for producing a light shield in the ultraviolet to visible radiation range comprising bismuth oxide colloid Bi2O3 in a metal-doped crystalline form.

Description

Technology Field

[0001] The present invention relates to a light shield in the UV to visible radiation range, and more specifically, to a local composition containing doped bismuth oxide colloid, particularly bismuth oxide α-Bi2O3, and optionally grafted with a polymer, and the use thereof.

[0002] The application field of the present invention is particularly in the fields of cosmetics and medical devices, more specifically in the field of protection against electromagnetic radiation. Background Technology

[0003] It is well known that ultraviolet A (UV-A; 400-315 nm) accounts for 95% of the UV rays striking the Earth's surface. This causes premature aging of the skin by generating free radicals and the resulting oxidative stress.

[0004] Ultraviolet B (UV-B; 315-280 nm) is more energetic than UV-A. However, it is partially filtered by the atmosphere and accounts for 5% of the UV rays received by the Earth. It causes actinic erythema and also helps accelerate skin aging by generating oxidative stress in cells resulting from the production of free radicals.

[0005] Ultraviolet C (UV-C; 280-100 nm) is more energetic than UV-B. On the other hand, it is almost completely filtered by the ozone layer and is not a subject of special interest in the field of solar filters.

[0006] Visible ultraviolet (UV-V; 400-490 nm) is less energetic than other ultraviolet rays. However, it is the ultraviolet ray that penetrates the deepest into the skin, reaches the reticular dermis, and potentially causes significant cell damage.

[0007] For the purposes of the present invention, the term “visible ultraviolet or UV-V” refers to visible radiation close to ultraviolet radiation, preferably 400 to 490 nm, advantageously 400 to 450 nm, and more advantageously 400 to 420 nm.

[0008] All UV rays are associated with the mechanism of cancer development.

[0009] Generally, the solar blocking composition includes at least one solar filter that may be organic or inorganic.

[0010] As a non-limiting example, organic sunscreens may be compounds belonging to the following families: aminobenzoates, cinnamates, salicylates, benzophenones, phenylbenzotriazoles, etc.

[0011] Mineral solar filters specifically contain titanium dioxide (TiO2) and zinc oxide (ZnO).

[0012] This type of protection makes it possible to limit the harmful effects of ultraviolet rays.

[0013] The various solar filters mentioned above do not cover the entire range of ultraviolet rays to which humans may be exposed. In fact, this is because filters are generally active only for a limited range of wavelengths. For example, titanium dioxide and zinc oxide do not filter out all UV-A, and organic ethylhexyl triazone filters filter out only UV-B.

[0014] More specifically, protection by filtering light against visible UV-V or ultraviolet rays, that is, visible radiation close to ultraviolet radiation, preferably 400 to 490 nm, advantageously 400 to 450 nm, and even more advantageously 400 to 420 nm, has not been the subject of effective specific development until now.

[0015] To address these issues, sunscreen compositions generally combine several sunscreens and antioxidants that neutralize the downstream effects of UV rays, namely UV-A (400 to 315 nm) and UV-V (400 to 490 nm). This may be a mixture of organic and / or mineral solar filters.

[0016] However, combining several films with numerous excipients can lead to interaction issues between different elements, affecting the efficiency of protection. On the other hand, organic filters can be easily absorbed through the skin. Furthermore, some are suspected of having harmful effects on human health, particularly as endocrine disruptors. Finally, various filters are prone to degradation, which in turn limits sun blocking or even causes harm to the body.

[0017] The problem proposed by the present invention to be solved is to develop a composition intended to protect the skin from ultraviolet radiation and that does not have the aforementioned defects.

[0018] Bismuth oxide is commonly used as an X-ray opacifier in the field of medical imaging, or in the energy field, for example, as an electrolyte in fuel cells.

[0019] The applicant recognized that the non-amorphous form of bismuth oxide, that is, the crystalline form, can be used in cosmetic compositions, particularly as an ultraviolet radiation filter, entirely unexpectedly.

[0020] According to the first aspect, the present invention relates to a local composition comprising bismuth oxide colloid Bi2O3 in a metal-doped crystalline form.

[0021] The above composition produces a light shield in the range of ultraviolet radiation to visible radiation, preferably 200 to 490 nm, advantageously 200 to 450 nm, and more advantageously 200 to 420 nm.

[0022] Due to the presence of doped bismuth oxide colloid Bi2O3 in a crystalline form, the composition provides photoprotection by blocking a significantly larger portion of electromagnetic radiation than commercially available filters. Thus, the present invention provides a clear advantage over compositions of the prior art that require the use of several organic and / or mineral filters to block the same range of wavelengths, particularly UV-C and UV-V rays.

[0023] According to the present invention, the colloid represents particles in a crystalline form. This may also be referred to as a quantum dot. In a liquid medium, for example, an aqueous medium, the colloid forms a colloidal suspension or a colloidal dispersion.

[0024] According to a preferred embodiment, the colloid exhibits a nanostructure or nanocrystal.

[0025] Bismuth oxide colloid Bi2O3 can be synthesized according to conventional techniques, for example, by a "bottom-up" approach in which a precursor grows. This synthesis route is commonly used in the field of nanomaterials and involves nucleation and growth steps from isolated atoms. This makes it possible to control the size of the colloid.

[0026] Bismuth oxide colloid Bi2O3 can be synthesized from conventional precursors such as bismuth oxalate, namely Bi2(C2O4)3 or Bi(C2O4)OH, or bismuth nitrate, Bi(NO3)3.

[0027] According to a specific embodiment, the synthesis of Bi2O3 colloid can be carried out in the presence of a basic medium, for example, sodium hydroxide.

[0028] According to another specific embodiment, the synthesis of Bi2O3 colloid can also be carried out in the presence of compounds such as nitric acid and / or polyvinylpyrrolidone and / or glycerin.

[0029] Advantageously, the synthesis of the Bi2O3 colloid according to the present invention can be carried out in water.

[0030] The Bi2O3 crystals obtained in this way can be processed by the following:

[0031] - Precipitation; and / or

[0032] - Especially washing by filtration; and / or

[0033] - Calcination.

[0034] As previously indicated, the applicant has recognized that bismuth oxide colloid can serve as a formulation for blocking electromagnetic radiation of 200 nm to 420 nm, preferably ultraviolet radiation, particularly when applied to the skin.

[0035] Crystals can be classified into crystal systems based on their morphological symmetry features and physical properties.

[0036] Bismuth oxide Bi2O3 can have different crystallographic (polymorphic) phases with different thermal, conductive, and optical properties, for example, as follows:

[0037] - α phase; and

[0038] - Tetragonal β phase;

[0039] - γ phase having a centered cubic structure;

[0040] - δ phase having a face-centered cubic structure.

[0041] The above α phase is P2 1 / cIn the space group, it crystallizes into a monoclinic type network with lattice parameters a = 5.84 Å; b = 8.15 Å; c = 7.50 Å; β = 112.97°; Z = 4. The phase exhibits ordered vacancies with quarters of free oxygen sites.

[0042] Depending on the synthesis or temperature conditions, it is possible to promote any one of the above phases.

[0043] Unexpectedly, doped bismuth oxide colloids in a monoclinic form, advantageously, or even more advantageously in an alpha-phase monoclinic form, exhibit a blocking effect over almost the entire ultraviolet range, namely wavelengths from 200 to 420 nm.

[0044] According to a specific embodiment, the composition according to the present invention comprises bismuth oxide colloid Bi2O3 existing only in a monoclinic crystalline form.

[0045] According to a specific embodiment, the composition according to the present invention comprises bismuth oxide colloid Bi2O3 existing only in an α-phase monoclinic crystalline form.

[0046] In other words, the composition according to the present invention does not contain the following bismuth oxide colloid Bi2O3:

[0047] - β, γ, and δ phases; and / or

[0048] - Tetragonal, center-cubic, and face-centered cubic forms.

[0049] According to the essential features of the present invention, bismuth oxide colloid is doped with a doping agent such as a metal.

[0050] For the purposes of the present invention, the term “doping” refers to the substitution of bismuth atoms by metal atoms within a crystal lattice.

[0051] According to the present invention, doping is performed by synthesizing bismuth oxide colloid Bi2O3 in the presence of a precursor of a doping agent or a doping agent, particularly by a "bottom-up" method.

[0052] Within the meaning of the present invention, doping is different from conventional doping, which involves first synthesizing all oxide colloids and then mixing them with a precursor of a doping agent.

[0053] According to the present invention, doping does not change the configuration of the crystal form. In other words, the X-ray powder diffraction pattern of α-Bi2O3 colloid (alpha phase and monoclinic lattice) exactly overlaps with that of α-Bi2O3 colloid (alpha phase and monoclinic lattice) doped with metal according to the present invention.

[0054] In contrast, in the prior art, doping an α-Bi2O3 colloid with an element, particularly a metal, alters its crystalline form. Subsequently, the colloid exists not only in the form of the alpha phase but also in the form of a mixture of the alpha, gamma, and / or delta phases.

[0055] According to a specific embodiment, the metal is selected from the group comprising alkali metals, alkaline earth metals, lanthanides, actinides, transition metals, poor metals, metalloids, and assemblies thereof. Advantageously, it is a transition metal.

[0056] For example, doping of bismuth oxide colloid can be carried out with iron, manganese, magnesium, copper, chromium, nickel, or even zinc, optionally with the exception of potassium or calcium.

[0057] Advantageously, the metal is iron.

[0058] Generally, the dopant is present in an amount of 0.01 to 5 mass%, more advantageously 0.01 to 0.15 mass% relative to the mass of Bi2O3 (before grafting with a biocompatible polymer).

[0059] Doping bismuth oxide colloid with a metal, preferably iron, inhibits the photocatalytic activity of the colloid. Inhibiting this activity causes the crystal mesh to separate, which prevents the transfer of electrons.

[0060] In addition to the electromagnetic radiation shielding function, doped bismuth oxide colloid can also provide antioxidant, antibacterial, bactericidal, antibiofilm, fungicidal, and antiviral properties to the cosmetic composition according to the present invention.

[0061] X-ray crystallography, also known as radiocrystallography or X-ray diffractometry, makes it possible to study the structure of crystalline materials at the atomic scale. This technique is based on the physical phenomenon of X-ray diffraction. For example, a diffractometer equipped with a copper source can be used.

[0062] Therefore, the diffraction pattern forms a true signature of the crystalline form of the compound. This signature is specific to the crystalline form of the compound. It takes the form of a list of positional peaks at each 2θ (2-theta).

[0063] According to a preferred embodiment of the present invention, the doped bismuth oxide colloid is advantageously in a monoclinic form, and more advantageously in a monoclinic form on alpha, alpha-Bi2O3, or -α-Bi2O3.

[0064] In a specific embodiment, the doped Bi2O3 colloid is grafted onto a biocompatible polymer.

[0065] The bismuth oxide colloid used in the present invention is not similar to particles of the prior art, for example, those disclosed in the literature of JP 2010-090001 and JP 2010-090002. The said literature discloses particles that are not doped or / or grafted, and their crystalline phases (α, β, γ, etc.) are not incidentally specified.

[0066] For the purposes of the present invention, the term “biocompatible” refers to a compound that is cytocompatible with skin, mucous membranes and integument and exhibits cytotoxicity of 15% or less, preferably 10% or less, to human epidermis reconstructed in vitro (SkinEthic RHE model). In other words, the compound remains nearly neutral with respect to cell viability.

[0067] The above cell compatibility can be evaluated by a cell viability test, and the reagent is the tetrazolium salt MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide).

[0068] The above MTT test is a colorimetric method for detecting mitochondrial activity and evaluating the cytotoxicity of a component. This is based on the reduction of the tetrazolium ring contained in the reagent to formazan by mitochondrial succinate dehydrogenase of living active cells. This forms a purple precipitate in the mitochondria.

[0069] In fact, after applying the test element to the epidermis for 42 minutes and then post-treatment incubation for 42 hours, cell viability is evaluated by measuring the activity of mitochondrial succinate dehydrogenase in living cells. The enzyme converts MTT into crystals of blue formazan. After eluting the crystals, spectrophotometric readings of optical density are performed at 550 nm. The measured absorbance is proportional to the number of living cells.

[0070] Biocompatible polymers can have hydrophilic or lipophilic properties. Advantageously, this is a hydrophilic polymer.

[0071] The biocompatible polymer may advantageously be hydrophilic and is selected from the group comprising polyvinylpyrrolidone (PVP) and its copolymers, such as triacontanyl-PVP, PVP-eicosen or PVP-vinyl acetate, polyvinyl acetate, polyvinyl alcohol, polyvinyl chloride, styrenics, polyamides, acrylates, polyesters, polybutene, polysaccharides, such as pullulan, arabinoxylan, cellulose, chitin, chitosan, xanthan gum, dextran, wellan gum, gellan gum, arabic gum, hyaluronic acid, cellulose and its derivatives, starch, diutan, proteins and their components, such as sericin and amino acids, fatty acids, phospholipids, phosphoglycerides, triglycerides, silane coupling agents and mixtures thereof.

[0072] Grafting prevents Bi2O3 colloid from penetrating the skin by improving bioadhesion between the colloid and the skin. In other words, improving the adhesion of the colloid to the skin limits or prevents its penetration into the skin.

[0073] Through physical or mechanical interactions and chemical interactions, the biocompatible polymer acts as a bioadhesive to the skin. Therefore, the composition according to the present invention adheres to the skin and is not removed by simple washing with water or seawater.

[0074] The bioadhesion of biocompatible polymers, occurring by forming a chemical bond with the skin, successfully induces the following:

[0075] - Close contact between the biocompatible polymer and the skin. This close contact is facilitated by the wetting and / or swelling of the bioadhesive biocompatible polymer to the skin; and

[0076] - Filling of cracks and fine wrinkles using bioadhesive biocompatible polymers.

[0077] The biocompatible polymer also improves the dispersion of the Bi2O3 colloid in an aqueous medium, and thus makes it possible to obtain a homogeneous distribution when the composition according to the present invention is applied to the skin. Accordingly, the composition containing the colloid according to the present invention is advantageously a composition in which the colloid is in a suspension.

[0078] Grafting with biocompatible polymers also makes it possible to improve the stability of Bi2O3 colloids over time and / or at acidic pH, particularly the pH of the skin from 5.2 to 7. Without grafting, Bi2O3 colloids, particularly alpha-Bi2O3, become unstable over time or / or deteriorate more rapidly at a pH of 7 or lower.

[0079] The grafting, or functionalization, of colloids is part of the general knowledge of those skilled in the art. Grafting, or functionalization, refers to the formation of covalent bonds between a biocompatible polymer and the surface of a colloid. This is not a heart / shell type colloid.

[0080] Biocompatible polymers can provide lipophilic or hydrophilic properties to colloids.

[0081] Generally, the composition may comprise a doped Bi2O3 colloid, which is advantageously grafted in an amount of 1 to 60 mass%, more advantageously 20 to 50 mass%, relative to the mass of the composition. This is the mass percentage of the doped, advantageously grafted Bi2O3 colloid.

[0082] Advantageously, the doped Bi2O3 colloid of the composition may comprise 60 to 100%, advantageously 80 to 100%, preferably 100%, of doped bismuth oxide colloid in an alpha-crystalline form, preferably in a doped monoclinic alpha-crystalline form. The doped colloid in the alpha-crystalline form is advantageously grafted onto a biocompatible polymer. In other words, according to the above embodiment, 60 to 100%, preferably 80 to 100%, more preferably 100%, of the doped Bi2O3 colloid of the composition is in an alpha-crystalline form.

[0083] The above Bi2O3 colloid is advantageously spherical in shape.

[0084] Bi2O3 colloids, whether doped and grafted or ungrafted, which are advantageously alpha-crystalline phases and preferably monoclinic alpha-crystalline phases, have a size of approximately 0.5 to 1,000 nm, more advantageously 0.5 to 100 nm, and even more advantageously about 30 nm.

[0085] The above size is measured by XRD (X-ray diffraction), a technique for measuring the size of crystals in a solid state.

[0086] The term "size" refers to the largest dimension of the colloid, for example, the diameter in the case of a spherical colloid. This is the average size of the grafted or ungrafted colloid. In fact, the size of the grafted colloid according to the present invention also falls within the range of values ​​described above.

[0087] According to a specific embodiment, the composition may also include a lipophilic and / or hydrophilic mineral sunscreen. The filter may be selected particularly from the group comprising titanium oxide (TiO2), zinc oxide (ZnO), iron oxide (Fe2O3), zirconium oxide (ZrO2), silicon oxide (SiO2), manganese oxide (e.g., MnO), aluminum oxide (Al2O3), cerium oxide (Ce2O3), and mixtures thereof.

[0088] Advantageously, the mineral sunscreen is in the form of a colloid or particle.

[0089] According to another specific embodiment, the composition may also include a lipophilic and / or hydrophilic organic sunscreen. The above filter may be selected particularly from the group including the following INCI names: camphor benzalkonium methosulfate, homosalate, butyl methoxydibenzoylmethane, phenylbenzimidazole-sulfonic acid, terephthalylidene dicamphorsulfonic acid, butyl methoxydibenzoylmethane, benzylidene camphorsulfonic acid, octocrylene, polyacrylamidomethyl benzylidene camphor, ethylhexyl methoxycinnamate, PEG-25 PABA, isoamyl p-methoxycinnamate, ethylhexyl triazone, drometrizole trisiloxane, diethylhexyl butamidotriazone, 4-methylbenzylidene camphor, 3-benzylidene camphor, ethylhexyl salicylate, ethylhexyl dimethyl PABA or octyl dimethyl PABA, benzophenone-4 / benzophenone-5, methylene Bis-benzotriazolyl tetramethylbutylphenol, disodium phenyl dibenzimidazole tetrasulfonate, bis-ethylhexyloxyphenol methoxyphenyl triazine, polysilicon-15, diethylamino hydroxybenzoyl hexyl benzoate and mixtures thereof.

[0090] According to a specific embodiment, the topical composition is intended for use in treatment.

[0091] According to another specific embodiment, the topical composition is not intended for use in treatment.

[0092] Advantageously, the composition according to the present invention is a sunscreen composition.

[0093] This may be in the form of an oil-phase or water-in-oil or oil-in-water type emulsion containing preferably a metal-doped and advantageously grafted colloid, preferably an aqueous suspension of a metal-doped and advantageously grafted colloid, and preferably a suspension of a metal-doped and advantageously grafted colloid.

[0094] The above biocompatible polymer may have hydrophilic or lipophilic properties.

[0095] When the above composition includes an oil-type dispersant, the biocompatible polymer grafted onto the bismuth oxide colloid is advantageously lipophilic.

[0096] When the above composition includes a water-type dispersant, the biocompatible polymer grafted onto the bismuth oxide colloid is advantageously hydrophilic.

[0097] The composition according to the present invention comprises, advantageously, 2 to 20 mass%, more advantageously 4 to 10 mass%, of a biocompatible polymer based on the mass of the composition. The percentage preferably comprises a biocompatible polymer selectively grafted onto a metal-doped Bi2O3 colloid.

[0098] According to a specific embodiment, the composition according to the present invention may further include at least one additive selected from the group comprising dispersants, wetting agents, stabilizers, and pH adjusters.

[0099] Advantageously, the dispersant is water and / or oil.

[0100] Preferably, the oil is selected from the group comprising hydrocarbon oils of plant origin (sunflower, corn, soybean, grapeseed, sesame, hazelnut, castor oil, etc.), hydrocarbons of mineral or synthetic origin (linear or branched) (paraffin oil, etc.), silicone oils (polymethylsiloxane, cyclopolydimethylsiloxane, etc.), fluorinated oils, and mixtures thereof.

[0101] According to another embodiment, the oil may be a hydrocarbon oil of animal origin.

[0102] The above dispersant is advantageously water.

[0103] In fact, the composition according to the present invention comprises water and / or oil in an amount of 20 to 80 mass%, more advantageously 40 to 60 mass%, relative to the mass of the composition.

[0104] Advantageously, the wetting agent is selected from the group comprising glycerol, urea, lactic acid and mixtures thereof.

[0105] The composition according to the present invention comprises, advantageously, 5 to 25 mass%, or advantageously 7 to 15 mass%, of a wetting agent based on the mass of the composition.

[0106] The above humectant helps prevent the composition from drying out too quickly after application to the skin. It also helps moisturize the skin. It can also contribute to controlling the viscosity of the composition according to the present invention for the purpose of optimizing spread on the skin.

[0107] Advantageously, the stabilizer is selected from the group comprising sorbitan monolaurate, guar gum, xanthan gum, and mixtures thereof.

[0108] The composition according to the present invention advantageously comprises 0.5 to 5 mass%, more advantageously 1 to 3 mass% of a stabilizer based on the mass of the composition.

[0109] The above stabilizer enables control of the viscosity of the composition.

[0110] Advantageously, the pH adjuster is selected from the group comprising citric acid, acetic acid, adipic acid, ascorbic acid, boric acid, fumaric acid, glycolic acid, lactic acid, malic acid, uric acid and mixtures thereof.

[0111] The composition according to the present invention comprises, advantageously, 0.1 to 1 mass%, and more advantageously 0.2 to 0.5 mass% of a pH adjuster based on the mass of the composition.

[0112] The above pH adjuster makes it possible to maintain the pH of the composition at a physiological value. This improves the stability of the composition by adjusting the pH when applied to the skin, that is, when applied to an acidic medium.

[0113] A person skilled in the art will know how to adjust the amount of pH adjuster so that the above composition advantageously has a pH of 5.2 to 7.

[0114] According to a specific embodiment, the composition according to the present invention is advantageously free of preservatives, unlike most conventional sunscreen compositions.

[0115] As previously mentioned, the above cosmetic composition is a topical composition. This has many advantages, such as the following:

[0116] - Advantageously, a simple formulation containing a small number of components in an aqueous medium,

[0117] - With increased efficiency in protection against broad-spectrum ultraviolet radiation (UV-C, UV-B, UV-A, and UV-V), this composition is preferred for solar paint,

[0118] - Very high sun protection index,

[0119] - It penetrates little to no into the stratum corneum (the outermost layer of skin cells), and thus protects sensitive and atopic skin.

[0120] - Good adhesion to the skin, allowing for long-term sun protection.

[0121] According to a preferred embodiment, the composition according to the present invention comprises the following based on mass relative to the mass of the composition:

[0122] - Advantageously, a monoclinic alpha form, α-Bi2O3, and advantageously 1 to 60% doped bismuth oxide colloid grafted with a biocompatible polymer;

[0123] - 2 to 20% of a structured biocompatible polymer, preferably polyvinylpyrrolidone (PVP);

[0124] - 5 to 25% of a wetting agent, preferably glycerol;

[0125] - 0.5 to 5% of a stabilizer, preferably sorbitan monolaurate;

[0126] - 0.1 to 1% of a pH adjuster, preferably citric acid; and

[0127] - 20 to 80% water and / or oil.

[0128] According to a preferred embodiment, the composition according to the present invention comprises the following based on mass relative to the mass of the composition:

[0129] - Advantageously existing only as the monoclinic alpha form, α-Bi2O3, and advantageously 1 to 60% doped bismuth oxide colloid grafted with a biocompatible polymer;

[0130] - 2 to 20% of a structured biocompatible polymer, preferably polyvinylpyrrolidone (PVP);

[0131] - 5 to 25% of a wetting agent, preferably glycerol;

[0132] - 0.5 to 5% of a stabilizer, preferably sorbitan monolaurate;

[0133] - 0.1 to 1% of a pH adjuster, preferably citric acid; and

[0134] - 20 to 80% water and / or oil.

[0135] Advantageously, the composition according to the present invention can be stored in a medium free of carbon dioxide, or advantageously free of oxygen. Such storage conditions make it possible to extend the shelf life of the composition according to the present invention.

[0136] The present invention also relates to the use of doped bismuth oxide colloid Bi2O3 grafted with a biocompatible polymer, advantageously as an ultraviolet filter for UV-A, UV-B, UV-C, and UV-V, preferably with a wavelength spectrum of 200-420 nm. Such use is particularly suitable when said colloid is contained in a topical cosmetic composition.

[0137] The present invention and the advantages derived therefrom will become more clearly apparent from the following drawings and embodiments, which are provided to illustrate and not to limit the invention. Brief explanation of the drawing

[0138] Figure 1 shows the absorption spectrum of an organic and mineral solar filter according to a preferred embodiment of the present invention (doped α-Bi2O3). Figure 2 shows the reflectance of colloidal solutions of doped TiO2, ZnO, and α-Bi2O3 based on wavelength. Figure 3 shows the solar protection factor (SPF) of a composition containing grafted particles of doped TiO2, ZnO, and α-Bi2O3 based on its mass%. Figure 4 shows an analysis of the photocatalytic activity of mineral sunscreen according to a preferred embodiment of the present invention (doped α-Bi2O3) and a control. Figure 5 shows an X-ray powder diffraction diagram comparing the peaks of an α-Bi2O3 colloid (monoclinic alpha crystal phase) according to the present invention and a commercially available α-Bi2O3 colloid. Specific details for implementing the invention

[0139] 1 / Synthesis of doped bismuth oxide colloid

[0140] Bismuth oxide precursors such as bismuth nitrate pentahydrate and iron precursors such as iron chloride are mixed with water, nitric acid, and sodium hydroxide, and then sealed in an autoclave.

[0141] Afterward, the reaction mixture is precipitated and then washed by filtration before undergoing a calcination step at a temperature of 100 to 500°C.

[0142] When the reaction mixture reaches the set temperature, the temperature is maintained until the doped bismuth oxide crystallizes.

[0143] Collect spherical bismuth oxide nanocrystals with a diameter of 7 nm.

[0144] According to the present invention, the X-ray powder diffraction pattern comparing the peaks of Bi2O3 colloid (α-Bi2O3) existing only in the alpha-phase crystalline form with a monoclinic lattice and a commercially available α-Bi2O3 colloid is shown in FIG. 5.

[0145] The above results show that, compared to the colloid according to the present invention, commercially available α-Bi2O3 colloids have additional and / or different peaks. Commercially available α-Bi2O3 colloids are a mixture of bismuth oxide in the alpha and gamma phases. In fact, the peak at about 30° 2θ is compatible with the gamma phase rather than the alpha phase, and a fine peak at about 27.5° 2θ near the main peak is not expected in the gamma phase but is found in the alpha phase.

[0146] In contrast, the colloid according to the present invention is pure and does not exhibit additional peaks that may be attributed to the crystalline phase of bismuth oxide other than the alpha phase. In other words, the colloid according to the present invention corresponds only to the crystalline form of the alpha phase, which is a monoclinic arrangement.

[0147] 2 / α-Bi 2 O 3 , TiO 2 and ZnO colloid

[0148] The absorption spectra of monoclinic α-Bi2O3 colloid, TiO2 particles, and ZnO particles were compared.

[0149] To this end, the following compounds were used in water:

[0150] (a) TiO2 colloid in the form of an anatase (40 nm with aggregates of about 250 nm as measured by DLS), said TiO2 grafted with 2%m PVP,

[0151] (b) ZnO colloid (15 nm) grafted with 2% m PVP,

[0152] (c) α-Bi2O3 colloid grafted with 2% m PVP and doped with iron (alpha-phase form and monoclinic arrangement colloid; 30 nm by XRD and 40 nm by DLS).

[0153] %m represents the percentage of the mass of PVP relative to the mass of α-Bi2O3 doped with TiO2, ZnO, or iron.

[0154] Grafting of the colloid is carried out in a conventional manner, for example, in a solution of water and ethanol containing the colloid and the polymer to be grafted (PVP).

[0155] The wavelength generated by the diffractometer used to measure size by XRD is Cu-K αThe line corresponds to 1.54 Å. Other parameters used are as follows: acceleration voltage: 40 kV; current: 40 mA; Bragg-Brentano geometry.

[0156] The conditions for size measurement by DLS are as follows: wavelength = 633 nm; 90° detector; 25°C. The analyzed sample is diluted with cocosilicone oil (0.5 g / L) in a 1 mm tank.

[0157] 2-a) Mass absorption coefficient

[0158] The wavelength-based average mass extinction coefficient (ε) of the above compound was obtained from measurements performed using a conventional spectrophotometer. The average mass coefficient corresponds to the average of measurements performed in tanks with thicknesses of 10 µm, 100 µm, and 0.1 cm for solutions of 10% m (100 g / L), 0.75% m (7.5 g / L), and 0.05% m (0.5 g / L), respectively. The mass coefficient is obtained from the Beer-Lambert equation:

[0159] ε = A / 1C

[0160] In the above, A is the measured absorbance, l (cm) is the optical path through the sample, and C (g / L) is the mass concentration of the sample.

[0161] The result is shown in Figure 2.

[0162] TiO2 particles exhibit a higher average mass factor in the UV-B region (280–315 nm). However, doped α-Bi2O3 colloids (alpha phase and monoclinic arrangement) exhibit significantly greater UV-A (315–400 nm) absorption performance than TiO2. The average mass factor of ZnO remains low regardless of wavelength.

[0163] 2-b) Protection against ultraviolet rays

[0164] For a 10 µm thick tank, the Solar Protection Factor (SPF), UV-A Protection Factor (FP-UVA), and critical wavelength of the previously mentioned solutions (a), (b), and (c) were calculated from the following equations:

[0165]

[0166]

[0167]

[0168] From the above:

[0169] E λ represents the erythematous spectrum (values ​​between 0 and 1) at wavelength λ. This is the amount of UV radiation at wavelength λ that is likely to cause erythema on the skin.

[0170] S λ represents the spectral irradiance at wavelength λ.

[0171] T λ represents the transmittance of the sample at wavelength λ.

[0172] d λ represents the integration variable.

[0173] The critical wavelength corresponds to the wavelength where the ratio R is 0.9 or greater. In other words, this is the integral of the spectral curve This is a wavelength that is 90% of the integral between 290 and 400 nm.

[0174] The critical wavelengths of the compounds TiO2, ZnO, and α-Bi2O3 are 368 nm, 362 nm, and 382 nm, respectively.

[0175] Only the above α-Bi2O3 compound makes it possible to achieve a critical wavelength greater than 370 nm.

[0176] Figure 3 shows the solar protection factor (SPF) of particles doped with iron and grafted with TiO2, ZnO and α-Bi2O3 (alpha phase and monoclinic arrangement) based on their mass percentage (0.1 to 30% m) in a 10-µm tank.

[0177] The above curves are used to determine the amount of solar filter required to achieve a specified solar protection factor (SPF). Table 1 specifies the mass percentage required to achieve an SPF of 20, 30, 50, or 100 from the data in Figure 3.

[0178] Mass percentage (%m) of mineral filters (TiO2, ZnO, iron-doped α-Bi2O3) based on Solar Protection Factor (SPF) SPF 20 SPF 30 SPF 50 SPF 100 TiO2(%m) 5.6 6.66 8.26 11.2 ZnO (%m) 14.5 17 21 31.7 Doped α-Bi2O3(%m) 7.06 8.04 9.3 11

[0179] Tables 2 and 3 list the UVA blocking index (SP-UVA) and SPF:SP-UVA ratio for SPFs of 50 and 100.

[0180] UVA Protection Factor (SP-UVA) and SPF:SP-UVA Ratio for SPF 50 SP-UVA SPF: SP-UVA TiO2(8.26%m) 5.22 9.57 ZnO(21%m) 8.34 6 Doped α-Bi2O3 (9.3%m) 21.21 2.36

[0181] UVA Protection Factor (SP-UVA) for SPF 100 and SPF:SP-UVA Ratio SP-UVA SPF: SP-UVA TiO2(11.2%m) 8.73 11.46 ZnO(31.7%m) 13.27 7.54 α-Bi2O3(11%m) 36.74 2.72

[0182] From the results in Fig. 3, it can be seen that the efficiency of the studied mineral filters is as follows: for concentrations of 0.1 to 10% m, TiO2 > Bi2O3 > ZnO; and for concentrations exceeding 10% m, Bi2O3 > TiO2 > ZnO. On the other hand, iron-doped α-Bi2O3 colloids (alpha phase and monoclinic arrangement) exhibit a larger absorption range than that of conventional mineral filters (Fig. 1). Therefore, this makes it possible to avoid relying on a mixture of organic and / or inorganic filters.

[0183] 3 / Photocatalytic activity

[0184] The photocatalytic activity of mineral UV filters is evaluated by monitoring the degradation of methylene blue in the presence of various filters or controls and UV radiation.

[0185] The mineral filter tested is an oxide. More precisely, it is ZnO and α-Bi2O3 doped according to the present invention.

[0186] Specifically, 10 µl of a 50 g / L oxide suspension in water, 4,990 µl of 1E in water -5 mol·L -1 It is added to the methylene blue solution. The control is also 4,990 µL of 1E in water. -5 mol·L -1 It is prepared by adding 10 µL of water to a methylene blue solution instead of an oxide suspension. The solution is placed in the dark for 30 minutes to achieve adsorption equilibrium of the dye on the surface of the oxide being studied.

[0187] Subsequently, the absorbance of the solution is measured between 540 nm and 710 nm, corresponding to the adsorption of methylene blue. The measurement constitutes time t = 0 min. The solution is then stirred under UV light.

[0188] Absorbance measurements are taken at 15, 30, 45, 60, 90, and 120 minutes.

[0189] The area under the curve between 540 nm and 710 nm makes it possible to measure the relative amount of methylene blue compared to the measurement at t = 0 min.

[0190] The result is shown in Figure 4.

[0191] The above results show that zinc oxide has significant photocatalytic activity with 90% decomposition of methylene blue within 30 minutes.

[0192] The control group shows about 10% degradation, which is due to the photodegradation of the dye under UV rather than the photocatalyst.

[0193] In the case of α-Bi2O3 colloids doped according to the present invention (alpha phase and monoclinic arrangement), degradation is almost zero, which indicates that there is no photocatalytic activity of the oxide. The photodegradation of the dye is also limited compared to the control group, because only 2% of methylene blue was degraded. This phenomenon is due to the fact that some of the UV radiation is absorbed and ROS is reduced by the iron-doped α-Bi2O3 colloids according to the present invention.

[0194] 4 / Cosmetic composition according to the present invention

[0195] A composition according to the present invention was prepared and compared with a commercially available solar composition (Table 4).

[0196] Analysis of the characteristics of commercially available compositions compared with the composition of the present invention composition UV filter (content) SPF Blocked UV-V Actinica Lotion abandonment 50+ 3.44% ISDIN Spot Prevent abandonment 50+ 0% Dermina Organic and mineral 50 19.81% Mineral crème bépanthene soleil minerals 50+ 16.59% Sun Bum abandonment 70+ 0% The present invention Iron-doped α-Bi2O3 (alpha phase and monoclinic arrangement) 50+ 25.93%

[0197] Generally, Table 4 shows that a composition containing an inorganic UV filter is most effective in blocking UV-V (visible UV: 400-450 nm). The composition according to the present invention has the best efficiency over the entire UV range (UV-C, UV-B, UV-A, and UV-V).

[0198] Skin penetration tests show that a composition containing an organic filter penetrates deeper into the skin than a mixture of organic and inorganic filters or a composition containing only an inorganic filter.

[0199] The best results are obtained in the case of the composition according to the present invention. It penetrates the skin much less than other compositions. As previously mentioned, this effect is certainly due to the improvement in the bioadhesion of the colloid resulting from grafting with a biocompatible polymer.

Claims

Claim 1 A local composition for producing a light shield in the ultraviolet to visible radiation range comprising bismuth oxide colloid Bi2O3 in a crystalline form, wherein the bismuth oxide colloid is doped with iron, the iron-doped bismuth oxide colloid represents more than 10 mass% relative to the mass of the composition, and the iron represents 0.01 to 0.15 mass% relative to the mass of Bi2O3. Claim 2 A composition according to claim 1, characterized in that the bismuth oxide colloid is in a monoclinic form. Claim 3 A composition according to claim 1, characterized in that the bismuth oxide colloid is α-Bi2O3 in the alpha phase monoclinic form. Claim 4 A composition according to claim 1, characterized in that the bismuth oxide colloid exists only as α-Bi2O3, which is a monoclinic alpha phase form. Claim 5 In claim 2, the monoclinic form is P2 1 / c A composition characterized by corresponding to the following mesh parameters in the space group: a = 5.84 Å; b = 8.15 Å; c = 7.50 Å; β = 112.97°; Z = 4. Claim 6 A composition according to claim 1, characterized in that the bismuth oxide colloid is grafted with a biocompatible polymer. Claim 7 A composition according to claim 1, wherein the bismuth oxide colloid is grafted with a biocompatible polymer selected from the group comprising polyvinylpyrrolidone (PVP) and its copolymer, triacontanyl-PVP, PVP-eicosen, PVP-vinyl acetate, polyvinyl acetate, polyvinyl alcohol, polyvinyl chloride, styrenics, polyamide, acrylate, polyester, polybutene, polysaccharide, pullulan, arabinoxylan, cellulose, chitin, chitosan, xanthan gum, dextran, wellan gum, gellan gum, arabic gum, hyaluronic acid, cellulose and its derivatives, starch, diotan, protein and its components, sericin and amino acids, fatty acids, phospholipids, phosphoglycerides, triglycerides, silane coupling agents and mixtures thereof. Claim 8 A composition according to claim 1, characterized by containing doped bismuth oxide colloid in an amount of more than 10 mass% to 60 mass% relative to the mass of the composition. Claim 9 A composition according to claim 1, characterized in that the doped Bi2O3 colloid comprises 60 to 100% of doped bismuth oxide colloid in an alpha crystalline form. Claim 10 A composition according to claim 1, characterized in that the doped bismuth oxide colloid has a size in the range of 0.5 nm to 1,000 nm. Claim 11 A composition according to claim 1, further comprising: - at least one lipophilic and / or hydrophilic mineral sunscreen selected from the group comprising: titanium oxide (TiO2), zinc oxide (ZnO), iron oxide (Fe2O3), zirconium oxide (ZrO2), silicon oxide (SiO2), manganese oxide (MnO), aluminum oxide (Al2O3), cerium oxide (Ce2O3), and mixtures thereof; and / or - At least one lipophilic and / or hydrophilic organic sunscreen selected from the group including the following INCI names: camphor benzalkonium methosulfate, homosalate, butyl methoxydibenzoylmethane, phenylbenzimidazole-sulfonic acid, terephthalylidene dicamphorsulfonic acid, butyl methoxydibenzoylmethane, benzylidene camphorsulfonic acid, octocrylene, polyacrylamidomethyl benzylidene camphor, ethylhexyl methoxycinnamate, PEG-25 PABA, isoamyl p-methoxycinnamate, ethylhexyl triazone, drometrizole trisiloxane, diethylhexyl butamidotriazone, 4-methylbenzylidene camphor, 3-benzylidene camphor, ethylhexyl salicylate, ethylhexyl dimethyl PABA or octyl dimethyl PABA, Benzophenone-4 / benzophenone-5, methylene bis-benzotriazolyl tetramethylbutylphenol, disodium phenyl dibenzimidazole tetrasulfonate, bis-ethylhexyloxyphenol methoxyphenyl triazine, polysilicon-15, diethylamino hydroxybenzoyl hexyl benzoate and mixtures thereof. Claim 12 A composition according to claim 1, further comprising at least one additive selected from the group comprising dispersants, wetting agents, stabilizers, and pH adjusters. Claim 13 A composition according to claim 1, characterized as being a sunscreen composition. Claim 14 The composition of claim 1, characterized by comprising, on a mass basis relative to the mass of the composition: - more than 10 mass% to 60 mass% of doped bismuth oxide colloid in the form of α-Bi2O3 in the alpha phase monoclinic crystal system form grafted with a biocompatible polymer; - 2 to 20% of biocompatible polymer; - 5 to 25% of wetting agent; - 0.5 to 5% of stabilizer; - 0.1 to 1% of pH adjuster; and - 20 to 80% of water and / or oil. Claim 15 A composition according to claim 1, characterized in that the doped Bi2O3 bismuth oxide colloid is used as an ultraviolet filter. Claim 16 A composition according to claim 1, characterized by achieving a solar blocking index SPF 100.

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