Poly (amino acid)-based capsules

Abstract

A capsule consisting of a polymeric shell surrounding a core, the core comprising an organic compound, the polymeric shell comprising a polypeptide comprising a moiety according to general formula I and a moiety according to general formula II. The organic compound may be a marine oil, a vegetable oil, an essential oil, a perfume, a flavoring, an insect repellant, a flame retardant, an active pharmaceutical ingredient, or an agrochemical. # imgabs0 #

Description

Technical Field

[0001] One object of the present invention is to provide a poly(amino acid) based capsule. Another object of the present invention is to provide a synthetic method for preparing a poly(amino acid) based capsule. Background Art

[0002] The biodegradability of polymers is a growing demand in a whole series of applications, especially those applications with the risk of polymers eventually entering the environment. Therefore, more and more bio-based methods appear in different technical fields. Encapsulation is a very promising technology for the controlled release of different chemicals (such as bioactive products or spices), for protecting hydrolysis-sensitive compounds in aqueous preparations, and for separating the reactivity in single fluid preparations. In addition, life sciences, agricultural chemicals and cosmetics are the main application fields of encapsulation, and it is inevitable that the encapsulated chemical substances are released in the environment or contacted with the biological environment. Therefore, biodegradability and biocompatibility will become the absolute requirements of all these applications.

[0003] Nanocapsules and microcapsules can be prepared using both chemical and physical methods. Encapsulation methods include complex coacervation, liposome formation, spray drying and precipitation, and polymerization methods. For technical applications, interfacial polymerization is a particularly preferred technique, Zhang Y. and Rochefort D.

[0004] This is reviewed by (Journal of Microencapsulation, 29(7), 636-649 (2012) and Salaün F. (in Encapsulation Nanotechnologies, Vikas Mittal (ed.), Chapter 5, 137-173 (Scrivener Publishing LLC (2013)).

[0005] Polymerization methods are particularly preferred because they allow the highest control in designing the capsules. More preferably, interfacial polymerization and most preferably interfacial polycondensation are used to prepare capsules for technical applications. In interfacial polymerization, polymerization occurs at the interface of oil droplets in an oil-in-water emulsion or at the interface of water droplets in a water-in-oil emulsion. In interfacial polycondensation, the two reactants meet at the interface of the emulsion droplets and react rapidly.

[0006] In general, interfacial polymerization requires the dispersion of a lipophilic phase in an aqueous continuous phase or vice versa. Typically, each phase contains at least one dissolved monomer (first shell component) that is able to react with another monomer (second shell component) dissolved in the other phase. After polymerization, a polymer is formed that is insoluble in both the aqueous and lipophilic phases. As a result, the polymer formed has a tendency to precipitate at the interface of the lipophilic and aqueous phases, thereby forming a shell around the dispersed phase, which grows after further polymerization.

[0007] Interfacial polymerization techniques known in the prior art rely on the polymerization of synthetic monomers often based on petrochemical products, resulting in shell chemicals generally selected from polyamides, polyureas, polyurethanes, polyesters, polycarbonates or combinations thereof. Aldehydes and other monomers such as condensation products of melamine or urea are also well documented in the literature. However, generally all such shell chemicals result in non-degradable or almost non-degradable polymers.

[0008] Poly(amino acids) are a class of well-known biocompatible and biodegradable polymers and are a preferred class of shell polymers for biocompatible microcapsules and nanocapsules design. However, classical interfacial polycondensation as described above is not suitable as a preparation method for preparing poly(amino acid) based capsules.

[0009] Poly(amino acids) can be prepared by polymerization of N-carboxyl-anhydride monomers (NCA) in a heterogeneous water-solvent system. Wang et al. (Journal of Biomedical Research Part

[0010] B: Applied Biomaterials, 89B(1), 45-54 (2009)) describes the preparation of glycopeptide microspheres starting from acylated chitosan as initiator for graft polymerization of NCA in a heterogeneous water-solvent mixture. The disclosed microspheres were prepared using L-leucine as amino acid. The particle size of the spheres ranged from tens to hundreds of micrometers and did not contain a specific core material.

[0011] Jacobs et al. disclose miniemulsion polymerization using NCA in a heterogeneous water-solvent mixture (J.Am.Soc., 141, 12522-12526 (2019)). The particle size is in the range of 200 nm. The particles do not contain core material. In addition, the L-cysteine ​​amino acid used exhibits secondary structural arrangements, such as β-pleated configurations, during the shell formation of the cap. These secondary structural arrangements interact negatively with the polymerization of NCA, causing particle deformation and resulting in reduced process tolerance for capsule production on an industrial scale.

[0012] It was further observed that the secondary structural arrangement of polyamino acids showed limited biodegradability.

[0013] In many approaches, amphiphilic block copolymers containing poly(amino acid) blocks are prepared separately and assembled into micelle-like capsules or transferred into capsules using coacervation-type methods. The amphiphilic block copolymers self-assemble into micelles that can accommodate the core material. Micellar-based capsules have the disadvantage of having a much weaker shell than capsules with a polymer shell. In many systems, crosslinking of the shell of the micellar system is therefore required.

[0014] WO 96 / 40279 discloses the production of microspheres via cavitation of amphiphilic polyamino acid block copolymers. Stable microspheres can only be achieved with block copolymers having a certain hydrophobic-hydrophilic balance, thus greatly limiting the number of suitable amino acid polymers.

[0015] In the literature, for example Jianxun Ding in Nanotechnology 22 (2011) 494012, different block copolymer-based micelles have been described as encapsulation technologies. Most micelle-like capsules require a liquid medium to maintain their spherical structure, such as to maintain the core material inside the micelle. Therefore, it is very difficult or impossible to separate micelles in a dry state. In contrast to capsules obtained by interfacial polymerization, micelle-like capsules have a limited range of available particle sizes, more particularly in a lower particle size range. In addition, the method of amphiphilic block copolymers allows good control of the polymer structure, but requires a detailed synthesis procedure to prepare well-defined polymers, which makes them less suitable for technical applications compared to interfacial polymerization-based technologies.

[0016] Other encapsulation techniques, such as complex coacervation, require extensive control of the operating process window, which is often very narrow, limiting the flexibility of the technique on an industrial scale.

[0017] Therefore, there remains a need for encapsulation methods for designing poly(amino acid)-based capsules whose process latitude is suitable for use in industrial environments and in which the shell of the capsules exhibits excellent biodegradability. Summary of the invention

[0018] It has now been found that a core-shell structure having a polypeptide shell comprising a moiety according to formula I can achieve the objects of the present invention.

[0019] The present invention comprises a capsule as defined in claim 1 consisting of a poly(amino acid) based polymer shell surrounding a core.

[0020] According to another aspect, the invention comprises a method for preparing the capsule of claim 1. The method is defined in claim 14.

[0021] Other features, elements, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention. Specific embodiments of the present invention are also defined in the dependent claims. DETAILED DESCRIPTION

[0022] A. Capsules

[0023] The objects of the present invention are achieved by a core-shell structure, wherein the core comprises an organic compound and the shell comprises a polypeptide comprising a moiety according to formula I and a moiety according to formula II

[0024]

[0025] in

[0026] R1 is selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkaryl, and substituted or unsubstituted aryl or heteroaryl.

[0027]

[0028] R2 is selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkaryl, and substituted or unsubstituted aryl or heteroaryl.

[0029] R3 is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkaryl, and substituted or unsubstituted aryl or heteroaryl.

[0030] R2 and R3 may represent the necessary atoms to form a 5-8 membered ring.

[0031] Preferably, the organic compound is a substantially low volatility hydrophobic organic compound.

[0032] A.1. Shell

[0033] The shell is a polymer shell comprising a polypeptide comprising a moiety according to formula I and a moiety according to formula II. Preferably, the polypeptide is obtained by oligomerization or polymerization of an N-carboxy-anhydride monomer according to general structure III and an N-carboxy-anhydride monomer according to general structure IV.

[0034]

[0035] in

[0036] R1 is selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkaryl, and substituted or unsubstituted aryl or heteroaryl.

[0037]

[0038] in

[0039] R2 is selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkaryl, and substituted or unsubstituted aryl or heteroaryl.

[0040] R3 is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkaryl, and substituted or unsubstituted aryl or heteroaryl.

[0041] R2 and R3 may represent the necessary atoms to form a 5-8 membered ring.

[0042] A.1.1. N-carboxyl-anhydride monomer according to the general structure III.

[0043] In a preferred embodiment, R1 is selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aralkyl and substituted or unsubstituted aryl, with unsubstituted alkyl, unsubstituted aralkyl and unsubstituted aryl being particularly preferred.

[0044] In a further preferred embodiment, the N-carboxy-anhydride monomer according to the general structure III is selected from glycine derivatives, alanine derivatives, leucine derivatives, phenylalanine derivatives, phenylglycine derivatives, valine derivatives, glutamic acid derivatives, aspartic acid derivatives, lysine derivatives, ornithine derivatives, histidine derivatives, methionine derivatives, cysteine ​​derivatives, arginine derivatives, tryptophan derivatives, cysteine ​​derivatives, isoleucine derivatives, tyrosine derivatives and serine derivatives.

[0045] Both D- and L-amino acid derivatives and mixtures thereof can be used as N-carboxy-anhydride monomers according to the general structure III. Preferably L-amino acid derivatives are used for improving biodegradability.

[0046] Leucine derivatives, alanine derivatives, phenylalanine derivatives, phenylglycine derivatives, valine derivatives, isoleucine derivatives and methionine derivatives are particularly preferred as N-carboxy anhydrides according to the general structure III.

[0047] Table 1 Typical N-carboxyl-anhydrides according to structure III are given in, but are not limited thereto.

[0048] Table 1

[0049]

[0050]

[0051] A.1.2. N-carboxyl-anhydride monomer according to the general structure IV.

[0052] In a preferred embodiment, R2 is selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aralkyl and substituted or unsubstituted aryl.

[0053] In another preferred embodiment, R3 is selected from substituted or unsubstituted alkyl, substituted or unsubstituted aralkyl and substituted or unsubstituted aryl.

[0054] In another preferred embodiment, R2 and R3 represent the necessary atoms to form a 5- or 6-membered ring.

[0055] Typical examples of N-carboxy-anhydrides according to the general structure IV are given below, but are not limited thereto.

[0056] Table 2

[0057]

[0058]

[0059] N-carboxyl-anhydrides (NCA) have been prepared using different synthetic methods, starting with the oldest method called the Leuchs method, starting with the chloroformate acylation of amino acids, which are then converted to the corresponding NCA via their acyl chlorides. Wessely and Katchalski have published several variants of this method, using a mixed anhydride method and a conversion using PBr3, respectively. Probably, the most well-known method is the Fuchs-Farting method, which uses phosgene to directly convert amino acids into the corresponding NCA. For safety reasons, phosgene has been replaced by diphosgene or triphosgene in later studies. In the past few years, several methods that do not contain phosgene have been disclosed. Secker et al. (Macromol.Biosci., 15, 881-891 (2015)) have reviewed this method.

[0060] A.2. Core

[0061] The core of the capsule according to the present invention contains an organic compound. Preferably, the organic compound is a substantially low volatility compound. Substantially low volatility is defined as 13 The boiling point is at least 150°C at mPas.

[0062] More preferably, the organic compound is a hydrophobic compound, meaning a compound having a hydrophobic property expressed as log K owThe octanol-water partition coefficient is at least 0.3. Without being bound by any theory, it is believed that the hydrophobic compounds in the lipophilic droplets hold the formed poly(amino acid) chains with hydrophilic properties to the outside of the droplets during interfacial polymerization, resulting in a strong and dense spherical polymer shell.

[0063] The average particle size of the capsules of the present invention is preferably 0.05 μm to 10 μm, more preferably 0.07 μm to 5 μm and most preferably 0.1 μm to 3 μm. Capsules according to the present invention having an average particle size below 1 μm are particularly preferred. Capsules having an average particle size below 1 μm are particularly useful for drug delivery and other pharmaceutical applications where the capsules must be introduced into an animal or human body.

[0064] B. Encapsulation Method

[0065] B.1. Preparation method of capsules

[0066] The capsules according to the present invention are preferably prepared using a ring-opening polymerisation method, more preferably using interfacial ring-opening polymerisation.

[0067] The interfacial polymerization method according to the present invention allows the preparation of capsules in a one-step process and in a wide range of functionalities and particle sizes, making it particularly suitable for industrial production processes, more particularly for continuous industrial processes. By simply adjusting the ratio of the monomers according to the general structure III and the general structure IV, the technology can be easily adjusted to the functionality to be encapsulated, and the physical properties can be easily adjusted for different applications without major changes in the process conditions, resulting in a robust technology with considerable latitude for industrialization.

[0068] Cheng and Deming (Top. Curr. Chem., 310, 1-26 (2012)) reviewed the ring-opening polymerization of N-carboxyl-anhydrides. Primary amines and optionally secondary amines are the most obvious initiators and are widely used to initiate ring-opening polymerization via nucleophilic initiation. Basic initiators can initiate ring-opening polymerization via an activated monomer mechanism, starting with deprotonation of NCA, followed by ring-opening polymerization. When amine initiators are used, the two mechanisms often run in parallel. Transition metal initiation is known to give better control over polymerization. The use of hexamethyldisilazane as an initiator to better control polymerization is also disclosed.

[0069] In another preferred embodiment, the ratio of N-carboxy-anhydride according to general structure III to N-carboxy-anhydride according to general structure IV is between 50:1-2:1, more preferably between 40:1-3:1 and most preferably between 25:1-5:1.

[0070] In a particularly preferred interfacial ring-opening polymerization process for preparing capsules according to the invention, N-carboxy-anhydride monomers according to the general structures III and IV and the organic compound to be encapsulated are dissolved in a substantially water-immiscible solvent and emulsified in an aqueous solution containing a polymerization initiator. After emulsification and optionally removal of the substantially water-immiscible solvent, ring-opening polymerization is initiated at the interface. After propagation, a polypeptide shell is formed at the organic-water interface, resulting in a core-shell structure, encapsulating the organic compound. The obtained polymer shell is mechanically strong and stable and allows the capsule to be separated from the liquid in which the capsule has been prepared.

[0071] If the organic compound is liquid, the dissolution in the substantially water-immiscible solvent can be omitted and the NCA can be dissolved directly in the liquid organic compound. The capsule according to the invention is particularly suitable for containing liquid organic compounds in the core. Micellar-based capsules are less suitable for encapsulating and containing liquid core materials. In fact, the shell of the micellar system is in many cases too permeable relative to the polymer shell obtained by the encapsulation method of the invention.

[0072] A particularly preferred interfacial ring-opening polymerization method comprises the following steps:

[0073] a) dissolving an N-carboxy-anhydride monomer according to the general structure III, an N-carboxy-anhydride monomer according to the general structure IV and an organic compound in a water-immiscible solvent; and

[0074] b) dissolving a polymerization initiator in an aqueous liquid; and

[0075] c) emulsifying the solution obtained in step a) into the aqueous liquid of step b); and

[0076] d) optionally evaporating the water-immiscible solvent; and

[0077] e) polymerizing N-carboxy-anhydride monomers according to the general structures III and IV.

[0078] The particle size of the capsules according to the invention is varied by changing the emulsification technique, the use of an emulsification aid and the ratio of the emulsification aid to the shell and the core during emulsification, the nature of the emulsification aid, varying the viscosity of the continuous or dispersed phase, the ratio of the continuous and dispersed phases, the nature of the core content and the nature of the shell monomers. As emulsification techniques, high shear techniques and ultrasound-based techniques are particularly preferred. The particle size of the capsules according to the invention can be adjusted by adjusting the shear in the high shear technique or by varying the power and amplitude during the sonication.

[0079] B.2. Initiator

[0080] Difunctional or polyfunctional primary or secondary amines or mixtures thereof are particularly preferred initiators for the ring-opening polymerization of NCA. The initiators are water-soluble and may be functionalized with additional hydrophilic functional groups, preferably selected from carboxylic acids or salts thereof, sulfonic acids or salts thereof, phosphonic acids or salts thereof, phosphates or salts thereof, sulfates or salts thereof, polyhydroxy-functional groups, poly(ethylene glycol), ammonium groups, sulfonium groups and phosphonium groups.

[0081] Typical initiators are given in Table 3, but are not limited thereto.

[0082] If used as a drug delivery system in humans or animals, the addition of poly(ethylene glycol) functional groups is particularly useful for imparting stealth properties to the capsules of the invention. These stealth properties are required to avoid absorption by the reticuloendothelial system and release the drug only at the desired site in a controlled manner.

[0083] Table 3

[0084]

[0085]

[0086] B.3. Cross-linking agents

[0087] In another preferred embodiment, the shell of the capsule further comprises a cross-linking agent. After biocompatibility and biodegradability, one of the most basic requirements of the capsule is stability in the medium (e.g., the human body for a drug delivery system) in which it must function or must be stored. If a system is unstable in its medium, this may result in a preliminary burst release of the payload or in a non-target area. The increase in stability leads to an increase in storage stability, and for a drug delivery system, leads to an increase in blood circulation time and an increase in bioavailability. With a cross-linking agent, the stability and mechanical resistance of the capsule shell can be changed to meet the specifications of the system in which the capsule is used. Further, the use of a cross-linking agent allows the drug release to be accurately controlled in the use of the drug delivery purpose of the capsule of the present invention.

[0088] Any cross-linking agent known to cross-link amine functional polymers can be used. Preferred cross-linking agents are selected from difunctional or polyfunctional isocyanates, difunctional or polyfunctional β-keto-esters, difunctional or polyfunctional β-keto-amides, difunctional or polyfunctional 1,3-diketones, difunctional or polyfunctional epoxides or oxetanes, difunctional or polyfunctional anhydrides, difunctional or polyfunctional N-carboxyl-anhydrides, difunctional or polyfunctional Michael acceptors such as acrylates, methacrylates, maleimides, vinyl sulfones, etc., and difunctional or polyfunctional pentabasic carbonates.

[0089] B.4. Emulsifying aids

[0090] Preferably, an additional emulsifying aid is used during the emulsification step of capsule preparation. Typical emulsifying aids are selected from polymers and surfactants. The polymer and surfactant may be co-reactive polymers or surfactants, for example functionalized with primary and secondary amines, which may act as both initiators and emulsifying aids, resulting in so-called self-dispersing capsules. The surfactant may be anionic, nonionic, cationic or zwitterionic. As stabilizing polymers, hydroxyl-functionalized polymers are particularly preferred, preferably selected from polysaccharides and poly(vinyl alcohol) or poly(vinyl alcohol) copolymers or derivatives thereof.

[0091] C. Application areas

[0092] The encapsulation technology disclosed in the present invention is particularly useful in the fields of personal care, pharmaceutical, nutritional, agrochemical and household applications, especially for controlling the release of active ingredients or protecting active ingredients from hydrolysis or oxidation. Examples are encapsulation of food ingredients, probiotics, spices and flavorings, agrochemicals, flame retardants and last but not least active pharmaceutical ingredients.

[0093] More generally, the components in the capsule core preferably have a log K ow An octanol-water partition coefficient of at least 0.3, more preferably at least 0.5 and most preferably at least 1.

[0094] The octanol-water partition coefficient is defined as follows,

[0095] K ow =C op / C w

[0096] Among them C op and C w are the concentrations of the compounds in the octanol-rich phase and the water-rich phase at 25 °C in g L -1 The concentration in units.

[0097] The encapsulation technology according to the present invention is of particular interest for encapsulating substantially non-reactive hydrophobic components such as marine oils, vegetable oils and essential oils. The technology is also of particular interest for encapsulating fragrances, flavorings and insect repellents.

[0098] The encapsulation technology according to the invention is further of particular interest for encapsulating active pharmaceutical ingredients and agrochemicals.

[0099] More particularly, the encapsulation technology can be used to encapsulate active pharmaceutical ingredients, such as anticancer drugs, vaccines, peptides, proteins, sonosensitizers, drug carriers, genes, growth factors such as recombinant bone morphogenetic protein (rhBMP-2), progesterone, procaine hydrochloride, bovine serum albumin, benzocaine, insulin, etc. The capsules of the present invention are particularly suitable for incorporation into pharmaceutical compositions for treating cancer.

[0100] The capsules of the present invention can be used to treat cancer, such as embolization therapy as disclosed in EP2891485A. When inserted into the human body, these microspheres in embolization therapy are used in liquid, but are preferably kept in a solid state for stable storage. In another aspect of the invention, the capsules of the present invention are suitable for sonodynamic therapy of metastatic disease, micrometastatic disease or for the treatment of multiple primary tumors.

[0101] For any medical treatment method described above, the capsule of the present invention will generally be provided as a pharmaceutical composition together with at least one pharmaceutically acceptable carrier or excipient. Such pharmaceutical compositions can be prepared using techniques well known in the art. The route of administration will depend on the intended use. Generally, these pharmaceutical compositions will be administered systemically, and therefore can be provided in a form suitable for parenteral administration, for example by intradermal, subcutaneous, intraperitoneal or intravenous injection.

[0102] Suitable pharmaceutical compositions include suspensions and solutions containing the capsules of the present invention together with one or more inert carriers or excipients. Suitable carriers include saline, sterile water, phosphate buffered saline and mixtures thereof. The composition may additionally include other agents, such as emulsifiers, suspending agents, dispersants, solubilizers, stabilizers, buffers, wetting agents, preservatives, etc. The pharmaceutical composition may be sterilized by conventional sterilization techniques. Solutions containing particles may be stabilized, for example, by adding agents such as viscosity modifiers, emulsifiers, solubilizers, etc.

[0103] Preferably, the pharmaceutical composition will be used in the form of an aqueous suspension or dispersion of capsules in water or saline solution (e.g., phosphate buffered saline). The particles can be provided in the form of a lyophilized powder for reconstitution at the time of use (e.g., for reconstitution in water, saline, or phosphate buffered saline).

[0104] The capsules according to the invention can be used in particular in consumer products selected from the group consisting of shampoos, conditioners, hair rinses, hair fresheners, hair styling agents or hair styling aids, hair bleach, hair dyes or coloring agents, soaps, shower gels, cosmetic preparations, all-purpose cleaners, bathroom cleaners, floor cleaners, window cleaners, toilet paper, paper towels, disposable wipes, diaper rash creams or ointments, baby powder, diapers, bibs, baby wipes, oral care products, toothpaste, mouthwash, teeth whiteners, denture adhesives, chewing gum, breath fresheners, mouth dissolving strips, chewing candies, hard candies, hand sanitizers, anti-inflammatory creams, anti-inflammatory ointments, anti-inflammatory sprays, health care devices, dental floss, toothbrushes, tampons, feminine hygiene napkins, personal care products, sunscreen lotions, sunscreen sprays, wax-based deodorants, glycerine-based deodorants, soap-based deodorants, facial lotions, body lotions, hand lotions, talcum powder, shaving creams, bath sprays The invention also includes the following: soak, exfoliating cream, foot cream, facial tissue, cleaning wipes, fabric care products, fabric softener, fabric freshener, ironing water, laundry detergent, dishwashing liquid, automatic dishwashing detergent, unit dose tablets or capsules, scent booster, drier sheet, fine fragrance, solid perfume, foundation, liquid foundation, eye shadow, lipstick or lip balm, Eau De Toilette products, deodorant, carpet deodorizer, candle, room deodorizer, disinfectant, antiperspirant, roll-on product and aerosol product.

[0105] D. Examples

[0106] D.1. Materials

[0107] Unless otherwise specified, all compounds were supplied by TCI Europe.

[0108] L-phenylalanine N-carboxy anhydride and D-phenylalanine N-carboxy anhydride can be prepared according to standard methods as disclosed by Gabashvill et al. (Journal of Physical Chemistry B, 111 (38), 11105-11110 (2007)) and Otake et al. (Angewandte Chemie, International Edition, 57 (35), 11389-11393 (2018)).

[0109] • L-Leucine N-carboxy anhydride and D-Leucine N-carboxy anhydride can be prepared according to standard methods as disclosed by Baars et al. (Organic Process Research and Development, 7(4), 509-513 (2003)).

[0110] N-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanine-N-carboxy anhydride was provided by TCI.

[0111] • Mowiol 488 is a poly(vinyl alcohol) supplied by Kuraray.

[0112] • Marlon A365 is an anionic surfactant supplied by Sasol Germany GMBH.

[0113] Tris(2-aminoethyl)amine was supplied by TCI.

[0114] • Cross-linker-1 is a trifunctional β-keto-ester according to the following structure, which can be prepared as disclosed by Speisschaert et al. (Polymer, 172, 239-246 (2019)).

[0115]

[0116] Caryofyllene is a hydrophobic organic compound and was supplied by Aldrich.

[0117] CATSURF-1 is a cationic surfactant according to the following structure, which can be prepared as disclosed in WO2018137993 (Agfa NV) as Surf-3.

[0118]

[0119] D.2. Methods

[0120] D.2.1. Particle size measurement

[0121] The particle size of the capsules was measured using a Zetasizer™ Nano-S (Malvern Instruments, Goffin Meyvis), which is based on dynamic light scattering. The capsules were dispersed in deionized water and the measurement temperature was 23°C.

[0122] D.2.2. Thin layer chromatography-mass spectrometry analysis

[0123] Thin layer chromatography (TLC) method was used to analyze the prepared N-carboxy-anhydride.

[0124] The prepared N-carboxylic anhydride sample was dissolved in ethyl acetate. Excess indoline was added and the N-carboxylic anhydride was reacted at room temperature for 30 minutes. Methanol / 0.5M NaCl 60 / 40 was used as eluent and the mixture was analyzed on a Grace Reveleris RPC18 TLC plate. Spots detected by mass spectrometry using a 254nm UV lamp were analyzed according to the following method:

[0125] TLC was performed under the conditions given above. TLC was analyzed using a CAMAG™ TLC-MS interface coupled to an AmaZon™ SL mass spectrometer (provided by Brüker Daltonics) via an Agilent™ 1100 HPLC pump. First, a blank spectrum was obtained by eluting the spots on the TLC plate where the compound was not present with a 0.01 molar solution of ammonium acetate in methanol. A second spectrum of the compound to be analyzed was obtained by eluting the spots of the compound under consideration with a 0.01 molar solution of ammonium acetate in methanol. The first spectrum was subtracted from the second spectrum to obtain the spectrum of the compound to be analyzed.

[0126] D.2.3. Enzymatic degradation

[0127] Aqueous dispersions containing 1 wt.% of comparative capsules or capsules according to the invention and 1 wt.% of protease from Bacillus licheniformis (type VII, lyophilized, 7-15 units / mg, supplied by Merck) were prepared in water. These dispersions were incubated at 40°C.

[0128] After one week, a sample of each dispersion was taken and analyzed using TLC in comparison to a 1 wt. % dispersion of each capsule that had not been incubated with the enzyme.

[0129] For TLC, Grace Reveleris RP C18 TLC plates were used. MeOH / 0.5 M NaCl was used as eluent and ninhydrin was used as detection method.

[0130] D.3. Example 1

[0131] This example illustrates that the biodegradability of the capsules according to the present invention is improved.

[0132] Preparation of (10aS)-10,10a-dihydro-5H-oxazolo[3,4-b]isoquinoline-1,3-dione (SNCA-3)

[0133] 5 g of (S)-(-)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid were added to 100 ml of tetrahydrofuran. The reaction vessel was coupled to a scrubber containing 1 N sodium hydroxide solution. 4.19 g of triphosgene was added to the reaction mixture and the reaction was stirred at room temperature for 2 hours under an inert atmosphere. (S)-(-)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid gradually dissolved. The reaction mixture was heated to 65° C. and the reaction was allowed to continue at 65° C. for 3 hours. The reaction mixture was allowed to cool to room temperature and the solvent was removed under reduced pressure. 100 ml of n-hexane was added and the mixture was sonicated to crystallize (10aS)-10,10a-dihydro-5H-oxazolo[3,4-b]isoquinoline-1,3-dione. (10aS)-10,10a-dihydro-5H-oxazolo[3,4-b]isoquinoline-1,3-dione was only partially crystallized. The crystalline portion was separated and the residue was isolated by evaporation of the solvent. The residue was redissolved in 5 ml of tetrahydrofuran. The crystallized (10aS)-10,10a-dihydro-5H-oxazolo[3,4-b]isoquinoline-1,3-dione dispersed in n-hexane was added to the dissolved residue and the mixture was stirred at room temperature for 15 minutes. The (10aS)-10,10a-dihydro-5H-oxazolo[3,4-b]isoquinoline-1,3-dione crystallized from the medium was separated by filtration and dried. 4.56 g (y: 80%) of (10aS)-10,10a-dihydro-5H-oxazolo[3,4-b]isoquinoline-1,3-dione were isolated.

[0134] (10aS)-10,10a-dihydro-5H-oxazolo[3,4-b]isoquinoline-1,3-dione was analyzed according to the TLC method described in §D.2.2. A compound with a molecular weight of 278 g / mol was almost the only compound detectable in TLC and corresponded to the following structure.

[0135]

[0136] This clearly indicated the formation of (10aS)-10,10a-dihydro-5H-oxazolo[3,4-b]isoquinoline-1,3-dione to a large extent.

[0137] Preparation of comparative capsule dispersion COMPCAP-1:

[0138] A first solution was prepared by dissolving 1.5 g of L-phenylalanine N-carboxy anhydride, 1.5 g of L-leucine N-carboxy anhydride, 0.336 g of Crosslinker-1, and 3.46 g of caryophyllene in 18 ml of ethyl acetate.

[0139] A second solution was prepared by dissolving 0.692 g Mowiol 4 88, 0.389 g Marlon A365 and 0.127 g tris(2-aminoethyl)amine in 30 ml water.

[0140] The first solution was added to the second solution using mixing with Ultra Turrax T25 (IKA) at 5000 rpm for 5 minutes while maintaining the temperature of the emulsion between 20-30° C. The ethyl acetate was removed under reduced pressure until the total dispersion weight was 30 g and polymerization was allowed to continue at room temperature for 24 hours.

[0141] The particle size distribution is 1μm-5μm.

[0142] Preparation of comparative capsule dispersion COMPCAP-2:

[0143] A first solution was prepared by dissolving 0.75 g of L-phenylalanine N-carboxy anhydride, 0.75 g of D-phenylalanine N-carboxy anhydride, 0.75 g of L-leucine N-carboxy anhydride, 0.75 g of D-leucine N-carboxy anhydride, 0.336 g of crosslinker-1 and 3.46 g of caryophyllene in 18 ml of ethyl acetate.

[0144] A second solution was prepared by dissolving 0.692 g Mowiol 4 88, 0.389 g Marlon A365 and 0.127 g tris(2-aminoethyl)amine in 30 ml water.

[0145] The first solution was added to the second solution using mixing with Ultra Turrax T25 (IKA) at 5000 rpm for 5 minutes while maintaining the temperature of the emulsion between 20-30° C. The ethyl acetate was removed under reduced pressure until the total dispersion weight was 35 g and polymerization was allowed to continue at room temperature for 24 hours.

[0146] The particle size distribution is 1μm-5μm.

[0147] Preparation of capsule dispersion INVCAP-1 of the present invention:

[0148] A first solution was prepared by dissolving 1.25 g of L-phenylalanine N-carboxy anhydride, 1.25 g of L-leucine N-carboxy anhydride, 0.221 g of N-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanine-N-carboxy anhydride, 0.294 g of crosslinker-1 and 3.126 g of caryophyllene in 18 ml of ethyl acetate.

[0149] A second solution was prepared by dissolving 0.625 g Mowiol 4 88, 0.352 g Marlon A365 and 0.111 g tris(2-aminoethyl)amine in 30 ml water.

[0150] The first solution was added to the second solution using mixing with Ultra Turrax T25 (IKA) at 5000 rpm for 5 minutes while maintaining the temperature of the emulsion between 20-30° C. The ethyl acetate was removed under reduced pressure until the total dispersion weight was 30 g and polymerization was allowed to continue at room temperature for 24 hours.

[0151] The particle size distribution is 1μm-5μm.

[0152] Preparation of capsule dispersion INVCAP-2 of the present invention

[0153] A first solution was prepared by dissolving 1.25 g of L-phenylalanine N-carboxy anhydride, 1.25 g of L-leucine N-carboxy anhydride, 0.442 g of N-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanine-N-carboxy anhydride, 0.308 g of crosslinker-1 and 3.366 g of caryophyllene in 18 ml of ethyl acetate.

[0154] A second solution was prepared by dissolving 0.673 g Mowiol 4 88, 0.379 g Marlon A365 and 0.117 g tris(2-aminoethyl)amine in 30 ml water.

[0155] The first solution was added to the second solution using mixing with Ultra Turrax T25 (IKA) at 5000 rpm for 5 minutes while maintaining the temperature of the emulsion between 20-30° C. The ethyl acetate was removed under reduced pressure until the total dispersion weight was 30 g and polymerization was allowed to continue at room temperature for 24 hours.

[0156] The particle size distribution is 1μm-5μm.

[0157] Preparation of capsule dispersion INVCAP-3 of the present invention

[0158] A first solution was prepared by dissolving 1.25 g of L-phenylalanine N-carboxy anhydride, 1.25 g of L-leucine N-carboxy anhydride, 0.885 g of N-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanine-N-carboxy anhydride, 0.336 g of crosslinker-1 and 3.848 g of caryophyllene in 18 ml of ethyl acetate.

[0159] A second solution was prepared by dissolving 0.770 g Mowiol 4 88, 0.433 g Marlon A365 and 0.127 g tris(2-aminoethyl)amine in 30 ml water.

[0160] The first solution was added to the second solution using mixing with Ultra Turrax T25 (IKA) at 5000 rpm for 5 minutes while maintaining the temperature of the emulsion between 20-30° C. The ethyl acetate was removed under reduced pressure until the total dispersion weight was 30 g and polymerization was allowed to continue at room temperature for 24 hours.

[0161] The particle size distribution is 1μm-5μm.

[0162] Preparation of capsule dispersion INVCAP-4 of the present invention

[0163] A first solution was prepared by dissolving 1.25 g of L-phenylalanine N-carboxy anhydride, 1.25 g of L-leucine N-carboxy anhydride, 0.147 g of (10aS)-10,10a-dihydro-5H-oxazolo[3,4-b]isoquinoline-1,3-dione, 0.294 g of crosslinker-1 and 3.052 g of caryophyllene in 18 ml of ethyl acetate.

[0164] A second solution was prepared by dissolving 0.610 g Mowiol 4 88, 0.344 g Marlon A365 and 0.111 g tris(2-aminoethyl)amine in 30 ml water.

[0165] The first solution was added to the second solution using Ultra Turrax T25 (IKA) mixing at 5000 rpm for 5 minutes while maintaining the temperature of the emulsion between 20-30° C. The ethyl acetate was removed under reduced pressure until the total dispersion weight was 30 g and polymerization was allowed to continue at room temperature for 24 hours.

[0166] The particle size distribution is 1μm-5μm.

[0167] Results of enzymatic degradation of capsule dispersions.

[0168] The enzymatic degradation of the comparative capsule dispersions COMPCAP-1 and COMPCAP-2 and the inventive capsules INVCAP-1 to INVCAP-4 was measured according to the method described in §D.2.3.

[0169] The TLC chromatograms of the comparative capsule dispersions COMPCAP-1 and COMPCAP-2 show hardly any additional compounds compared to the reference sample. Only a small amount of degradation products are visually visible. The TLC chromatograms of all the inventive capsule dispersions show several degradation products, among which the compound at Rf of 0.95 is very clearly present.

[0170] To demonstrate that the compound was formed by enzymatic degradation of the capsule shell, TLC analysis was coupled to mass spectrometry as described in §D.2.2.

[0171] The main degradation product identified in the chromatogram is a dipeptide consisting of one leucine and one phenylalanine unit as amino acids (Rf=0.95). This dipeptide is apparently formed by the enzymatic degradation of all the capsule shells according to the invention. The dipeptide could hardly be detected in the degradation experiments with the comparative capsule dispersions COMPCAP-1 and COMPCAP-2.

[0172] The colloid chemical stability of both the inventive and comparative capsule dispersions was evaluated using microscopic analysis. From this analysis it is clear that both comparative capsules COMPCAP-1 and COMPCAP-2 remain stable in dispersed form when incubated with the protease from Bacillus licheniformis, whereas all the inventive capsules flocculate during the incubation period. This flocculation indicates that the enzymatic activity of the inventive capsules increases due to the change in the shell chemical composition, leading to colloid chemical instability.

Claims

1. A capsule consisting of a polymer shell surrounding a core, the core comprising an organic compound, the polymer shell comprising a polypeptide comprising a moiety according to formula I and a moiety according to formula II in R1 is selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkaryl, and substituted or unsubstituted aryl or heteroaryl. R2 is selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkaryl, and substituted or unsubstituted aryl or heteroaryl. R3 is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkaryl, and substituted or unsubstituted aryl or heteroaryl. R2 and R3 may represent the necessary atoms to form a 5-8 membered ring.

2. Capsules according to claim 1, wherein the amount of the moiety according to formula II is 1 wt.% to 20 wt.% relative to the total weight of the polymer shell.

3. Capsule according to any one of the preceding claims, wherein the polymer shell is obtainable by oligomerization or polymerization of N-carboxy-anhydride monomers according to general structure III and N-carboxy-anhydride monomers according to general structure IV. in R1 is selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkaryl, and substituted or unsubstituted aryl or heteroaryl. in R2 is selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkaryl, and substituted or unsubstituted aryl or heteroaryl. R3 is selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aralkyl, substituted or unsubstituted alkaryl, and substituted or unsubstituted aryl or heteroaryl. R2 and R3 may represent the necessary atoms to form a 5-8 membered ring.

4. The capsule according to claim 3, wherein the N-carboxy-anhydride monomer according to the general structure III is selected from the group consisting of glycine derivatives, alanine derivatives, leucine derivatives, phenylalanine derivatives, phenylglycine derivatives, valine derivatives, glutamic acid derivatives, aspartic acid derivatives, lysine derivatives, ornithine derivatives, histidine derivatives, methionine derivatives, cysteine ​​derivatives, arginine derivatives, tryptophan derivatives, cysteine ​​derivatives, isoleucine derivatives, tyrosine derivatives and serine derivatives.

5. The capsule according to claim 3, wherein the ratio of the amount of N-carboxy-anhydride according to general structure III to the amount of N-carboxy-anhydride according to general structure IV is 50:1-2:

1.

6. The capsule according to any one of the preceding claims, wherein the organic compound has a value expressed as log K ow An octanol-water partition coefficient of 0.3 or more.

7. Capsules according to any one of the preceding claims, wherein the organic compound is selected from marine oils, vegetable oils, essential oils, fragrances, flavourings, insect repellents, flame retardants, active pharmaceutical ingredients and agrochemicals.

8. Capsules according to any one of the preceding claims, further having an average particle size of 0.07 μm to 5 μm, as measured by dynamic light scattering of the capsules dispersed in deionized water at 23°C.

9. Capsule according to any one of the preceding claims, wherein the polymer shell comprises a cross-linking agent.

10. Capsule according to any one of the preceding claims, wherein the polymer shell comprises dispersing groups selected from carboxylic acids or salts thereof, sulfonic acids or salts thereof, phosphates or salts thereof, phosphonic acids or salts thereof, protonated amines, protonated nitrogen-containing heteroaromatic compounds, quaternized tertiary amines, N-quaternized heteroaromatic groups, sulfonium and phosphonium.

11. The capsule according to any one of the preceding claims, wherein the organic compound is selected from anticancer drugs, vaccines, peptides, proteins and sonosensitizers.

12. A pharmaceutical composition comprising a capsule as claimed in claim 11 and a pharmaceutical carrier or excipient.

13. A consumer product comprising a capsule as defined in claim 1 to claim 10, wherein the consumer product is selected from shampoo, conditioner, rinse-off conditioner, hair freshener, hair fixative or hair styling aid, hair bleach, hair dye or colorant, soap, shower gel, cosmetic preparation, all-purpose cleaner, bathroom cleaner, floor cleaner, window cleaner, toilet paper, paper towel, disposable wipes, diaper rash cream or ointment, baby powder, diapers, bibs, baby wipes, oral care products, toothpaste, mouthwash, tooth whitener, denture adhesive, chewing gum, breath freshener, mouth dissolving strips, chewing candy, hard candy, hand sanitizer, anti-inflammatory cream, anti-inflammatory ointment, anti-inflammatory spray, health Care devices, dental floss, toothbrushes, tampons, feminine hygiene napkins, personal care products, sunscreen lotions, sunscreen sprays, wax-based deodorants, glycerine-based deodorants, soap-based deodorants, facial lotions, body lotions, hand lotions, talcum powder, shaving creams, shower gels, exfoliating creams, foot creams, facial tissues, cleaning wipes, fabric care products, fabric softeners, fabric fresheners, ironing water, laundry detergents, dishwashing liquids, automatic dishwashing detergents, unit-dose tablets or capsules, fragrance enhancers, dryer sheets, fine fragrances, solid perfumes, foundations, liquid foundations, eye shadows, lipsticks or lip balms, eau de toilette products, deodorants, carpet deodorizers, candles, room deodorizers, disinfectants, antiperspirants, roll-on products, and aerosol products.

14. A method for preparing a capsule as defined in any one of claims 1 to 11, comprising the steps of: a) dissolving an N-carboxy-anhydride monomer according to the general structure III, an N-carboxy-anhydride monomer according to the general structure IV and an organic compound in a water-immiscible solvent; and b) dissolving a polymerization initiator in an aqueous liquid; and c) emulsifying the solution obtained in step a) into the aqueous liquid of step b); and d) optionally evaporating the water-immiscible solvent; and e) polymerizing N-carboxy-anhydride monomers according to the general structures III and IV.

15. The method for preparing capsules according to claim 14, wherein the polymerization initiator is a difunctional or polyfunctional primary or secondary amine.

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