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EP-4192613-B1 - HYBRID CORE-SHELL MICROCAPSULES FOR ENCAPSULATING ACTIVE INGREDIENTS

EP4192613B1EP 4192613 B1EP4192613 B1EP 4192613B1EP-4192613-B1

Inventors

  • TYLKOWSKI, Bartosz
  • MONTORNÉS DAURA, Josep Maria
  • GARCIA VALLS, RICARD
  • HAPONSKA, Monika
  • MARIA COTA, Iuliana
  • MARTINEZ CHAMORRO, Denia
  • BERNAL LABRADOR, Cristobal
  • PUIGPINOS COLILLAS, Albert

Dates

Publication Date
20260506
Application Date
20210805

Claims (14)

  1. Organic-inorganic core-shell microcapsules having a particle size distribution D90 from 2 to 800 µm, defined and measured as described in the description, wherein: a) the shell of each microcapsule forms a network which comprises: i) an anionic polymer which comprises a plurality of carboxylate or sulfonate groups, ii) a cationic polymer which comprises a plurality of quaternary ammonium groups, iii) an alkali metal silicate or a silicate precursor, and iv) a coupling agent which is an organosilane comprising at least a terminal group selected from a quaternary ammonium group, hydroxy, and carboxylate, and v) a cross-linking agent which is a multivalent metallic cation, and b) the core of each microcapsule comprises one or more active ingredients in liquid form.
  2. The organic-inorganic core-shell microcapsules according to claim 1, wherein the anionic polymer is selected form the group consisting of alginate, carrageenan, gellan gum, carboxyl methyl cellulose, hyaluronic acid, and a combination thereof.
  3. The organic-inorganic core-shell microcapsules according to any of the claims 1-2, wherein the cationic polymer is selected form the group consisting of chitosan, N,O-carboxymethyl-chitosan, N,O-glycolic-chitosan, poly-L-lysine, and a combination thereof.
  4. The organic-inorganic core-shell microcapsules according to any of the claims 1-3, wherein the anionic polymer is alginate, and the cationic polymer is chitosan.
  5. The organic-inorganic core-shell microcapsules according to any of the claims 1-4, wherein the silicate precursor has the formula Si(R 1 ) m (R 2 ) n , wherein: m and n are an integer from 1 to 3 provided that n+m is 4; each R 1 is independently halogen, hydroxy or -O(C 1 -C 12 )alkyl; and each R 2 is independently selected from halogen, -(C 1 -C 12 )alkyl, vinyl, allyl, phenyl, and -O(C 1 -C 12 )alkyl; wherein -(C 1 -C 12 )alkyl, and -O(C 1 -C 12 )alkyl are unsubstituted or substituted with one or more substituents selected from the group consisting of halogen, hydroxy, glycicyl and methacryloyl.
  6. The organic-inorganic core-shell microcapsules according to any of the claims 1-5, wherein the coupling agent is an organosilane of the formula Si(R 3 ) o (R 4 ) p , wherein: o and p are an integer from 1 to 3 provided that o+p is 4; each R 3 is independently halogen, hydroxy or -O(C 1 -C 12 )alkyl; and each R 4 has independently one of the formulas below: wherein q is an integer from 1 to 5, r is an integer from 1 to 5, s is an integer from 0 to 2, Ar is unsubstituted (C 6 -C 12 )aryl or (C 6 -C 12 )aryl substituted with one or more substituents selected from the group consisting of halogen, hydroxy, -(C 1 -C 3 )alkyl, -(C 1 -C 3 )alkyl substituted with one or more halogen atoms, -O(C 1 -C 3 )alkyl, and -O(C 1 -C 3 )alkyl substituted with one or more halogen atoms, and R 5 is selected from the group consisting of -NH 3 + , -NH 2 + R 6 , hydroxy and carboxylate, and R 6 is hydrogen or -(C 1 -C 6 )alkyl.
  7. The organic-inorganic core-shell microcapsules according to any of the claims 1-6, wherein the weight amount of cationic polymer with respect to the total microcapsule shell weight is from 5 to 30%.
  8. The organic-inorganic core-shell microcapsules according to any of the claims 1-7, wherein the weight amount of anionic polymer with respect to the total microcapsule shell weight is from 5 to 45%.
  9. The organic-inorganic core-shell microcapsules according to any of the claims 1-8, wherein the weight amount of silica precursor with respect to the total microcapsule shell weight is from 5 to 40%.
  10. The organic-inorganic core-shell microcapsules according to any of the claims 1-9, wherein the weight amount of coupling agent with respect the total microcapsule shell weight is from 5 to 50%.
  11. A composition comprising the organic-inorganic core-shell microcapsules as defined in any of the claims 1-10, and one or more excipients or carriers.
  12. A process for the preparation of the organic-inorganic core-shell microcapsules as defined in any of the claims 1-10, which comprises: a) providing an aqueous solution comprising a polymer which comprises a plurality of carboxylic acid or sulfonic acid groups; an alkali metal silicate or a silicate precursor; a coupling agent which is an organosilane comprising at least a terminal group selected from amino, hydroxy, and carboxylic acid; and one or more active ingredients to obtain mixture A, wherein in solution the polymer is in anionic form comprising a plurality of carboxylate or sulfonate groups, and the terminal group of the coupling agent is in the form of a quaternary ammonium group, hydroxy, or carboxylate group; b) dissolving a polymer which comprises a plurality of amino groups in an acidic aqueous solution and adding a cross-linker to obtain solution B, wherein in solution the polymer is in cationic form comprising a plurality of quaternary ammonium groups; and c) dropping mixture A onto solution B to obtain the microcapsules.
  13. Use of the organic-inorganic core-shell microcapsules as defined in any of the claims 1-10, or alternatively of the composition as defined in claim 11 as a disinfectant.
  14. Use of the organic-inorganic core-shell microcapsules as defined in any of the claims 1-10, or alternatively of the composition as defined in claim 11 for the delivery of active ingredients.

Description

Technical Field The present invention relates to the field of chemistry, more particularly to encapsulation of active ingredients. In particular, the invention relates to hybrid inorganic-organic core-shell microcapsules, and to a process for their preparation. It also relates to compositions comprising the hybrid microcapsules, and their use as disinfectants as well as for the delivery of active ingredients. Background Art Microencapsulation technology provides material barriers (shell) between bioactive materials (core), such as essential oils, fragrance, aroma, etc. and the environment, therefore allowing improvement of their stability in final products and during processing. Recently, it became the scope of interest of numerous studies due to the wide range of possible applications for encapsulated products (i.e.: in food industry, medical sector, cosmetics, textiles). Depending on the application, microcapsules preparation methods and conditions need to be adjusted to obtain the particles with specific size, shell thickness and permeability. Biopolymers, due to their high capacity of functionalization, are promising materials for the production of the microcapsule wall. Nevertheless, recent studies put a lot of attention to the biodegradability of materials used for this purpose. The patent application CN104825421 discloses organic-inorganic double-shell microcapsules which encapsulate hydrophobic small-molecules which are prepared by 1) mixing an amphiphilic triblock copolymer, a silica precursor, a silane coupling agent, and a hydrophobic small molecule in an organic solvent; 2) dissolving the chitosan in an acid solution; and 3) adding 1) dropwise into 2). The patent application WO2017015885 discloses microcapsules containing: (i) a microcapsule core having an active material, and (ii) a microcapsule wall formed of a first polymer and second polymer. The first polymer is a sol-gel polymer. The second polymer is gum arabic, purity gum ultra, gelatin, chitosan, xanthan gum, plant gum, carboxymethyl cellulose, sodium carboxymethyl guar gum, or a combination thereof. On the other hand, alginate-based microcapsules have been reported as being used for encapsulating active ingredients. However, these capsules generally show mechanical instability and high porosity which make them unsuitable for practical applications. To overcome this problem, a polycation layer has traditionally been added to the alginate gels. However, the microcapsules obtained do not show an appropriate balance between enough mechanical stability which allows their storage until use, controlled and progressive release of the active ingredients, and biodegradability of the capsule materials. Thus, there is still a need of providing further solutions for encapsulating active ingredients which overcome the problems of the prior art. Summary of Invention The present inventors have developed new hybrid organic-inorganic core-shell microcapsules containing active ingredients (e.g. essential oils) in liquid form which show high encapsulation efficiency and excellent mechanical stability and low leakage. In particular, the inventors have found that when a coupling agent, particularly an organosilane comprising at least a quaternary ammonium group, a hydroxy group or a carboxylate group, is incorporated to the network forming the shell which comprises a cationic polymer (e.g. chitosan), and anionic polymer (e.g. alginate), and a silicate, compact microcapsules are obtained with reduced leakage of the encapsulated materials, unlike microcapsules which do not include the coupling agent. The reduced leakage increases safety to the user and non-target organisms, and also allows using reduced amounts of active ingredients. Without being bound to theory it is thought that the ability of the coupling agent to form covalent bonds with the silicate network on the one hand, and ionic bonds with the organic polymeric materials on the other hand, gives rise to an improved distribution of the inorganic structure through the shell network, which in turn results in a well-integrated and compacted shell. Furthermore, the microcapsules of the invention are able to release the encapsulated active ingredients (for example by friction or by a pH change) in a controlled and progressive way, while resulting in non-toxic and non-contaminant materials. A further advantage of the microcapsules of the invention is that different active ingredients of hydrophilic nature (i.e. water-soluble) and/or of lipophilic nature (i.e. oil-soluble) may be encapsulated in the same capsule as aqueous core material or oil in water nanoemulsion core material. Therefore, a first aspect of the invention relates to organic-inorganic core-shell microcapsules having a particle size distribution D90 from 2 to 800 µm, wherein: a) the shell of each microcapsule forms a network which comprises: i) an anionic polymer which comprises a plurality of carboxylate or sulfonate groups,ii) a cationic p