WO2014162311A1

WO2014162311A1 - Adjustable sol-gel-based capsules comprising fragrances and aromas, and uses thereof

Info

Publication number: WO2014162311A1
Application number: PCT/IL2014/050323
Authority: WO
Inventors: David Avnir; Marzia Sciortino; Mario Pagliaro; Rosaria Ciriminna
Original assignee: Yissum Research Development Company Of The Hebrew University Of Jerusalem Ltd.
Priority date: 2013-04-01
Filing date: 2014-04-01
Publication date: 2014-10-09

Abstract

The present invention provides compositions comprising fragrance-carrying sol-gel micro-capsules, particularly useful in many fields of industry. The present invention relates generally to controlling the release kinetic profiles of multiple fragrances and aromas through the encapsulation of one or more fragrant mixtures in metal oxides and semi-metal oxide-based micro-particles, and the use of the resulting solid particles in applications where specific component-selective adjustable controlled release of the fragrance or aroma actives is required, either to preserve the original sensory feeling, or to create new ones by changing the classical order of release of top notes, medium notes and bottom notes. The invention also relates to a method for formulating fragrances in water instead than in ethanol while diminishing the harmful interaction between the entrapped fragrance molecules and the skin.

Description

ADJUSTABLE SOL-GEL-BASED CAPSULES COMPRISING FRAGRANCES AND

AROMAS, AND USES THEREOF

FIELD OF THE INVENTION

[0001] The present invention relates generally to controlling the release kinetic profiles of multiple fragrances and aromas through the encapsulation of one or more fragrant mixtures in metal oxides and semi-metal oxide-based microparticles, and the use of the resulting solid particles in applications where specific component-selective adjustable controlled release of the fragrance or aroma actives is required.

BACKGROUND OF THE INVENTION [0002] Microencapsulation of aromas and fragrances is an important technology applied to control their release profiles and improve the efficiency of their use in a wide range of consumer products. Most encapsulation techniques for developing microencapsulated fragrances and aromas are adapted from existing methods developed in pharmacy, in the food industry, in agriculture and in cosmetics; and are still being optimised in terms of performance, scaling up and costs (J. J. G. van Soest, Encapsulation of Fragrances and Flavours: a Way to Control Odour and Aroma in Consumer Products, In "Flavours and Fragrances", R. G. Berger (Ed.), Springer: Berlin, 2007). Techniques employed in these industries include coacervation, liposome-entrapment, spray-drying and supercritical CO₂ encapsulation, among others.

[0003] The vast majority of fragrances and aromas consist of a complex mixture of a multitude of components, from just a few to hundreds. When a complex mixture of chemicals is entrapped in a carrier for its controlled release, the very encapsulation affects differently each and one of the components of the mixture in different way with different rates and different profiles of release. The resulting sensorial feeling of the released mixture is thus altered into a smell which is different from the original, whereas the prime aim of any encapsulation is to retain the original sensorial feeling.

[0004] This is also true for the incorporation or preservation of aromas components in foods and beverages, either upon opening the container, or upon heating and microwaving). Again, a main problem is the accurate preservation and release of the originally intended olfactory feeling. [0005] Many perfumes and aromas are composed not only of a mixture of many essential oils which differ greatly in their volatility, but also of mixtures of hydrophilic (alcohols, acids, bases) and hydrophobic components, which make the alterations of the sensorial feeling even more pronounced. [0006] The different volatilities of the essential oils in perfumes causes the phenomenon of top notes, medium notes and bottom notes, referring to the smell that is produced shortly after application (the most volatile components), the smell after, say, an hour (medium note), and the smell that sticks to the skin for several hours (bottom). This is a major problem in the perfumery industry, because it never allows expert -perfumers to put top smells at the bottom. This is a major problem in the perfumery industry, because it never allows expert -perfumers to put top smells at the bottom.

[0007] The sol-gel micro-encapsulation technology, described for example in US

Patent 6,303,149 and in US Patent 7,258,874, mentions the entrapment of fragrance and flavor in silica-based micro-particles. Similarly, US Patent Application 2010/0143422 relates to a microcapsule particle composition that is composed of a sol-gel material and is well suited for personal care and cleaning products. To date, however, neither the above mentioned patents nor research articles in the scientific literature mention the possibility to modify the matrix hydrophilic-lipophilic balance (HLB) to tune to overall fragrance of the material.

[0008] Boettcher and co-workers were the first to investigate organic liquids embedded in silica sol-gel glasses, as reported in Advanced Materials 11 (1999) 138-141. The authors investigated many different liquids in subsequent years, including trials to encapsulate different perfumes to prepare prolonged fragrant paper, textiles and other materials. The problem is that since a perfume consists normally of three different liquids with very different optimized volatility, by adsorption and sol-gel immobilization the relation of volatility is changed and therefore the original scent is changed.

[0009] US Patent 4,788,164 describes a micro-porous inorganic oxide glass monolith doped with a volatile organic component and a nonvolatile organic component for sustained release. No mention is made, however, of the sol-gel small particles or small capsules, or of controlling the release profile of the components. [0010] US Patent 7,258,874 discloses sol-gel microcapsules and methods for their preparation and use in controlled release applications. However, these methods are well suited for the entrapment of only water-soluble components in silica-based micro-particles, as it describes the preparation of ceramic particles from reverse micelle solution (water-in-oil, W/O).

[0011] The sol-gel micro-encapsulation technology from an oil-in-water (O/W) emulsion described in US Patent 6,303,149 offers large potential in the context of the perfume industry. The method affords 0.01-100 microns sol-gel core-shell hydrophilic microcapsules loaded with up to 80% w/w functional molecules, as stable aqueous suspensions for further formulation. However, the technology described in US Patent 6,303,149 does not mention the possibility to organically modify the surface of the inorganic silica shell around entrapped actives in order to alter the odor profile of fragrances and aromas. Also, US Patent 6,303, 149 does not mention the possibility to entrap different components in different matrices in order to achieve the desired release profile. [0012] As explained by S. Radin et al. in Biomaterials, 30 (2009) 850, in contrast to fast, short-term release from sol-gel granules produced by grinding and sieving, the release from silica-based microcapsules is slower and of longer duration. Furthermore, the release rate of the encapsulant molecules from silica-based microspheres, both in the case of full and hollow microspheres, is controlled by diffusion independently of particle size (0.01 -100 μπι) and it is determined by the internal microstructure of the micro-particle.

[0013] Ubiquitous toxic synthetic fragrances are posing serious threats that must be faced. Recent research by O. Bagasr, et al. Medical Hypotheses 80 (2013) 795 has shown that synthetic perfumes are highly mutagenic at femto-molar concentrations, and cause significant neuro-modulations in human neuroblastoma cells at extremely low levels of concentration. [0014] Essential oils, to the contrary, are renewable natural products showing multiple beneficial health effects. Yet, they are chemically unstable in the presence of air, light, moisture and high temperature, which explains industry's reliance on poorly biodegradable synthetic perfumes, even though their poor sustainability profile is now well documented. [0015] There remains an unmet need in the art for scented compositions and formulations, which provide a consistent smell regardless of the time passed since their application e.g. to a surface of an object. More, fragrances formulated in water still remain a desirable, and yet distant, objective of chemical research in perfumery. SUMMARY OF THE INVENTION

[0016] Compositions and methods to control the release kinetic profiles of multiple fragrances and aromas through the encapsulation of one or more fragrant mixtures in metal oxides and semi-metal oxide-based small particles are disclosed. The resulting solid particles are advantageously used in applications where specific component-selective controlled release of the fragrance or aroma actives is required, either to preserve the original sensory feeling, or to create new ones by changing the classical order of release of top notes, medium notes and bottom notes. The technology is ideally suited to stabilize and protect environmentally benign but unstable fragrances such as essential oils, thereby opening the route to the efficient utilization of essential oils in a number of applications, ranging from personal care to nutritional products. The invention also discloses a method for formulating fragrances in water instead than in ethanol while diminishing the harmful interaction between the entrapped fragrance molecules and the skin.

[0017] In one aspect, there is provided a fragrance-containing core-shell silica-based particle entrapment with up to 95% (w/w) fragrance molecules. [0018] In an alternative aspect, there is provided a fragrance-containing full-matrix silica-based particle.

[0019] In a third aspect, there is provided a fragrance-containing onion-shell type particles, such that from each of the shells a different smell comes out; or that different shells in the onion have different concentrations. [0020] In another aspect, the present invention relates to the use of the entrapped fragrance microcapsules applied in the fragrance/cosmetics industry. [0021] In another aspect, the entrapped fragrance microcapsules are applied to textiles, washing detergents, and as mood altering odors (in supermarkets, airports, shopping malls, class-rooms etc.).

[0022] In another aspect, the present invention relates to selectively control the release of the entrapped fragrances through tailored control of the properties of the organosilica shell, and in particular its hydrophobicity/hydrophilicity balance and textural properties (specifically pore volume and/or surface area).

[0023] In another aspect, the diameter size of the microcapsules is in the range of 0.01-

1000 microns, and preferably about 1 to about 100 microns in diameter. The shell thickness of the capsules can be controlled by varying the relative amount of monomer, such as MTMS (methyl trimethoxysilane), added to the oil phase which may vary from about 5 to about 80 weight percent.

[0024] In another aspect, the present invention relates to the use of the sol-gel microencapsulation technology for producing solid particles doped with different fragrance chemicals which, upon release, preserves the original sensorial feeling, because the release of different encapsulants in different micro -particles takes place at similar rate.

[0025] In another aspect, a note, which so far has been used only as "top", can be made "bottom" by sol-gel microencapsulation as the relative volatility and order of release of entrapped smells is controlled by controlling the release kinetic of the various components. [0026] In another aspect, this invention creates for perfumers the ability to create new smell-mixtures as it offers the opportunity to bring to a similar rate the release of different encapsulants, either from a mixture of particles, or from particles containing a mixture. This solves the traditional difficulty for perfumers to mix smells, because the volatility is different, and therefore the total overall smell changes with time. [0027] In another aspect, there is provided a method for the preparation of stable suspensions of sol-gel-encapsulated perfumes suspended in water, which can be used in sprays or applied directly, and which do not impart undue skin-feel. [0028] In another aspect, there is provided a method for using biodegradable fragrances with no environmental effects, such as for example musk odorants, which could not be used before because of low chemical stability during storage in the perfume.

[0029] In view of the above, the present invention provides, in one aspect, a composition comprising a plurality of fragrance-containing sol-gel micro-particles, the micro- particles comprising at least one active fragrance material, the fragrance material comprising at least one fragrant molecular component, wherein the sol-gel micro-particles release each component of the fragrance material in a predetermined release profile.

[0030] In some embodiments, the fragrance material comprises a plurality of fragrant components.

[0031] In some embodiments, at least two components of the plurality of fragrant components are released in different predetermined profiles.

[0032] In some embodiments, at least two fragrant components are comprised in different sol-gel micro-particles. [0033] In some embodiments, at least two fragrant components are comprised in the same sol-gel micro-particles.

[0034] In some embodiments, the sol-gel micro-particles are selected from the group consisting of full-matrix micro-particles, core/shell micro-particles, multi-shell micro-particles and any combination thereof. Each possibility represents a separate embodiment of the present invention.

[0035] In some embodiments, the sol-gel micro-particles are at least partly coated by a metal-oxide layer.

[0036] In some embodiments, the sol-gel micro-particles are porous full-matrix micro- particles, and wherein the at least one fragrant component is comprised in the internal cavities of the full-matrix micro-particles. [0037] In some embodiments, the porous full-matrix micro-particles have a predetermined matrix hydrophilic-lipophilic balance (HLB) level, a predetermined matrix surface area and a predetermined matrix porosity level.

[0038] In some embodiments, the sol-gel micro-particles are core/shell micro-particles, and wherein the at least one fragrant component is comprised in the core of the core/shell micro-particles.

[0039] In some embodiments, the core/shell micro-particles have a predetermined shell hydropWlic-lipophilic balance (HLB) level, a predetermined shell surface area and a predetermined shell porosity level. [0040] In some embodiments, the sol-gel micro-particles are multi-shell micro- particles, and wherein the at least one fragrant component is comprised in at least one shell of the multi-shell micro-particle.

[0041] In some embodiments, each shell of the multi-shell micro -particles has a predetermined shell hydrophilic-lipophilic balance (HLB) level, a predetermined shell surface area and a predetermined shell porosity level.

[0042] In some embodiments, the predetermined hydrophilic-lipophilic balance (HLB) level, the predetermined surface area and the predetermined porosity level regulate the release profile of the at least one fragrant component from the micro -particles.

[0043] In some embodiments, at least two fragrant components of the plurality of fragrant components have similar intrinsic volatilities.

[0044] In some embodiments, at least two fragrant components have different release profiles when comprised in the micro-particles.

[0045] In some embodiments, at least two fragrant components of the plurality of fragrant components have different intrinsic volatilities. [0046] In some embodiments, the at least two fragrant components have modified release profiles when comprised in the micro-particles. [0047] In some embodiments, the fragrant component is a natural fragrant component or a mixture thereof. Each possibility represents a separate embodiment of the present invention.

[0048] In some embodiments, the natural fragrant component is extracted from a plant or an animal. Each possibility represents a separate embodiment of the present invention.

[0049] In some embodiments, the natural fragrant component is an essential oil or a mixture thereof. Each possibility represents a separate embodiment of the present invention.

[0050] In some embodiments, the essential oil is an essential oil obtained from a natural source selected from the group consisting of lavender, eucalyptus, thyme, balm, rosemary, sage, peppermint, basil, ginger bergamot, hyacinth, jasmine, magnolia, orchids and vanilla. Each possibility represents a separate embodiment of the present invention.

[0051] In some embodiments, the fragrant component is a synthetic fragrant component or a mixture thereof. Each possibility represents a separate embodiment of the present invention. [0052] In some embodiments, the synthetic fragrant component is selected from the group consisting of 7-Methylbenzo[b][l,4]dioxepin-3-one (Calone), salicylates aldehydes and aromatic aldehydes. Each possibility represents a separate embodiment of the present invention.

[0053] In some embodiments, the fragrant component is a biodegradable chemical of low chemical stability.

[0054] In some embodiments, the sol-gel micro-capsules are prepared from a sol-gel precursor component selected from the group consisting of a metal, a semi-metal alkoxide, a metal ester, a semi-metal ester and any combination thereof. Each possibility represents a separate embodiment of the present invention. [0055] In some embodiments, the sol-gel precursor is of the general formula

M(R)n(P)m, wherein M is a metallic or semi metallic element, R is a hydrolysable substituent, n is an integer from 2 to 6, P is a non-polymerizable substituent, and m is an integer from 0 to 6. Each possibility represents a separate embodiment of the present invention.

[0056] In some embodiments, M is selected from the group consisting of Si, Al, Ti, Zn and Zr. Each possibility represents a separate embodiment of the present invention. [0057] In some embodiments, P is selected from the group consisting of alkyl and aryl group. Each possibility represents a separate embodiment of the present invention.

[0058] In some embodiments, the sol- gel precursor is selected from the group consisting of 3-aminopropyl trimethoxysilane (ATMS), tetramethyl orthosilicate (TMOS), methyl trimethoxysilane (MTMS), tetraethyl orthosilicate (TEOS) and any combination thereof. Each possibility represents a separate embodiment of the present invention.

[0059] In some embodiments, at least one of the micro-particles further comprises a fragrant component solvent, wherein the solvent modifies the overall hydrophilic -hydrophobic balance (HLB) level of the micro-capsule, or the vapor pressure of the microcapsule. Each possibility represents a separate embodiment of the present invention. [0060] In some embodiments, at least one of the micro-particles further comprises an additive.

[0061] In some embodiments, the additive is selected from the group consisting of a preservative, an emulsifier, a biocide, a sunscreen compound, a color, a pigment, an antibacterial compound, a skin-used vitamin and any combination thereof. Each possibility represents a separate embodiment of the present invention.

[0062] In some embodiments, the additive is co-entrapped with the at least one fragrant component.

[0063] In some embodiments, the composition described above is in suspension form.

[0064] In some embodiments, the composition described above is essentially devoid of alcohols. [0065] In some embodiments, the composition described above is essentially devoid of ethanol.

[0066] In some embodiments, the composition described above is in a powder form.

[0067] In some embodiments, the sol-gel micro-capsules have a diameter of about 0.1 to about 10 micrometer. In some embodiments, the sol- gel micro-capsules have a diameter of about 1 micrometer.

[0068] In some embodiments, the composition described above is semi-transparent or fully transparent when suspended in cosmetic or skin care formulations and applied to skin. Each possibility represents a separate embodiment of the present invention. [0069] In some embodiments, the micro-capsules are combined in a predetermined proportion to obtain a predetermined perception profile; release profile; order of release of at least one fragrant component; duration of release of at least one fragrant component; or strength of the initial perception of at least one fragrant component. Each possibility represents a separate embodiment of the present invention. [0070] In some embodiments, the perception profile is a time-dependent perception profile, determined by the duration of perception or the rate of release of the fragrance material from the microcapsules.

[0071] In some embodiments, the micro-capsules are combined in a predetermined proportion to retain the original scent of the fragrance material before encapsulation. [0072] In some embodiments, the composition described above is for use as an odor- producing material or as a malodor-masking agent in personal care products. Each possibility represents a separate embodiment of the present invention.

[0073] The present invention further provides, in an aspect, a textile or fabric comprising the composition described above. Each possibility represents a separate embodiment of the present invention.

[0074] The present invention further provides, in an aspect, a personal care product comprising the composition described above. [0075] In some embodiments, the personal care product described above is selected from the group consisting of soap, a detergent, a fabric softener, a lotion, a cream, a body wash, a shampoo and a deodorant. Each possibility represents a separate embodiment of the present invention. [0076] The present invention also provides, in an aspect, a method for manipulating the time-dependent release profile of a mixture of fragrant components, comprising encapsulating at least one fragrant component in sol-gel micro-capsules, wherein each one of the at least one fragrant components is encapsulated in micro-capsules having a predetermined hydropWlic-lipophilic balance (HLB) level, a predetermined surface area and a predetermined porosity.

[0077] The present invention also provides, in an aspect, a method for retaining the odor of a mixture of fragrant components, comprising encapsulating each fragrant component separately in sol-gel micro-capsule of similar structure, and mixing the micro-capsules.

[0078] The present invention also provides, in an aspect, a method for preventing skin side-effects related to ethanol-based perfumes, comprising encapsulating at least one fragrant component in sol-gel hydrophilic micro-capsules substantially devoid of ethanol.

[0079] The present invention also provides, in an aspect, a method for protecting and stabilizing a biodegradable fragrant component, comprising entrapping the biodegradable fragrant component within the sol-gel micro-particles composition described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 is a scanning electron microscope (SEM) image of a sample of partly aggregated 10% methyl-modified silica micro-particles co-doped with 2 fragrances.

[0081] Figure 2 is a SEM image of a sample of 10% methyl- modified silica micro- particles co-doped with 2 fragrances. [0082] Figure 3 is a SEM image of a sample of 100% methyl-modified silica micro- particles co-doped with 2 fragrances. [0083] Figures 4A and 4B are bar graphs depicating the amount of encapsulant

Geraniol and Citronellal released in ethyl acetate in consecutive extraction runs, i (a.u.) = area chromatogram/1000.

[0084] Figures 5A and 5B are SEM images of a sample of 100% TEOS micro- particles doped with bergamot oil.

[0085] Figures 6 A and 6B are pie graphs depicating the desorption profile of free bergamot oil (A) and bergamot oil encapsulated in 100% TEOS micro-particles (B).

DETAILED DESCRIPTION OF THE INVENTION

[0086] At present, one of the pivotal drawback of commercial scented consumer products is the thus far unavoidable phenomenon of top notes, medium notes and bottom notes, referring to the smell that is produced shortly after application (top notes), the smell after an hour or so (medium notes), and the smell that sticks to the scented surface for several hours post application (bottom notes). This phenomenon is caused by each smell being essentially a mixture of fragrances, each fragrance being composed of several to hundreds of volatile compounds, wherein each compound has its own volatility profile, absurdly making the perceived smell of a certain perfume to be rather time-dependent, i.e. dependent on the time passed from the perfume's application.

[0087] The carrier microcapsules of the present invention solve this problem, as the relative volatility and order of release of smells is controlled by the components of their matrices, and by the release of different encapsulants, either from a mixture of particles, or from particles containing a mixture, as further explained below. Thus, the ability to release top notes and bottom notes at a similar rate or at reversed rates, creates for performers the ability, for the first time, to create new smell-mixtures. In light of the consistent demand in the perfume industry to produce new smells, new "feels" and new order of notes, the encapsulation method described here is a non-trivial and a major step forwards in providing an efficient tool for that goal.

[0088] Another consequence of the approach described in this application is the possibility to avoid the toxic effects of fragrances formulated either in ethanol or in water. All commercially available perfumes are actually perfume oils with ethanol used as filler and sometime water. The primary purpose of ethanol is to cause the perfume oils to evaporate faster than they would by themselves, sometimes as much as 15 times more quickly. The overall consequences are that the perfume is perceived considerably stronger than it actually is, while the scent fades dramatically within 1 or 2 hours as the perfume oils evaporate along with the alcohol. Fragrance molecules can easily penetrate the skin into sub-cutaneous layers, and in fact this is a cause of skin rashes more than ethanol is. As toxicity of these molecules has never been evaluated (especially the synthetic ones), the encapsulation has the advantage of greatly dimmshing the skin penetration of these molecules. The capsules, which must be larger than 100 nm, release their volatiles to the environment long after the solvent has evaporated. Ethanol, furthermore, has the further major disadvantage of easily carrying the fragrance molecules across the skin barrier into sub-cutaneous layers.

[0089] Another advantage offered by the present invention lies in the possibility to disperse hydrophobic fragrances in water. Most of the fragrances indeed are oils and the perfume industry continues to use ethanol heavily. Avoiding the usage of ethanol is an unmet, urgent need in the quest of healthy and green cosmetics, reducing the frequency of perfume dermatitis in humans, as described by E. M. Jackson in American Journal of Contact Dermatitis 9 (1998)193-195.

[0090] The technology is also ideally suited to stabilize and protect chemically and photo-chemically labile or sensitive essential oils thereby enabling efficient utilization of essential oils in a number of applications, ranging from personal care to household, laundry and nutritional products.

[0091] A crucial advantage provided by the present invention lies in a positive consequence for human health and the environment, associated with the environmentally benign nature of the capsules made according to the present invention. Ubiquitous toxic synthetic fragrances, indeed, can be replaced by sol-gel derived micro-particles encapsulating unstable essential oils and other natural fragrances whose poor chemical and photochemical stability has thus far prevented widespread utilization. Protected by the sol-gel matrix, the essential oils become more resistant towards air, humidity, high temperature and solar light, namely all factors which can lead to the rapid evaporation and to the degradation of some active components. Once stabilized, essential oils (EOs) become a viable alternative in agriculture, food, cosmetic and pharmaceutical industries and medicine making possible a safer and better life in a protected environment. Beyond being fragrant, these natural plant products, indeed, consist of mixtures of several chemical compounds and possess antimicrobial, antioxidant and healing properties. [0092] Significant health and environmental benefits originate from the present invention used for the encapsulation of environmentally benign fragrances. Most of the synthetic nitro- and polycyclic musks used in perfumes, deodorants and detergents, are toxic and non-biodegradable. As a result, as shown by A. M. Peck, et al. Environmental Science & Technology 40 (2006) 5629, they tend to accumulate in the environment, and, as clearly demonstrated by J. L. Reiner, et al. Environmental Science & Technology 41 (2007) 3815, in the milk of human females.

[0093] The present invention relates to controlled release microparticles containing entrapped fragrance molecules, produced using the sol-gel technology. The microparticles can be core shell silica based particles, full matrix silica based particles, or multi-shell type particles.

[0094] According to some embodiments, the present invention provides controlled release microcapsules containing microencapsulated fragrance molecules, produced using the sol-gel technology.

[0095] The key technological challenges solved by the invention are twofold. In one aspect, the present invention relates to selectively controlling the release of the entrapped fragrances through tailored control of the properties of the organosilica shell, and in particular its HLB and textural properties (specific pore volume and surface area). In another aspect, the present invention relates to encapsulation of a mixture of fragrance chemicals which, upon release, preserves the original sensorial feeling, while controlling the release order, the release rate and thereby the duration of release of the fragrances. Each component of a mixture of fragrances can be released in a controlled manner from a single type of particle or each component can be individually controlled in different particles..

[0096] According to the present invention, the microcapsule is an organosilica capsule and has a core-shell structure. In one aspect, it is provided a process for preparing sol-gel microcapsules loaded with fragrance and aroma molecules from oil-in-water emulsions, comprising the steps of a) emulsifying the water insoluble solution, containing the sol-gel precursors and the functional molecules to be loaded, in an aqueous solution and b) stirring the emulsion obtained in step (a) with an acidic, neutral or basic aqueous solution to obtain loaded sol-gel microcapsules in a suspension, and c) optionally drying the mixture resulting from step b) with a mild evaporation treatment.

[0097] In one aspect, these sol-gel precursors are metal or semi-metal alkoxide monomers, or metal ester monomers, or semi-metal ester monomers or monomers of the formula M(R)n(P)m, wherein M is a metallic or semi metallic element, R is a hydrolyzable substituent, n is an integer from 2 to 6, P is a non polymerizable substituent and m is an integer from 0 to 6, or partially hydrolyzed and partially condensed polymer thereof, or any mixture thereof.

[0098] For example, said sol-gel precursors are silicon alkoxide monomers, or silicon ester monomers, or monomers of the formula Si(R)n(P)m, where R is a hydrolyzable substituent, n is an integer from 2 to 4, P is a non polymerizable substituent and m is an integer from 0 to 4, or partially hydrolyzed and partially condensed polymer thereof, or any mixture thereof.

[0099] In a further example, said sol-gel precursors are titanium alkoxide monomers, or titanium ester monomers, or monomers of the formula Ti(R)n(P)m, where R is a hydrolyzable substituent, n is an integer from 2 to 6, P is a non polymerizable substituent and m is an integer from 0 to 6, or partially hydrolyzed and partially condensed polymer thereof, or any mixture thereof.

[00100] In a further embodiment, the sol-gel precursors are zinc or zirconium alkoxide monomers, or zinc or zirconium ester monomers, or monomers of the formula Zn(R)n(P)m or Zr(R)n(P)m, where R is a hydrolyzable substituent, n is an integer from 2 to 6, P is a non polymerizable substituent and m is an integer from 0 to 6, or partially hydrolyzed and partially condensed polymer thereof, or any mixture thereof.

[00101] In another aspect, the microcapsules are fully alkylated organosilica particles obtained following the approach described in B. Fei et al. Chemistry Letters 35 (2006) 622, through self-catalytic sol-gel reaction of an alkyl-modified silane such as MTMS and an aminopropyl-modified silane such as 3-aminopropyl trimethoxysilane (ATMS) at oil/water interface without surfactant or other mediating reagents.

[00102] Examples of fragrance compound are not especially limited and include essential oils, citrus (orange, lemon and lime - oil top note fractions), magnolia and/or terpenes. Preferably the fragrance compound is added as a liquid. Typically about 0.001 to about 1 mole equivalents of the flavor compound can be used, based on the molar amount of the silicon alkoxide. Preferably, about 0.004 to about 0.02 mole equivalents are used.

[00103] In one embodiment, the present invention relates to the use of the sol-gel microencapsulation technology to create either a mixture of doped particles in which the release of different encapsulants takes place at similar rate, or particles containing a mixture in fragrances in which the release of different encapsulants takes place at the desired, tailored rate.

[00104] In another embodiment, the present invention relates to the synthesis of colloidal hydrophilic sol-gel particles entrapping the hydrophobic low molecular weight essential oils comprising the vast majority of compounds used in the fragrance industry, thus allowing the possibility to formulate in aqueous phase that can normally be performed in ethanol/water phase only.

[00105] In another embodiment, the present invention relates to capsules that release the encapsulated fragrance either by diffusion through the porous capsule shell or by rupture of the shell induced by mechanical forces.

[00106] In a further embodiment, the present invention relates to encapsulated perfume capsules wherein speed and duration of release is dictated by the volatility of the encapsulated perfume materials and by the shell chemical composition and textural properties. [00107] In one embodiment, the present invention relates to entrapped fragrance chemicals of high volatility when rapid release, and thus consumer perception of fragrance, is desired. [00108] In one embodiment, typical rates of release from the embedded silica capsules at room temperature are about 0.001 mmol/h, so that less than 5% fragrance leaches out of the capsule after 4 weeks.

[00109] The characteristics (described as typical, preferred and/or alternate) mentioned in the disclosure with regard to the process, method, fragrance or use can be combined or interverted freely. For example, mixture of two fragrances such as geraniol and citronellal can be used in a preferred amount (such as ca. 0.004 to ca. 0.02 mole equivalents) with a typical amount of the condensation catalyst (such as about 0.002 to about 0.12 mole equivalents) with a TEOS:MTMS (90:10 in molar terms) precursor mixture. Although all such combinations are not specifically nor literally recited, they are considered to unambiguously disclosed herein.

[00110] The fragrance-containing silica or organosilica micro-particle defined herein can be used on its own or be part of a fragrance bearing device or other supporting material.

[00111] The present invention provides, inter alia, fragrance-containing sol-gel microcapsules of tuneable or predetermined scent containing an active fragrance material in their core, prepared in a process comprising steps of emulsifying a water insoluble solution, comprising an appropriate amount of sol-gel precursors and the functional fragrance molecules to be loaded, in an aqueous solution with surfactants, followed by mixing and stirring the sol- gel precursor and fragrance oil emulsified mixture obtained with a neutral, acidic or basic aqueous solution to obtain loaded sol-gel microcapsule particles in suspension. [00112] In some embodiments, the active material is a single molecular fragrance or a combination of fragrances, including commercial fragrance mixtures such as perfumes.

[00113] In some embodiments, two or more sets of different capsules containing different fragrance chemicals having varying volatilities are prepared and combined in the desired proportion to obtain the require duration and rate of release, and thus of time- dependent perception.

[00114] In some embodiments, the fragrance or fragrances are combined with a co- solvent to tailor the overall hydrophilic-hydrophobic balance of the blend, or to modify the vapor pressure of the resulting microcapsule materials. [00115] In some embodiments, the fragrance is of natural origin, namely extracted from plant or animal source materials, and is derived from an essential oil or mixture thereof including, but not limited to, hyacinth, jasmine, magnolia, orchids, vanilla, and the like.

[00116] In some embodiments, the fragrance is of synthetic origin, including synthetic substances such as those found in many modern perfumes such as for instance Calone, salicylates and aromatic aldehydes artificially created either to match the fragrant compounds found in various natural fragrances or to create entirely new fragrances.

[00117] In some embodiments, the embedded fragrances are biodegradable chemicals which could not be used before because of the low chemical stability during processing, storage or usage.

[00118] In some embodiments, the process described above comprises the further step of isolating and washing the microcapsules by filtration and re-suspension in water, through centrifugation or by evaporation and re-suspension in water or by dialysis.

[00119] In some embodiments, the oil solution or the aqueous solution contain additives to improve the product, including preservatives, emulsifiers and biocides.

[00120] In some embodiments, other actives such as sunscreens, colors, antibacterials, and skin-used vitamins are co-entrapped in the capsule core.

[00121] In some embodiments, the sol-gel precursor is a metal or semi- metal alkoxide monomer, or a metal ester monomer, or a semi-metal ester monomer of the general formula M(R)n (P)m, wherein M is a metallic or semi metallic element such as Si, Al, Ti, Zn and Zr, R is a hydrolyzable substituent, n is an integer from 2 to 6, P is a non polymerizable substituent such as alkyl or aryl group and m is an integer from 0 to 6, or partially hydrolyzed and partially condensed polymer thereof, or any mixture thereof.

[00122] In some embodiments, the sol-gel precursor is selected from the group consisting of but not limited to TMOS, MTMS, TEOS and mixtures thereof. [00123] The present invention also provides fragrance-containing sol-gel microcapsules retaining the original scent of non-entrapped fragrance molecules, as substantially described and illustrated herein.

[00124] The present invention also provides a process for altering the odor of a mixture of fragrances through co-entrapment of odorant molecules in sol-gel capsules or combining a mixture of doped particles by tailoring the initial sol-gel chemistry so as to provide the required HLB level and textural properties to the encapsulant material.

[00125] The present invention also provides a process where the time dependence profile of the release of various fragrant components in a mixture is controlled by tailoring the porosity and HLB of the shell with suitably selected sol-gel monomers.

[00126] The present invention also provides a process for retaining the odor of a mixture of fragrances through entrapment of odorant molecules in different sol-gel capsules of similar structure and mixing these different capsules.

[00127] The present invention also provides a process to use hydrophilic odorant capsules to form water-based formulations avoiding the need of ethanol and thus preventing unwanted skin effects.

[00128] The present invention also provides a process to use the sol-gel encapsulation process described in claim 1 to protect and stabilize delicate biodegradable fragrance molecules or combination thereof.

[00129] The present invention mainly provides the products obtained by the process described above.

[00130] In some embodiments, the products are in a suspension form.

[00131] In some embodiments, the process described above further comprises the step of removing the water to obtain a final product in a powder form.

[00132] In some embodiments, the products described above are suspended in an aqueous medium and stabilized using biocides, suspending agents and a emulsion stabilizers. [00133] In some embodiments, the powder or the suspension consists of 0.1-10 micrometer spheroidal particles, and is semi-transparent or fully transparent when suspended in cosmetic or skin care formulations and applied to skin.

[00134] The present invention further provides functional products such as textiles and fabrics in which the fragrant capsules obtained by the process described above are deposited on these substrates.

[00135] The present invention further provides functional products such as soaps and body washes, shampoos and deodorants comprising he fragrant capsules obtained by the process described above. [00136] The present invention therefore provides, in one aspect, a composition comprising a plurality of fragrance-containing sol-gel micro-particles, the micro-particles comprising at least one active fragrance material, the fragrance material comprising at least one fragrant component, wherein the sol-gel micro-particles release each component of the fragrance material in a predetermined release profile. [00137] The term "sol-gel micro-particles" as used herein refers to any micro-particle prepared by the fabrication process described herein, and/or described in any disclosure relating to the sol-gel technique, such as described in WO 98/031333, WO 00/09652, WO 01/80823, WO 04/081222, WO 05/009604, WO 07/015243, etc.

[00138] The term "active fragrance material" as used herein refers to any compound or molecule, or a man-made or natural mixture of compounds or molecules, the presence of which is capable of being detected by a mammal, preferably a human.

[00139] The term "fragrant component" as used herein refers to any man-made or natural compound or molecule the presence of which is capable of being detected by a mammal, preferably a human. [00140] The term "predetermined release profile" as used herein refers to the desired odor, smell or fragrance being manipulated in at least one aspect relative to the odor, smell or fragrance of a corresponding active fragrance material or fragrant component in free form. The aspects of release profiles capable of being manipulated are many fold, including predetermining the rate of release of the active fragrance material or fragrant component from the micro-capsules, the intensity of release of the active fragrance material or fragrant component from the micro-capsules, the duration of release of the active fragrance material or fragrant component from the micro-capsules, the order of release of the active fragrance material or fragrant component from the micro-capsules, etc.

[00141] In some embodiments, the fragrance material comprises a plurality of fragrant components.

[00142] In some embodiments, at least two components of the plurality of fragrant components are released in different predetermined profiles. [00143] In some embodiments, at least two fragrant components are comprised in different sol-gel micro-particles.

[00144] In some embodiments, at least two fragrant components are comprised in the same sol-gel micro-particles.

[00145] In some embodiments, the sol-gel micro-particles are selected from the group consisting of full- matrix micro-particles, core/shell micro-particles, multi-shell micro-particles and any combination thereof. Each possibility represents a separate embodiment of the present invention.

[00146] The term "full-matrix micro-particles" as used herein refers to sol-gel micro- particles having a structure comprising polymerized sol-gel precursors. In some embodiments, the full-matrix micro-particles are non-porous, and the entrapped active fragrance materials or fragrant components are released from the micro-particle, at least partly, by diffusion. In other embodiments, the full-matrix micro-particles are porous, and the entrapped active fragrance materials or fragrant components are released from the micro-particle, at least partly, by convection. [00147] In some embodiments, the sol-gel micro-particles are at least partly coated by a metal-oxide layer, such as described in WO 07/015243. [00148] In some embodiments, the sol-gel micro-particles are porous full-matrix micro- particles, and wherein the at least one fragrant component is comprised in the internal cavities of the full-matrix micro-particles.

[00149] In some embodiments, the porous full-matrix micro-particles have a predetermined matrix hydrophilic-lipophilic balance (HLB) level, a predetermined matrix surface area and a predetermined matrix porosity level.

[00150] The term "hydrop ic-Upophilic balance (HLB)" as used herein is a measure of the degree to which a material is hydrophilic or lipophilic, determined by calculating values for the different regions of the material, as determined known techniques. [00151] In some embodiments, the sol-gel micro-particles are core/shell micro-particles, and wherein the at least one fragrant component is comprised in the core of the core/shell micro-particles.

[00152] The term "core/shell micro-particles" as used herein refers to sol-gel micro- particles having a structure comprising a liquid core encapsulated by polymerized sol-gel precursors. In some embodiments, the shell is non-porous, and the entrapped active fragrance materials or fragrant components are released from the micro-particle, at least partly, by diffusion. In other embodiments, the shell is porous, and the entrapped active fragrance materials or fragrant components are released from the micro-particle, at least partly, by convection. [00153] In some embodiments, the core/shell micro-particles have a predetermined shell hydropWlic-lipophilic balance (HLB) level, a predetermined shell surface area and a predetermined shell porosity level.

[00154] In some embodiments, the sol-gel micro-particles are multi-shell micro- particles, and wherein the at least one fragrant component is comprised in at least one shell of the multi-shell micro-particle.

[00155] The term "core/shell micro-particles" or "onion-shell micro-particles" are used interchangeably, and used herein to refer to sol-gel micro-particles having a structure comprising at least two layers of polymerized sol-gel precursors. In some embodiments, all the shells are non-porous, and the entrapped active fragrance materials or fragrant components are released from the micro-particle, at least partly, by diffusion. In other embodiments, all the shells are porous, and the entrapped active fragrance materials or fragrant components are released from the micro-particle, at least partly, by convection. In other embodiments, at least one of the shells is porous and at least one of the shells is non-porous, and the entrapped active fragrance materials or fragrant components are released from the micro-particle, at least partly, by diffusion.

[00156] In some embodiments, each shell of the multi-shell micro -particles has a predetermined shell hydrophilic-lipophilic balance (HLB) level, a predetermined shell surface area and a predetermined shell porosity level.

[00157] In some embodiments, the predetermined hydrophilic-lipophilic balance (HLB) level, the predetermined surface area and the predetermined porosity level regulate the release profile of the at least one fragrant component from the micro -particles.

[00158] In some embodiments, at least two fragrant components of the plurality of fragrant components have similar intrinsic volatilities.

[00159] The term "intrinsic volatility" as used herein refers to the tendency of a substance to vaporize while being in its free form, i.e. not attached, contained or mixed with another substance.

[00160] In some embodiments, at least two fragrant components have different release profiles when comprised in the micro-particles.

[00161] In some embodiments, at least two fragrant components of the plurality of fragrant components have different intrinsic volatilities.

[00162] In some embodiments, the at least two fragrant components have modified release profiles when comprised in the micro-particles. [00163] The term "modified release profile" as used herein refers to a volatile profile of a fragment component which is different from its intrinsic volatility profile. For example, two fragrant components having different intrinsic volatilities can be restricted to the same release profile by the present invention.

[00164] In some embodiments, the fragrant component is a natural fragrant component or a mixture thereof. Each possibility represents a separate embodiment of the present invention.

[00165] In some embodiments, the natural fragrant component is extracted from a plant or an animal. Each possibility represents a separate embodiment of the present invention.

[00166] In some embodiments, the natural fragrant component is an essential oil or a mixture thereof. Each possibility represents a separate embodiment of the present invention. [00167] In some embodiments, the essential oil is an essential oil obtained from a natural source selected from the group consisting of lavender, eucalyptus, thyme, balm, rosemary, sage, peppermint, basil, ginger bergamot, hyacinth, jasmine, magnolia, orchids and vanilla. It should be understood that any natural essential oils may be used by the present invention. Each possibility represents a separate embodiment of the present invention. [00168] In some embodiments, the fragrant component is a synthetic fragrant component or a mixture thereof. Each possibility represents a separate embodiment of the present invention.

[00169] In some embodiments, the synthetic fragrant component is selected from the group consisting of 7-Methylbenzo[b][l,4]dioxepin-3-one (Calone), salicylates aldehydes and aromatic aldehydes. Each possibility represents a separate embodiment of the present invention.

[00170] In some embodiments, the fragrant component is a biodegradable chemical of low chemical stability.

[00171] The term "biodegradable chemical of low chemical stability" as used herein refers to any chemical having a half-life period of up to an hour. For example, substances such as Nerol, and many essential oils, loose their initial intensity, or suffer a change in odor in very short periods. The present invention allows the extended use of such chemicals by entrapping them in the micro-capsules with provide structural and chemical protection.

[00172] In some embodiments, the sol-gel micro-capsules are prepared from a sol-gel precursor component selected from the group consisting of a metal, a semi-metal alkoxide, a metal ester, a semi-metal ester and any combination thereof. Each possibility represents a separate embodiment of the present invention.

[00173] In some embodiments, the sol-gel precursor is of the general formula

[00174] In some embodiments, M is selected from the group consisting of Si, Al, Ti, Zn and Zr. Each possibility represents a separate embodiment of the present invention.

[00175] In some embodiments, P is selected from the group consisting of alkyl and aryl group. Each possibility represents a separate embodiment of the present invention. [00176] In some embodiments, the sol-gel precursor is selected from the group consisting of 3-aminopropyl trimethoxysilane (ATMS), tetramethyl orthosilicate (TMOS), methyl trimethoxysilane (MTMS), tetraethyl orthosilicate (TEOS) and any combination thereof. Each possibility represents a separate embodiment of the present invention.

[00177] In some embodiments, at least one of the micro -particles further comprises a fragrant component solvent, wherein the solvent modifies the overall hydrophilic -hydrophobic balance (HLB) level of the micro-capsule, or the vapor pressure of the microcapsule. Each possibility represents a separate embodiment of the present invention.

[00178] In some embodiments, at least one of the micro-particles further comprises an additive. [00179] In some embodiments, the additive is selected from the group consisting of a preservative, an emulsifier, a biocide, a sunscreen compound, a color, a pigment, an antibacterial compound, a skin-used vitamin and any combination thereof. Each possibility represents a separate embodiment of the present invention.

[00180] In some embodiments, the additive is co-entrapped with the at least one fragrant component. [00181] In some embodiments, the composition described above is in suspension form.

[00182] In some embodiments, the composition described above is essentially devoid of alcohols.

[00183] In some embodiments, the composition described above is essentially devoid of ethanol. [00184] In some embodiments, the composition described above is in a powder form.

[00185] In some embodiments, the sol-gel micro-capsules have a diameter of about 0.1 to about 10 micrometer. In some embodiments, the sol- gel micro-capsules have a diameter of about 0.4 to about 4 micrometer. In some embodiments, the sol-gel micro-capsules have a diameter of about 1 micrometer. [00186] In some embodiments, the composition described above is semi-transparent or fully transparent when suspended in cosmetic or skin care formulations and applied to skin. Each possibility represents a separate embodiment of the present invention.

[00187] One of the main novel provisions of the present invention is the new ability to tailor a specific release profile for each and any fragrance material by manipulation the chemical environment by which this material is surrounded in the micro-particle. By predetermining the exact chemical environment in each micro-particle, one is now provided with the ability to master all aspects of fragrance material release.

[00188] Therefore, in some embodiments, the micro-capsules are combined in a predetermined proportion to obtain a predetermined perception profile; release profile; order of release of at least one fragrant component; duration of release of at least one fragrant component; or strength of the initial perception of at least one fragrant component. Each possibility represents a separate embodiment of the present invention. [00189] In some embodiments, the perception profile is a time-dependent perception profile, determined by the duration of perception or the rate of release of the fragrance material from the microcapsules.

[00190] In some embodiments, the micro-capsules are combined in a predetermined proportion to retain the original scent of the fragrance material before encapsulation.

[00191] In some embodiments, the composition described above is for use as an odor- producing material or as a malodor-masking agent in personal care products. Each possibility represents a separate embodiment of the present invention.

[00192] The present invention further provides, in an aspect, a textile or fabric comprising the composition described above. Each possibility represents a separate embodiment of the present invention.

[00193] The present invention further provides, in an aspect, a personal care product comprising the composition described above.

[00194] In some embodiments, the personal care product described above is selected from the group consisting of soap, a detergent, a fabric softener, a lotion, a cream, a body wash, a shampoo and a deodorant. Each possibility represents a separate embodiment of the present invention.

[00195] The present invention also provides, in an aspect, a method for manipulating the time-dependent release profile of a mixture of fragrant components, comprising encapsulating at least one fragrant component in sol-gel micro-capsules, wherein each one of the at least one fragrant components is encapsulated in micro-capsules having a predetermined hydropWlic-lipophilic balance (HLB) level, a predetermined surface area and a predetermined porosity.

[00196] The present invention also provides, in an aspect, a method for retaining the odor of a mixture of fragrant components, comprising encapsulating each fragrant component separately in sol-gel micro-capsule of similar structure, and mixing the micro-capsules. [00197] The present invention also provides, in an aspect, a method for preventing skin side-effects related to ethanol-based perfumes, comprising encapsulating at least one fragrant component in sol-gel hydrophilic micro-capsules substantially devoid of ethanol.

[00198] The present invention also provides, in an aspect, a method for protecting and stabilizing a biodegradable fragrant component, comprising entrapping the biodegradable fragrant component within the sol-gel micro-particles composition described above.

[00199] The following examples are meant to be construed as non- limiting to the scope of the invention and are to serve merely as illustrative embodiments.

EXAMPLES

Table 1. Solutions.

Example 1. Fabrication of Citronellal/Geraniol/TEOS/MTMS microcapsules.

[00200] A mixture of 125 mL of deionized water, 75 mL of ethanol, 1.5 mL of cetyl trimethylammonium bromide (CTAB), and 2.5 mL of ammonia solution (25 wt% NH₃ in water) was stirred at 700 rpm at room temperature. After 1 hour of stirring, the mixture was drop- wise added with a solution made of 8.2 mL tetraethyl orthosilicate (TEOS), 1.2 mL methyltrimethoxysilane (MTMS), 600 μL· Citronellal (rhodinal, 3,7-dimethyloct-6-en-l-al) and 600 μL Geraniol ((ira«5^,)-3,7-Dimethyl-2,6-octadien-l-ol). After 24 hours, the resulting microcapsules were collected by centrifugation, washed extensively with deionized water and left at room temperature for 1 day. Figure 1 depicts the resulting microcapsules in a X20,000 magnification. Figure 2 depicts several microcapsules in a XI 50,000 magnification, having a diameter of about 800nm.

Example 2. Fabrication of Citronellal /Geraniol/MTMS microcapsules.

[00201] A mixture of 150 mL of deionized water and 3 mL of 3- aminopropyltrimethoxysilane (ATMS) was added with a solution of 2 mL Citronellal and 2 mL Geraniol in 9 mL of methyltrimethoxysilane (MTMS). The resulting mixture was emulsified by fast magnetic stirring at 1000 rpm for 24 hours. The resulting microcapsules were washed extensively with deionized water and left at room temperature for 1 day. Figure 3 depicts the resulting microcapsules in a X50,000 magnification, having a diameter of about 1200nm

Example 3. Fabrication of Geraniol/TEOS and Citronellal/TEOS microcapsules.

[00202] A mixture of 125 mL of deionized water, 75 mL of ethanol, 1.5 mL of CTAB, and 2.5 mL of ammonia solution (25 wt% NH₃ in water) was stirred at 700 rpm at room temperature. To this mixture, a solution made of 10.2 mL TEOS and 1.2 ml Geraniol was added drop-wise. After 24 hours, the resultant microcapsules were collected by centrifugation, washed extensively with deionized water and left at room temperature for 1 day. The same procedure was employed for the entrapment of 1.2 mL of Citronellal.

Example 4. Odor alteration of fragrance-containing micro-particles.

[00203] The graphs depicted in Figures 4A and 4B show that co-entrapment of two fragrances in 10% -methyl-modified silica microcapsules (as described in Example 1) profoundly affects the release rate of the co-doped fragrance mixture. Extraction was conducted with 5 minute periods at 20 C (Figure 4A), followed by 30 minute periods at 50 C (Figure 4A). Hence, whereas extraction of Geraniol, an alcohol, with organic solvent is achieved with relative ease (half is extracted in 4 consecutive steps at 20 C, and the remaining entrapped fragrance is extracted prolonging the extraction time and rising temperature at 50 C), this is not the case for the aldehyde Citronellal. This remarkable difference is due to the strong affinity of the lipohilic Citronellal for the lipophilic organosilica matrix. Even a relatively low (10%, in molar terms) degree of organic modification is evidently enough to induce strong lipohilicity to the organically modified silica matrix, as also shown in Fidalgo et al. Chemistry of Materials, 17 (2005) 6686-6694.

Example 5. Top notes become low notes. [00204] The top note Nerol, a monoterpene found in the neroli essential oil widely used in perfumery, is entrapped in a organosilica microcapsule. A solution of methyltrimethoxysilane (MTMS, 9 mL) and Nerol (2 mL) was drop-wise added into a mixture of deionized water (150 mL) and 3-aminopropyltrimethoxysilane (ATMS, 3 mL) kept under fast (1000 rpm) stirring at room temperature. After stirring for 24 hours, a white microcapsule suspension was obtained. The solid was filtered and washed several times with deionized water and left at room temperature for 1 day.

[00205] Nerol ((Z)-3,7-dimethyl-2,6-octadien-l-ol) has a sweet, fresh rose odor, and its low boiling point (22.5 °C) causes it to evaporate rapidly upon contact with the heat of human body. Once entrapped in the organosilica capsules desribed herein, however, it becomes a bottom note as its odour now lasts for several weeks. The capsule prepared in Example 5 were suspended in water and an amount of the capsule suspension (100 microliter) was applied with a pipette to the arm of one of the Authors, whereas the neat fragrance was applied to the other arm Evaluation by rating the intensity of fragrance from the skin immediately after each application and again after 24 hours after application clearly shows that while the odour of the neat fragrance is practically disappered, the smell of the capsules is almost entirely retained after the 24 hour evaluation.

Example 6. Fabrication of bergamot oil/TEOS microcapsules.

[00206] Bergamot oil is a complex mixture of more than a thousand molecules. The more prominent molecules are represented in the Table 1. Table 1. Main molecules comprising bergamot oil out of more than 1,000 molecules.

[00207] Bergamot oil/TEOS microcapsules were synthesized with 100% TEOS as the silica source, to obtain an inorganic matrix which is completely hydrophilic (Figure 5A - magnification of X5,000; Figure 5B - magnification of X15,000).

[00208] The desorption profiles of free bergamot oil (Figure 6A) and bergamot oil encapsulated in 100% TEOS micro-particles (Figure 6B) were tested, and found to be highly similar, except for the component 2 (linalool) which could not be be detected in the encapsulated bergamot oil sample. It is interesting to note that linalool is the only compound out of the six detected presenting a polar OH group, which can interact with the Si-OH of the hydrophilic silica surface. With out being restricted to any theory or mechanism, this interaction may potentially stop, delay or decrease the desorption kinetics of linalool. Thus, theoretically, by controlling the silica matrix polarity, it would be possible to control the desorption kinetics and so control the smell composition.

Example 7. Bergamot oil evaporation from Bergamot oil/TEOS microcapsules.

[00209] The data and discussion provided in Example 5 may theoretically lead to the concept that if some molecules are retained by the matrix of the microcapsule, their smell should be released relatively slowly and therefore be detectable (e.g by the nose) for longer time periods in the microcapsules.

[00210] To test the validity of this concept, two samples were put on a glass surface. In one case, it was only pure bergamot oil, in the other it was encapsulated bergamot oil, but in respect to the same oil content. Table 2 summarizes the different observations taken during the experiment. Table 2. Temporal olfactory perception of two bergamot oil samples put on a glass surface.

[00211] To detect the molecules responsible for the detectable smells, the glass was washed with dichloromethane (DCM, methylene chloride, CH₂C1₂), and the microcapsules were extracted with DCM. The solutions were injected on to a gas chromatography-mass spectrometry (GC-MS) to identify the molecules. [00212] In the case of the free bergamot oil sample, the molecule responsible of the citrus smell was identified to be citropten. The concentration of this molecule was so small that the sample had to be concentrated to be able to detect the molecule via GC-MS. This molecule is present in a very small quantity in the original bergamot oil. The melting point of this molecule is nearly 150 °C, a solid in atmospheric condition. This is assumably the reason why a low citrus smell stayed on the glass surface. None of the 6 molecules described in Table 1 above was detected, and all seemed to be completely desorbed under atmospheric conditions.

[00213] In the case of the encapsulated bergamot oil sample, two molecules were easily detected by GC-MS; the polar moleacule linalool (Molecule #2 in Table 1), as suspected, and also the linalyl acetate (Molecule #1 in Table 1, also called bergamiol). This data demonstrates the high potential of encapsulated fragrances in a silica matrix of controlled polarity technology.

Claims

1. A composition comprising a plurality of fragrance-containing sol-gel micro-particles, said micro-particles comprising at least one active fragrance material, said fragrance material comprising at least one fragrant component, wherein said sol-gel micro-particles release each component of said fragrance material in a predetermined release profile.

2. The composition of claim 1, wherein said fragrance material comprises a plurality of fragrant components.

3. The composition of claim 2, wherein at least two components of said plurality of fragrant components are released in different predetermined profiles.

4. The composition of claim 2, wherein at least two fragrant components are comprised in different sol-gel micro-particles.

5. The composition of claim 2, wherein at least two fragrant components are comprised in the same sol-gel micro-particles.

6. The composition of claim 1 , wherein said sol- gel micro-particles are selected from the group consisting of full-matrix micro-particles, core/shell micro-particles, multi-shell micro- particles and any combination thereof.

7. The composition of claim 6, wherein said sol- gel micro-particles are at least partly coated by a metal-oxide layer.

8. The composition of claim 6, wherein said sol-gel micro-particles are porous full-matrix micro-particles, and wherein said at least one fragrant component is comprised in the internal cavities of said full-matrix micro-particles.

9. The composition of claim 8, wherein said porous full-matrix micro-particles have a predetermined matrix hydrophilic-lipophilic balance (HLB) level, a predetermined matrix surface area and a predetermined matrix porosity level.

10. The composition of claim 6, wherein said sol-gel micro-particles are core/shell micro- particles, and wherein said at least one fragrant component is comprised in the core of said core/shell micro-particles.

11. The composition of claim 10, wherein said core/shell micro-particles have a predetermined shell hydrophilic-lipophilic balance (HLB) level, a predetermined shell surface area and a predetermined shell porosity level.

12. The composition of claim 6, wherein said sol-gel micro-particles are multi-shell micro- particles, and wherein said at least one fragrant component is comprised in at least one shell of said multi-shell micro-particle.

13. The composition of claim 12, wherein each shell of said multi-shell micro-particles has a predetermined shell hydrophilic-lipophilic balance (HLB) level, a predetermined shell surface area and a predetermined shell porosity level.

14. The composition of any one of claims 9, 11 or 13, wherein said predetermined hydropWlic-lipophilic balance (HLB) level, said predetermined surface area and said predetermined porosity level regulate the release profile of said at least one fragrant component from said micro-particles.

15. The composition of claim 2, wherein at least two fragrant components of said plurality of fragrant components have similar intrinsic volatilities.

16. The composition of claim 15, wherein said at least two fragrant components have different release profiles when comprised in said micro-particles.

17. The composition of claim 2, wherein at least two fragrant components of said plurality of fragrant components have different intrinsic volatilities.

18. The composition of claim 17, wherein said at least two fragrant components have modified release profiles when comprised in said micro -particles.

19. The composition of claim 1, wherein said fragrant component is a natural fragrant component or a mixture thereof.

20. The composition of claim 19, wherein said natural fragrant component is extracted from a plant or an animal.

21. The composition of claim 20, wherein said natural fragrant component is an essential oil or a mixture thereof.

22. The composition of claim 21, wherein said essential oil is an essential oil obtained from a natural source selected from the group consisting of lavender, eucalyptus, thyme, balm, rosemary, sage, peppermint, basil, ginger bergamot, hyacinth, jasmine, magnolia, orchids and vanilla.

23. The composition of claim 1, wherein said fragrant component is a synthetic fragrant component or a mixture thereof.

24. The composition of claim 23, wherein said synthetic fragrant component is selected from the group consisting of 7-Methylbenzo[¾][l,4]dioxepin-3-one (Calone), salicylates aldehydes and aromatic aldehydes.

25. The composition of claim 1, wherein said fragrant component is a biodegradable chemical of low chemical stability.

26. The composition of claim 1, wherein said sol- gel micro-capsules are prepared from a sol-gel precursor component selected from the group consisting of a metal, a semi-metal alkoxide, a metal ester, a semi-metal ester and any combination thereof.

27. The composition of claim 26, wherein said sol-gel precursor is of the general formula

M(R)„(P)_m, wherein:

(i) M is a metallic or semi metallic element,

R is a hydrolysable substituent,

n is an integer from 2 to 6,

P is a non-polymerizable substituent, and

m is an integer from 0 to 6.

28 The composition of claim 27, wherein:

(i) M is selected from the group consisting of Si, Al, Ti, Zn and Zr; or (ii) P is selected from the group consisting of alkyl and aryl group.

29. The composition of claim 26, wherein said sol-gel precursor is selected from the group consisting of 3-aminopropyl trimethoxysilane (ATMS), tetramethyl orthosilicate (TMOS), methyl trimethoxysilane (MTMS), tetraethyl orthosilicate (TEOS) and any combination thereof.

30. The composition of to claim 1, wherein at least one of said micro-particles further comprises a fragrant component solvent, wherein said solvent modifies the overall hydrophilic- hydrophobic balance (HLB) level of said micro-capsule, or the vapor pressure of said microcapsule.

31. The composition of claim 1, wherein at least one of said micro-particles further comprises an additive.

32. The composition of claim 31, wherein said additive is selected from the group consisting of a preservative, an emulsifier, a biocide, a sunscreen compound, a color, a pigment, an antibacterial compound, a skin-used vitamin and any combination thereof.

33. The composition of claim 31, wherein said additive is co-entrapped with said at least one fragrant component.

34. The composition of claim 1, in a suspension form

35. The composition of claim 34, essentially devoid of alcohols.

36. The composition of claim 35, essentially devoid of ethanol.

37. The composition of claim 1, in a powder form.

38. The composition of claim 1, wherein said sol-gel micro-capsules have a diameter of about 0.1 to about 10 micrometer.

39. The composition of claim 38, being semi-transparent or fully transparent when suspended in cosmetic or skin care formulations and applied to skin.

40. The composition of claim 1, wherein said micro-capsules are combined in a predetermined proportion to obtain a predetermined:

(i) perception profile;

(ii) release profile;

(iii) order of release of at least one fragrant component;

(iv) duration of release of at least one fragrant component; or

(v) strength of the initial perception of at least one fragrant component.

41. The composition of claim 40, wherein said perception profile is a time-dependent perception profile, determined by the duration of perception or the rate of release of said fragrance material from said microcapsules.

42. The composition of claim 1, wherein said micro-capsules are combined in a predetermined proportion to retain the original scent of said fragrance material before encapsulation.

43. The composition of claim 1, for use as an odor-producing material or as a malodor- masking agent in personal care products.

44. A textile or fabric comprising the composition of claim 1.

45. A personal care product comprising the composition of claim 1.

46. The personal care product of claim 45, selected from the group consisting of soap, a detergent, a fabric softener, a lotion, a cream, a body wash, a shampoo and a deodorant.

47. A method for manipulating the time-dependent release profile of a mixture of fragrant components, comprising encapsulating at least one fragrant component in sol-gel microcapsules, wherein each one of said at least one fragrant components is encapsulated in microcapsules having a predetermined hydrophilic-lipophilic balance (HLB) level, a predetermined surface area and a predetermined porosity.

48. A method for retaining the odor of a mixture of fragrant components, comprising encapsulating each fragrant component separately in sol-gel micro-capsule of similar structure, and mixing said micro-capsules.

49. A method for preventing skin side-effects related to ethanol-based perfumes, comprising encapsulating at least one fragrant component in sol-gel hydrophilic microcapsules substantially devoid of ethanol.

50. A method for protecting and stabilizing a biodegradable fragrant component, comprising entrapping said biodegradable fragrant component within the sol-gel micro- particles composition of claim 1.