A light-responsive antioxidant preparation, a preparation method thereof, and applications thereof

Abstract

The present invention discloses a light-responsive antioxidant preparation, a preparation method thereof and an application. The method includes: dispersing or dissolving a biopolymer containing an amino group or a thiol group in a solvent, adjusting the pH of the solution to deprotonate it, and then adding an alcohol medium containing a cinnamate derivative to crosslink with it, obtaining a shell structure with light-responsive ability through Michael addition and Schiff base reaction, and endowing the shell structure with antioxidant property. After combining the shell structure with an appropriate core component, by forming Pickering emulsions or microcapsules, the ability to reduce particle size and control release after natural light irradiation is achieved. The preparation process of the present invention is simple, environmentally friendly and has high biosafety in the light-responsive mode.

Description

Technical Field

[0001] The present invention belongs to the fields of fine chemicals and cosmetics technology; more specifically, the present invention relates to a light-responsive antioxidant preparation, a preparation method thereof and applications, and the light-responsive antioxidant preparation comprises a light-responsive core-shell structure with antioxidant properties. Background Art

[0002] ‌The light-responsive core-shell structure‌ is a nanoscale ordered assembly structure formed by coating one kind of nanomaterial with another kind of nanomaterial through chemical bonds or other forces. This structure integrates the properties of the inner and outer materials and complements their respective deficiencies, and has unique functions and broad application prospects.

[0003] The characteristics of the light-responsive core-shell structure include but are not limited to: (a)‌Light responsiveness‌: The light-responsive core-shell structure can undergo physical or chemical changes under light irradiation, and this change can be used to trigger specific functions of the material, such as drug release, surface property change, etc.; (b)‌Core-shell structure‌: The core-shell structure usually consists of a "core" and a "shell", and the core and the shell can be different materials. Through the coating technology, the surface properties of the inner core are changed, improving the stability and dispersibility of the inner core; (c)‌Functional modification‌: The shell layer can adjust the overall hydrophilicity and hydrophobicity of the nanoparticles, protect the surface of the inner core from solvents, etc., and at the same time facilitate surface functional modification.

[0004] The application fields of the light-responsive core-shell structure include: (a)‌Biomedicine‌: In the biomedical field, the light-responsive core-shell structure is used to develop multifunctional nano-diagnosis and treatment platforms. For example, light-responsive porous core-shell structure nanoparticles can be used for cancer treatment and bioimaging; (b)‌Catalysis‌: In the field of catalysis, the light-responsive core-shell structure can be used for photocatalytic reactions to improve the catalytic efficiency and selectivity; (c)‌Batteries and gas storage‌: In the fields of batteries and gas storage, the light-responsive core-shell structure can be used to design high-performance battery materials and gas storage materials to improve the energy density and storage efficiency.

[0005] The preparation method of the light-responsive core-shell structure generally includes the following steps: (1)‌Select suitable core and shell materials‌: Select core and shell materials with specific optical and chemical properties according to application requirements; (2)‌Coating technology‌: Coat the shell material on the surface of the core material through chemical or physical methods to form an ordered core-shell structure; (3)‌Functional modification‌: Perform functional modification on the shell layer to achieve specific application functions.

[0006] In summary, due to its unique structural and functional characteristics, the light-responsive core-shell structure has shown broad application prospects in some fields. However, in the applications of the light-responsive core-shell structure in different fields, the technical means to be adopted and the technical obstacles to be overcome are very significantly different. For example, in fields such as pharmaceutical sustained release / delivery, light-responsive materials are mainly used to absorb infrared light to generate a thermal effect for excitation to promote the release of the content in the body; while the excitation method based on the thermal effect of infrared light usually requires the presence of metal or semi-metal components / nanoparticles, and the dose required for excitation is very high, which poses a great threat to skin health and is not conducive to applications in the cosmetics field. Up to now, the application of ultraviolet light-triggered light-responsive materials in the daily chemical industry is basically blank. Summary of the Invention

[0007] The object of the present invention is to provide a preparation method of a light-responsive antioxidant preparation, the light-responsive antioxidant preparation obtained by using the method and the application. The light-responsive antioxidant preparation specifically includes a light-responsive Pickering emulsion and microcapsules. On this basis, a cosmetics loaded with aromatic compounds is provided.

[0008] In the first aspect of the present invention, a method for preparing a light-responsive antioxidant preparation is provided, including: (1) mixing an alcohol medium of a cinnamate derivative with a biopolymer, performing a cross-linking reaction, and separating to obtain a cross-linking reaction product; (2) mixing the cross-linking reaction product with an aromatic compound to obtain a cosmetics preparation loaded with the aromatic compound and having light-responsive properties; wherein, the antioxidant preparation includes: a Pickering emulsion or a microcapsule.

[0009] In one or more embodiments, the antioxidant preparation is a Pickering emulsion, wherein: step (1) includes: dispersing the biopolymer (preferably dispersing in water), mixing with an alcohol medium containing a cinnamate derivative, adjusting the pH of the mixture to weakly alkaline (such as pH 8.5 ± 1), performing a cross-linking reaction, adjusting the cross-linked product to neutral, and freeze-drying to obtain nanoparticles; step (2) includes: redissolving the nanoparticles in (1), mixing and homogenizing with an aromatic compound in a hydrophobic phase (oil phase) to obtain a Pickering emulsion having light-responsive properties.

[0010] In one or more embodiments, step (1) includes:

[0011] A: Dispersing the biopolymer in water (preferably deionized water), fully mixing, placing at 4 ± 2 °C, and then placing at 90 ± 10 °C for incubation, and quickly cooling to room temperature to obtain a biopolymer dispersion;

[0012] B: Dissolve the cinnamate derivative in an alcohol medium (preferably the alcohol is ethanol, and the cinnamate derivative is dissolved in ethanol to form an alcohol solution with a concentration of 20 - 80 mM, 25 - 70 mM, 35 - 65 mM, 40 - 60 mM, or 45 - 55 mM), use copper ions as a catalyst, and hydrogen peroxide as an oxidant. Mix and oxidize at 10 - 30 °C to obtain an aqueous alcohol solution of the quinone-type compound;

[0013] C: Adjust the pH of the aqueous alcohol solution of the quinone-type compound to neutral, mix it with the biopolymer dispersion, and fully mix at a pH of 8.5 ± 1 (preferably 8.5 ± 0.5, more preferably 8.5 ± 0.3 or ± 0.2) for 2 - 8 h; adjust the reaction product to neutral and freeze-dry to obtain nanoparticles.

[0014] In one or more embodiments, step (2) includes:

[0015] D: Dissolve the nanoparticles in water (preferably deionized water), add the aromatic compound in the hydrophobic phase, and emulsify to obtain the Pickering emulsion.

[0016] In one or more embodiments, the mass concentration of the biopolymer is 1 - 10 wt%, preferably 1.5 - 8 wt%, more preferably 2 - 5 wt%.

[0017] In one or more embodiments, in A, stir at a speed of 600 ± 200 rpm (preferably 600 ± 150, 100, or 50 rpm) for 2 ± 1 h (preferably 2 ± 0.5 h); store at 4 ± 2 °C (preferably 4 ± 1 °C) for 12 ± 6 h (preferably 12 ± 4, 2, or 1 h); place in a water bath at 90 ± 10 °C (preferably 90 ± 8, 6, 4, or 2 °C) and maintain for 30 ± 20 min (preferably 30 ± 15, 10, or 5 min).

[0018] In one or more embodiments, in B, when oxidizing, add 3 ± 2 wt% (preferably 3 ± 1.5, 1, or 0.5 wt%) of hydrogen peroxide solution as an oxidant, and stir and oxidize at a speed of 300 ± 200 rpm (preferably 300 ± 150, 100, or 50 rpm) at 10 - 30 °C (such as 15, 20, 25 °C).

[0019] In one or more embodiments, in B, the concentration of copper ions in the solution is 0.05 - 2 mol%, more preferably 0.1 - 1.5 mol%, for example, 0.2, 0.3, 0.5, 0.7, 0.8, 1, 1.2, 1.5, or 1.8 mol%.

[0020] In one or more embodiments, in B, the volume ratio of the alcohol medium of the cinnamate derivative to the biopolymer dispersion is 1:5 to 20.

[0021] In one or more embodiments, in B, the molar ratio of the cinnamate derivative to hydrogen peroxide is 1:0.8 to 3 (preferably 1:1 to 5; more preferably 1:1 to 1.5).

[0022] In one or more embodiments, the concentration of the quinone compound in the aqueous alcohol solution is 10 to 120 mM; preferably 15 to 100 mM, such as 20, 30, 50, 80 mM.

[0023] In one or more embodiments, in C, the aqueous alcohol solution of the quinone compound is slowly adjusted to neutral with 0.5 ± 0.5 M (preferably 0.5 ± 0.4, 0.3, 0.2 or 0.1 M) sodium hydroxide, added to the biopolymer dispersion, and the pH of the mixture is adjusted to 8.5 to 9.0 with 1 M ± 0.6 M (preferably 1 ± 0.5, 0.3, 0.2 or 0.1 M) sodium hydroxide, and the mixture is stirred and reacted at 30 to 45 °C (such as 32, 35, 38, 40, 42 °C) at a speed of 600 ± 200 rpm (preferably 600 ± 150, 100 or 50 rpm) for 2 to 8 h (such as 3, 4, 5, 6 h).

[0024] In one or more embodiments, in C, after the reaction product is adjusted to neutral, it further includes: removing insoluble substances and harvesting the supernatant for freeze-drying.

[0025] In one or more embodiments, in D, the nanoparticles are dissolved in water (preferably deionized water), a hydrophobic phase (aromatic compound) is added, and emulsified with a high-speed disperser at a speed of 8000 ± 2000 rpm (preferably 8000 ± 1500, 1000 or 500 rpm) for 5 ± 4 min (preferably 0.5 ± 3, 2 or 1 min), and left standing overnight at 4 ± 2 °C (preferably 4 ± 1 °C) to obtain a Pickering emulsion.

[0026] In one or more embodiments, in step (2), the mass concentration of the nanoparticles is 0.5 to 20 mg / mL (such as 1, 2, 4, 6, 8, 10, 12 or 15 mg / mL).

[0027] In one or more embodiments, the volume fraction of the hydrophobic phase is 3 to 80 v / v% (such as 5, 10, 15, 20, 30, 40, 50, 60, 70, 74 or 75 v / v%).

[0028] In one or more embodiments, the antioxidant preparation is a microcapsule preparation, wherein: Step (1) includes: mixing and dispersing an alcohol medium containing a cinnamate derivative with a biopolymer, adding water to form a co-solvent; adjusting the pH of the mixture to weakly alkaline (such as pH 8.0 ± 0.6), performing a cross-linking reaction, adjusting the cross-linked product to neutral, and freeze-drying to obtain a grafted product; Step (2) includes: redissolving the grafted product obtained in (1), mixing it with an aromatic compound in the hydrophobic phase, and separating the portion with a molecular weight greater than 3500 Da to obtain a microcapsule preparation with photo-responsive properties.

[0029] In one or more embodiments, Step (1) includes:

[0030] A’: Dissolving the cinnamate derivative in an alcohol medium (preferably forming an alcohol solution with a cinnamate derivative concentration of 5 - 80 mM, more preferably 8 - 60 mM or 10 - 50 mM), using copper ions as a catalyst and hydrogen peroxide as an oxidant, mixing and oxidizing at 10 - 30 °C to obtain an aqueous alcohol solution of a quinone-type compound;

[0031] B’: Dispersing the biopolymer in the aqueous alcohol solution of the quinone-type compound, and then adding an equal volume of water (preferably deionized water) to form a co-solvent (an alcohol-water co-solvent);

[0032] C’: Adjusting the pH of the mixture to 8.0 ± 0.6 (preferably 8.0 ± 0.5, more preferably 8.0 ± 0.3 or ± 0.2), fully mixing at 30 - 45 °C for 2 - 8 h; adjusting the reaction product to neutral, and freeze-drying to obtain a grafted product.

[0033] In one or more embodiments, Step (2) includes:

[0034] D’: Dissolving the grafted product in water (preferably deionized water), adding an aromatic compound in the hydrophobic phase, and retaining the portion with a molecular weight greater than 3500 Da by dialysis to obtain a microcapsule preparation with photo-responsive properties.

[0035] In one or more embodiments, the mass concentration of the biopolymer is 0.1 - 2 wt%, preferably 0.15 - 1 wt%, more preferably 0.2 - 0.5 wt%.

[0036] In one or more embodiments, in A’, during oxidation, 3 ± 2 wt% (preferably 3 ± 1.5, 1 or 0.5 wt%) of a hydrogen peroxide solution is added as an oxidant, and stirring oxidation is performed at 10 - 30 °C (such as 15, 20, 25 °C) at a rotation speed of 300 ± 200 rpm (preferably 300 ± 150, 100 or 50 rpm).

[0037] In one or more embodiments, in A’, the copper ions include (but are not limited to) those from copper chloride, such as adding anhydrous copper chloride to form copper ions in solution. Preferably, the concentration of copper ions in the solution is 0.05 - 2 mol%, more preferably 0.1 - 1.5 mol%, for example, 0.2, 0.3, 0.5, 0.7, 0.8, 1, 1.2, 1.5 or 1.8 mol%.

[0038] In one or more embodiments, in A’, the molar ratio of the cinnamate derivative to hydrogen peroxide is 1:0.8 - 3 (preferably 1:1 - 5; more preferably 1:1 - 1.5).

[0039] In one or more embodiments, the concentration of the hydroalcoholic solution of the quinone compound is 5 - 80 mM, preferably 8 - 60 mM, more preferably 10 - 50 mM, such as 20, 30, 40 mM.

[0040] In one or more embodiments, in C’, 1 M ± 0.6 M (preferably 1 ± 0.5, 0.3, 0.2 or 0.1 M) sodium hydroxide is used to adjust the pH of the co - solvent to pH 8.0 ± 0.6, and the mixture is stirred at 800 ± 200 rpm (preferably 800 ± 150, 100 or 50 rpm) at 30 - 45 °C (such as 32, 35, 38, 40, 42 °C) for 2 - 8 h (such as 3, 4, 5, 6 h).

[0041] In one or more embodiments, in D’, water (preferably deionized water) is used as the dialysis fluid, and the dialysis fluid can be changed during the dialysis process.

[0042] In one or more embodiments, in step (2), the mass concentration of the graft is 0.02 - 0.8 wt% (such as 0.05, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 wt%).

[0043] In one or more embodiments, the volume fraction of the hydrophobic phase is 1 - 20 v / v% (such as 2, 3, 5, 6, 8, 10, 12 or 15 v / v%).

[0044] In one or more embodiments, the cinnamate derivative includes a compound with the following structural formula:

[0045] ;

[0046] Among them, R1 is selected from long - chain alkanes, long - chain alkenes, benzene or homologues of benzene; R 2～ R6 are each independently selected from a hydrogen atom, a hydroxyl group, an aldehyde group, a methoxy group or a carbonyl group;

[0047] The cinnamate derivatives include: phenethyl caffeate, benzyl caffeate, caffeic acid benzyl ester, n-octyl caffeate, or caffeic acid 1,1-dimethylallyl ester, or a combination thereof.

[0048] In one or more embodiments, the biopolymer includes a protein or a polysaccharide; the antioxidant preparation is a Pickering emulsion, and the biopolymer includes: soy protein isolate, soy protein hydrolysate, whey protein, whey protein isolate, lactoferrin, sericin, ovalbumin, vitellin, collagen, hydrolyzed collagen, bovine serum albumin, ε-polylysine or polylysine, or a combination thereof.

[0049] In one or more embodiments, the antioxidant preparation is a microcapsule, and the biopolymer includes: carboxymethyl chitosan, N,N,N-trimethyl chitosan, hydroxypropyl chitosan, chitosan, aminated dextran, aminated hyaluronic acid, or a combination thereof.

[0050] In one or more embodiments, the hydrophobic phase (oil phase) includes: peppermint essential oil, limonene, tea tree oil, eucalyptus oil, soybean oil, castor oil, palm oil, jojoba oil, shea butter, almond oil, grape seed oil, tea seed oil, lavender oil or fatty acid esters, or a combination thereof.

[0051] In one or more embodiments, the alcohol medium includes: ethanol, isopropanol or tert-butanol, or a combination thereof.

[0052] In one or more embodiments, the copper ions include (but are not limited to) copper ions from copper chloride or copper sulfate, for example, adding anhydrous copper chloride or anhydrous copper sulfate to form copper ions in the solution.

[0053] In one or more embodiments, the quinone-type compounds include: semiquinone compounds, o-benzoquinone compounds or radical polymers.

[0054] In another aspect of the present invention, there is provided a photo-responsive antioxidant preparation obtained by the method described in any one of the foregoing.

[0055] In one or more embodiments, the photo-responsive antioxidant preparation is a Pickering emulsion, wherein the average particle size of the nanoparticles is 20-50 nm, and the particle size of the nanoparticles is significantly reduced after illumination.

[0056] In one or more embodiments, the photo-responsive antioxidant preparation is a Pickering emulsion, and its droplet diameter is 200 nm-1.5 um; the diameter of the droplets is significantly reduced after illumination.

[0057] In one or more embodiments, the light-responsive antioxidant preparation is a microcapsule preparation, wherein the average particle size of the microcapsules is 500 nm to 1.5 um, and the particle size of the microcapsules is significantly reduced after illumination.

[0058] In one or more embodiments, the light includes ultraviolet light or near-infrared light.

[0059] In one or more embodiments, the light can be natural light, and the natural light contains ultraviolet light or near-infrared light.

[0060] In another aspect of the present invention, there is provided an application of the light-responsive antioxidant preparation for preparing a cosmetic or skin care product, and the aromatic compound can be controlled released.

[0061] Other aspects of the present invention will be apparent to those skilled in the art from the disclosure herein. Description of the Drawings

[0062] Figure 1 The UV-visible absorption spectrum of the nanoparticles prepared in Example 1, which is used to characterize the properties of the nanoparticles. The wavelength is the abscissa, and the absorbance (a.u.) is the ordinate, where a is soy protein isolate and b is the nanoparticles.

[0063] Figure 2 The dynamic light scattering (DLS) of the nanoparticles prepared in Example 1, which is used to characterize the particle size change of the prepared nanoparticles before and after UV UV-340 illumination. The particle size (d.nm) is the abscissa, and the volume percentage (%) is the ordinate.

[0064] Figure 3 The ABTS and FRAP diagrams of the nanoparticles prepared in Example 1, which are used to characterize the in vitro antioxidant ability of the nanoparticles. Based on 10 mg / mL nanoparticles, the dilution factor is the abscissa, and TEAC (mmol / L) is the ordinate, where (a) is the ABTS diagram of the grafted product, (b) is the FRAP diagram of the grafted product, and TEAC represents the concentration of the Trolox positive control.

[0065] Figure 4 The TEM diagram of the Pickering emulsion prepared in Example 2. [[ID=3l]]

[0066] Figure 5 The SEM diagram of the Pickering emulsion prepared in Example 2.

[0067] Figure 6 The DLS diagram of the Pickering emulsion prepared in Example 2, which is used to characterize the particle size change of the prepared Pickering emulsion before and after UV UV-340 illumination.

[0068] Figure 7, DLS graph of the Pickering emulsion prepared in Example 3, used to characterize the particle size change of the prepared Pickering emulsion before and after ultraviolet UV-340 irradiation.

[0069] Figure 8 , DLS graph of the Pickering emulsion prepared in Example 4, used to characterize the particle size change of the prepared Pickering emulsion before and after ultraviolet UV-340 irradiation.

[0070] Figure 9 , DLS graph of the Pickering emulsion prepared in Example 4, used to characterize the zeta potential change of the prepared Pickering emulsion before and after ultraviolet UV-340 irradiation. The zeta potential (mv) is the abscissa and the total count is the ordinate.

[0071] Figure 10 , Appearance graphs of the high internal phase emulsion in Example 5 after natural light irradiation, ultraviolet light irradiation, storage in the dark at 40 °C, and storage in the dark at room temperature, intuitively showing the release of the oil phase in the emulsion. The high internal phase Pickering emulsion is a semi-solid cream-like when stable. If unstable precipitation of the oil phase occurs, phase transition will occur. No obvious phase transition occurred during heat treatment and storage in the dark at room temperature, while both natural light irradiation and ultraviolet light irradiation can promote the formation of phase transition. This indicates that the photo-responsive behavior of the nanoparticles in the emulsion leads to the controlled release of the oil phase, that is, the phase transition process occurs.

[0072] Figure 11 , Fourier transform infrared spectroscopy graphs of the grafted product and carboxymethyl chitosan in Example 6, used to characterize the properties of the grafted product. The wavelength (nm) is the abscissa, where a is carboxymethyl chitosan and b is the grafted product.

[0073] Figure 12 , ABTS and FRAP graphs of the grafted product prepared in Example 6, used to characterize the in vitro antioxidant ability of the grafted product. Based on 1 mg / mL of the grafted product, the dilution factor is the abscissa and TEAC (mmol / L) is the ordinate, where (a) is the ABTS graph of the grafted product and (b) is the FRAP graph of the grafted product. TEAC represents the concentration of the Trolox positive control.

[0074] Figure 13 , Laser confocal microscopy graphs of the microcapsules prepared in Example 7, used to characterize the loading of the microcapsules (a - c).

[0075] Figure 14 , Contact angle control graphs in Example 8, used to characterize the amphiphilicity of the grafted product. The contact angle (θ) is the angle between the water and air interface, where (a) is carboxymethyl chitosan and (b) is the grafted product.

[0076] Figure 15, the DLS graph of Example 8 was used to characterize the particle size change of the microcapsules before and after ultraviolet (UV)-340 light irradiation. The particle size (d, nm) was used as the abscissa, and the volume percentage (%) was used as the ordinate.

[0077] Figure 16 , the contact angle control graph of Example 9 was used to characterize the amphiphilicity of the grafted product. The contact angle (θ) was the angle between the water and air interfaces, where (a) was carboxymethyl chitosan and (b) was the grafted product.

[0078] Figure 17 , the DLS graph of the microcapsules prepared in Example 9 was used to characterize the particle size change of the microcapsules before and after ultraviolet (UV)-340 light irradiation.

[0079] Figure 18 , the graph showing the change in the release amount of the microcapsules prepared in Examples 8 and 9 with the ultraviolet (UV)-340 light irradiation time. The placement time (h) was used as the abscissa, and the release rate (%) of the core substance was used as the ordinate. The ultraviolet (UV)-340 light irradiation groups were a and b, where a was the microcapsules prepared in Example 8 and b was the microcapsules prepared in Example 9. The control was the microcapsules prepared in Example 3 under dark conditions. Detailed implementation manners

[0080] Through in-depth research, a class of light-responsive and antioxidant preparations (compositions) was revealed. The preparations include Pickering emulsions or microcapsules, which can form cosmetics or skin care products, or be used as active ingredients in cosmetics or skin care products. The present invention also provides a preparation method for the preparations.

[0081] In the daily chemical industry, light-responsive materials that can control the release of core components using light signals are rarely successfully prepared. The present invention has changed this situation. Specifically: (1) Considering the trade-off between the material coating performance and light responsiveness, in the daily chemical industry, the coating ability of responsive materials has always been a problem; while the present invention utilizes the characteristics of Pickering emulsions to prepare responsive materials that can load up to 80% of the oil phase at most. (2) The preparation of most light-responsive materials is relatively complex and costly; while the present invention uses a simple preparation method, which belongs to biomimetic synthesis and has high economic benefits and is suitable for the cosmetics industry. (3) The daily chemical industry has relatively high requirements for biological safety. The present invention brings beneficial antioxidant properties during the preparation process, and the introduction of protein and polysaccharide components increases biocompatibility. (4) In the daily chemical industry, there has been no reported responsive method that can cause a decrease in the particle size of emulsions / microcapsules under light irradiation, which is a major difficulty, while the present invention has successfully obtained such products.

[0082] In the present invention, ultraviolet or near-infrared light (phototherapy band) in natural light is innovatively utilized to excite the shell structure, enabling mild cis-trans isomerization and physical changes at relatively low concentrations without relying on the triggering method of thermal effects (metal / semimetal components), thus having unique application advantages in cosmetics.

[0083] Core-shell structure

[0084] The core-shell structure is an ordered assembly structure formed by coating one material on the surface of another material.

[0085] In the present invention, cinnamate derivatives are applied, in which the cinnamate group hydrophobically modifies biopolymers (such as proteins or polysaccharides) to obtain modified biopolymers and serve as the shell structure. After adding appropriate core components, the shell structure and the core components are assembled under optimized conditions to form a core-shell structure, including Pickering emulsions or microcapsules.

[0086] After the modified biopolymer of the shell structure obtained in the present invention is irradiated with light (preferably ultraviolet light), the cinnamate group in the shell undergoes cis-trans isomerization, resulting in a decrease in the particle size of the core-shell structure and extrusion rearrangement, achieving controlled release of the core components.

[0087] As used in the present invention, the "hydrophobic phase" and the "oil phase" can be used interchangeably.

[0088] Antioxidant photo-responsive core-shell structure: Pickering emulsion

[0089] A Pickering emulsion is an emulsion system stabilized only by solid particles. During the preparation of Pickering emulsions using proteins, the semi-solid shell layer usually exists in the form of hydrocolloids, such as gels or films. The Pickering emulsion prepared in the present invention does not require the presence of surfactants and can bring strong stability to the emulsion with very little addition.

[0090] The photo-responsive Pickering emulsion of the present invention is prepared by dispersing a biopolymer in deionized water, adjusting the pH of the solution to deprotonate it, and then adding an alcohol medium containing a cinnamate derivative to crosslink with it. After sufficient reaction, nanoparticles are obtained. The obtained nanoparticles are freeze-dried and then redissolved in deionized water as an emulsifier and mixed and homogenized with an oil phase to obtain a photo-responsive Pickering emulsion.

[0091] In the structure of the cinnamate derivative, the electron-deficient benzene ring containing α,β-unsaturated aldehyde ketone can undergo Michael addition and Schiff base reactions with the electron-rich sulfhydryl or amino groups of the biopolymer, thereby obtaining a covalent crosslinking product.

[0092] In the cinnamate derivative, the vinyl group has the ability of photoinduced cis-trans isomerization, and the side chain group has hydrophobicity, thus serving as the photo-responsive group and the hydrophobic part of the biopolymer. By modifying the surface or inner surface of the nanoparticles to enhance their hydrophobicity to make them suitable as emulsifiers, a Pickering emulsion with photo-responsive ability can be obtained.

[0093] As a preferred embodiment of the present invention, a method for preparing a nanoparticle-stabilized Pickering emulsion includes:

[0094] A1: Dispersing the biopolymer in deionized water at a certain ratio, stirring at a speed of 600 r for 2 h and then storing at 4 °C for 12 h. Subsequently, placing it in a 90 °C water bath for 30 min and quickly cooling to room temperature to obtain a biopolymer dispersion;

[0095] B1: Dissolving the cinnamate derivative in an alcohol medium, adding copper ions as a catalyst. Subsequently, adding a 3 wt% hydrogen peroxide solution as an oxidant and stirring and oxidizing at a speed of 300 r at 10 - 30 °C to obtain an aqueous alcohol solution of a quinone-type compound;

[0096] C1: Slowly adjusting the pH of the aqueous alcohol solution of the quinone-type compound to neutral with 0.5 M sodium hydroxide, and then adding it to the biopolymer dispersion. Adjusting the pH of the mixture to 8.5 - 9.0 with 1 M sodium hydroxide and stirring and reacting at a speed of 600 r at 30 - 40 °C for 2 - 3 h;

[0097] D1: Extracting the reaction product, dissolving it in deionized water to obtain an aqueous solution of nanoparticles, then adding a certain volume of the oil phase and emulsifying with a high-speed disperser at a speed of 8000 rpm for 5 min, and standing overnight at 4 °C to obtain a Pickering emulsion.

[0098] According to some preferred embodiments of the present invention, the preparation method further includes: when stratification occurs after the biopolymer is hydrated, first stirring and dispersing, and then performing water bath heating at 90 °C after the solution is homogeneous and stable.

[0099] According to some preferred embodiments of the present invention, the mass concentration of the biopolymer is 2 - 5 wt%.

[0100] According to some preferred embodiments of the present invention, the alcohol medium includes: ethanol, isopropanol, tert-butanol. More preferably, the alcohol medium is selected from ethanol.

[0101] According to some preferred embodiments of the present invention, the concentration of the aqueous alcohol solution of the quinone-type compound is 15 - 100 mM.

[0102] According to some preferred embodiments of the present invention, the copper ion catalyst comprises copper ions from anhydrous copper chloride and anhydrous copper sulfate. More preferably, the copper ion catalyst is from anhydrous copper chloride.

[0103] According to some preferred embodiments of the present invention, the molar concentration of the copper ion catalyst is 0.1 - 0.5 mol%.

[0104] According to some preferred embodiments of the present invention, the molar ratio of the cinnamate derivative to hydrogen peroxide (such as 3 wt% hydrogen peroxide solution) is 1:1 - 1.5.

[0105] According to some preferred embodiments of the present invention, the volume ratio of the alcohol medium of the cinnamate derivative to the biopolymer dispersion is 1:5 - 20.

[0106] According to some preferred embodiments of the present invention, the quinone compounds include: semiquinone compounds, o - benzoquinone compounds, and radical polymers.

[0107] According to some preferred embodiments of the present invention, the reaction pH is preferably 8.5, and the temperature is preferably 35°C.

[0108] According to some preferred embodiments of the present invention, the extraction of the reaction product comprises the following steps: adjusting the obtained mixture back to pH 7.0 with 0.5 M hydrochloric acid and separating the insoluble matter therein, and subjecting the obtained clear liquid to freeze - drying to obtain the nanoparticles.

[0109] According to some preferred embodiments of the present invention, the mass concentration of the nanoparticles is 1 - 10 mg / mL.

[0110] According to some preferred embodiments of the present invention, the volume fraction of the oil phase is 5 - 74 v / v%.

[0111] According to some preferred embodiments of the present invention, the cinnamate derivative is selected from one or more of phenethyl caffeate, benzyl caffeate, caffeic acid octyl ester, caffeic acid - 1,1 - dimethylallyl ester.

[0112] According to some preferred embodiments of the present invention, the biopolymer is selected from one or more of soy protein isolate, soy protein hydrolysate, whey protein, whey protein isolate, lactoferrin, sericin, ovalbumin, vitellin, collagen, hydrolyzed collagen, bovine serum albumin, ε - polylysine, polylysine.

[0113] According to some preferred embodiments of the present invention, the oil phase is selected from one or more of peppermint essential oil, tea tree oil, eucalyptus oil, soybean oil, castor oil, palm oil, jojoba oil, shea butter, almond oil, grape seed oil, and tea seed oil.

[0114] According to some preferred embodiments of the present invention, the average particle size of the nanoparticles is 20 - 50 nm, and the average droplet diameter of the Pickering emulsion is 200 nm - 1.5 μm.

[0115] In the above preparation method of the present invention, the biopolymer is first subjected to thermal denaturation treatment to break disulfide bonds and hydrophobic interactions to increase its solubility in the water-based system, obtaining nanoparticle aggregates. After the oxidation reaction of the cinnamate derivative, various quinone-type compounds containing electron-deficient structures can be obtained. With the help of an alcohol medium, the quinone-type compounds are uniformly dispersed into the biopolymer, and Michael addition or Schiff base reaction occurs with the amino acid side chains containing sulfhydryl or amino groups in the biopolymer.

[0116] The vinyl group in the cinnamate derivative is the key group for photoisomerization. Copper ions can not only catalyze the oxidation of the cinnamate derivative through coordination, but also enhance the electrophilicity of the quinone carbonyl as a Michael acceptor in the subsequent reaction, inhibiting the participation of the vinyl ester group in the Michael addition reaction. Trace copper ions in the system have no adverse effects.

[0117] In the subsequent reaction, after the more hydrophilic nanoparticle aggregates and the more hydrophobic quinone-type compounds undergo covalent crosslinking, modified nanoparticles are formed. Due to the presence of cinnamate groups on the particle surface, the nanoparticles acquire photo-responsiveness. The Pickering emulsion is stabilized by a shell structure composed of nanoparticles. Once the nanoparticles in the shell layer are excited by ultraviolet UV-340 light, changes in particle size and polydispersity occur, triggering the restructuring of the emulsion interface structure, causing the emulsion droplet diameter to decrease and affecting the stability of the emulsion.

[0118] The technical solution for preparing the Pickering emulsion of the present invention has at least the following excellent technical effects:

[0119] (1) The preparation methods of the present invention all use non-toxic or low-toxic solvents, have simple reaction steps, low requirements for equipment, low energy consumption, simple process conditions, and simple post-treatment.

[0120] (2) The present invention can endow the modified nanoparticles with photo-responsiveness during preparation. The cinnamate derivative on the particle surface undergoes cis-trans isomerization after ultraviolet UV-340 light irradiation, resulting in a decrease in the particle size and PDI of the nanoparticles.

[0121] (3) The catalyst used in the present invention has a secondary catalytic effect, increasing the utilization rate.

[0122] (4) The Pickering emulsion prepared by the present invention has unique light-responsive behavior. The dynamic changes of the nanoparticles after UV-340 light irradiation will trigger the restructuring of the emulsion interface structure, resulting in the decrease of the emulsion droplet diameter and PDI. When the oil phase concentration in the emulsion is ≥74%, UV-340 light irradiation will cause the phase change of the emulsion and the precipitation of the oil phase, achieving the effect of controlled release.

[0123] (5) The nanoparticles and Pickering emulsion prepared by the present invention have excellent biosafety. The nanoparticles have excellent emulsifying properties and can prepare high internal phase emulsions at extremely low concentrations.

[0124] Antioxidant light-responsive core-shell structure: microcapsule

[0125] A microcapsule (Microcapsule) is a tiny closed structure composed of a solid, liquid or gas core substance and an external film-forming material. So far, there has been no report on the method of preparing modified polysaccharides and using them simultaneously as the shell structure and light-responsive materials to prepare microcapsules by self-assembly.

[0126] The light-responsive microcapsule of the present invention is prepared by dissolving a biopolymer in deionized water, adjusting the pH of the solution to deprotonate it, and then adding an alcohol medium containing a cinnamate derivative to crosslink it. After sufficient reaction, a graft with light-responsive ability is obtained in a co-solvent. The obtained graft is freeze-dried, redissolved in a co-solvent, mixed with an oil phase, and then the co-solvent is removed to obtain a light-responsive microcapsule.

[0127] In the structure of the cinnamate derivative, the electron-deficient benzene ring containing α, β-unsaturated aldehyde ketone can undergo a Michael addition reaction with the electron-rich amino group of the biopolymer, thereby obtaining a covalent crosslinking product.

[0128] In the cinnamate derivative, the vinyl group has the ability of photoinduced cis-trans isomerization, and the side chain group has hydrophobicity, thereby serving as the light-responsive group and hydrophobic part of the biopolymer. The biopolymer serves as the hydrophilic part, thus forming a graft structure and self-assembling into a light-responsive microcapsule.

[0129] As a preferred embodiment of the present invention, a method for preparing a microcapsule includes:

[0130] A2: Dissolve the cinnamate derivative in an alcohol medium, and add copper ions as a catalyst. Subsequently, quickly add a 3wt% hydrogen peroxide solution as an oxidant, and stir and oxidize at a rotation speed of 300 r at 10-30 °C to obtain an aqueous alcohol solution of a quinone-type compound.

[0131] B2: Disperse the biopolymer in the aqueous alcohol solution of the quinone-type compound according to a certain ratio, and then add an equal volume of deionized water to form a co-solvent.

[0132] C2: Adjust the pH of the co-solvent to 7.5 - 8.0 using 1 M sodium hydroxide, and stir the reaction at 800 r / min for 6 h at 35 - 45 °C.

[0133] D2: Extract the reaction product, redissolve the grafted product in the alcohol-water co-solvent, add a certain volume of the hydrophobic phase, and then dialyze to remove the alcohol solvent to obtain microcapsules loaded with the hydrophobic phase.

[0134] According to some preferred embodiments of the present invention, the preparation method further includes: when the biopolymer cannot be completely dissolved in the co-solvent, add a certain volume of deionized water until it is completely dissolved.

[0135] According to some preferred embodiments of the present invention, the mass concentration of the biopolymer is 0.2 - 0.5 wt%.

[0136] According to some preferred embodiments of the present invention, the alcohol medium includes: tert-butanol, ethanol, isopropanol. More preferably, the alcohol medium is selected from tert-butanol.

[0137] According to some preferred embodiments of the present invention, the concentration of the hydroquinone compound in the water-alcohol solution is 10 - 50 mM.

[0138] According to some preferred embodiments of the present invention, the copper ion catalyst includes anhydrous copper chloride, anhydrous copper sulfate. More preferably, the copper ion catalyst is selected from anhydrous copper chloride.

[0139] According to some preferred embodiments of the present invention, the molar concentration of the copper ion catalyst is 0.1 - 1 mol%.

[0140] According to some preferred embodiments of the present invention, the molar ratio of the cinnamate derivative to hydrogen peroxide (such as a 3 wt% hydrogen peroxide solution) is 1:1 - 1.5.

[0141] According to some preferred embodiments of the present invention, the hydroquinone compound includes: semiquinone compounds, o-benzoquinone compounds, and radical polymers.

[0142] According to some preferred embodiments of the present invention, the reaction pH is preferably 7.5, and the temperature is preferably 40 °C.

[0143] According to some preferred embodiments of the present invention, the extraction of the reaction product includes: adjusting the product to pH 7.0 using 0.1 M acetic acid, separating the insoluble matter of the reaction product, and freeze-drying the obtained clear liquid to obtain the grafted product.

[0144] According to some preferred embodiments of the present invention, the mass concentration of the grafted product is 0.05 - 0.2 wt%.

[0145] According to some preferred embodiments of the present invention, the volume fraction of the hydrophobic phase is 1 to 10%.

[0146] According to some preferred embodiments of the present invention, the cinnamate derivative is selected from one or more of phenethyl caffeate, benzyl caffeate, caffeic acid benzyl ester, n-octyl caffeate, and 1,1-dimethylallyl caffeate.

[0147] According to some preferred embodiments of the present invention, the biopolymer is selected from one or more of carboxymethyl chitosan, N,N,N-trimethyl chitosan, hydroxypropyl chitosan, chitosan, aminated dextran, and aminated hyaluronic acid.

[0148] According to some preferred embodiments of the present invention, the hydrophobic phase is selected from one or more of limonene, lavender oil, peppermint essential oil, tea tree oil, eucalyptus oil, and fatty acid esters.

[0149] According to some preferred embodiments of the present invention, the alcohol solvent is tert-butanol.

[0150] According to some preferred embodiments of the present invention, the dialysis solution during dialysis is deionized water, the molecular weight cut-off of the dialysis bag is 3500 Da, the dialysis time is 6 to 12 h, and the water is changed every 3 h.

[0151] According to some preferred embodiments of the present invention, the contact angle of the graft at the air-water interface is ≥60°, and the average particle size of the microcapsules is 500 nm to 1.5 µm.

[0152] In the above preparation method of the present invention, after the cinnamate derivative undergoes an oxidation reaction, a variety of quinone-type compounds containing an electron-deficient structure can be obtained. A Michael addition reaction occurs with the amino-containing side chain in the biopolymer by forming a co-solvent. In addition, tert-butanol, as a bulky solvent, can effectively inhibit transesterification during the reaction and is also beneficial for the lyophilization of the product.

[0153] In subsequent processing, the covalently crosslinked product will form a porous aerogel after freeze-drying, maintaining the structural stability. Since the cinnamate group has photo-responsiveness, and the microcapsules are self-assembled from the graft, once the graft undergoes cis-trans isomerization under UV-34o light irradiation, this will directly or indirectly affect the spatial arrangement of the microcapsule shell layer, thereby squeezing and releasing the core component by reducing the particle size.

[0154] The technical solution for preparing microcapsules of the present invention has at least the following excellent technical effects:

[0155] (1) The preparation methods of the present invention all use non-toxic or low-toxic solvents, the reaction steps are simple, the requirements for equipment are low, the energy consumption is small, the process conditions are simple, and the post-treatment is simple.

[0156] (2) The present invention can endow the grafted product with photo-responsive ability while preparing it. After being irradiated by ultraviolet UV-340 light, the cinnamate derivative will undergo cis-trans isomerization, resulting in a decrease in the particle size and PDI of the microcapsules.

[0157] (3) The present invention can be carried out under neutral conditions with mild reactions.

[0158] (4) The microcapsules prepared by the present invention have novel characteristics and are significantly different from the existing microcapsules in terms of release behavior. When the particle size of the microcapsules decreases, the core components will be extruded and released, achieving the effect of controlled release.

[0159] The present invention will be described in detail below in conjunction with the embodiments and the drawings. However, it should be understood that the embodiments and the drawings are only used for exemplary description of the present invention and cannot constitute any limitation to the protection scope of the present invention. All reasonable transformations and combinations within the scope of the inventive concept of the present invention fall within the protection scope of the present invention.

[0160] Materials and Methods

[0161] Instrument for measuring ultraviolet-visible absorption spectrum: Shimadzu UV-3600i Plus from Japan; Measuring steps or test conditions: Turn on the machine and preheat for 20 min. Dilute the nanoparticle dispersion with deionized water to 0.2 mg / mL and then load it into a quartz cuvette. Set the scanning wavelength to 200 - 1000 nm. Perform a baseline scan using a barium sulfate standard white plate. After calibration is completed, place the sample on the sample side and collect the absorbance spectrum of the sample at 25°C.

[0162] Instrument for dynamic light scattering (DLS) measurement: Malvern Zetasizer Nano ZS90 from the UK; Measuring steps or test conditions: Suck out 1 mL of the upper emulsion and dilute it 5 - 10 times with water; The dilution factor of each sample is the same. Then, drop it into the DLS sample cell and perform DLS tests at 25°C to obtain the average droplet diameter and zeta potential of the emulsion. Each sample is parallel three times, and the results are expressed as arithmetic means.

[0163] Instrument for transmission electron microscopy (TEM) test: FEI Talos F200X G2 from the US; Measuring steps or test conditions: Drop the emulsion on a copper grid and let it dry under a fume hood for 30 minutes, and perform TEM imaging at a voltage of 100 kv.

[0164] Instrument used for scanning electron microscope (SEM) test: ZEISS Sigma 300 from Germany; Measurement steps or test conditions: Directly stick the freeze-dried nanoparticles onto the conductive adhesive, and use the Quorum SC7620 sputter coater to spray gold for 45 s at a current of 10 mA; Subsequently, use SEM to take pictures of the sample morphology. When taking the morphology pictures, the acceleration voltage is 3 kV and the detector is the SE2 secondary electron detector.

[0165] Total antioxidant capacity tests of ABTS and FRAP: Use the total antioxidant capacity detection kit (ABTS method and FRAP method) to evaluate the total antioxidant capacity of the nanoparticles. The specific steps refer to the kit instruction manual. Prepare Trolox solution and solution as the positive control, and draw the standard curve of its concentration vs. antioxidant capacity. The total antioxidant capacity and reductive power of the nanoparticles were determined by ABTS method and FRAP method respectively.

[0166] Determination of DPPH radical scavenging rate: Use the DPPH radical scavenging capacity kit for antioxidant test. The specific steps refer to the kit instruction manual. Set up the measurement tube A1 (containing the nanoparticles to be tested and DPPH solution), the control tube A2 (containing only DPPH solution without sample), and the blank tube A3 (containing the nanoparticles to be tested and solvent). All test tubes were left to stand in the dark at room temperature for 30 min to ensure full reaction. After the reaction, centrifuge to remove the precipitate, and collect the supernatant. Use a spectrophotometer to measure the absorbance values A of the solutions in each tube at a wavelength of 517 nm, corresponding to the measurement tube A1, the control tube A2, and the blank tube A3 respectively. Calculate the scavenging rate of DPPH radicals according to the following formula:

[0167] DPPH scavenging rate (%) = [(A2 + A3) - A1] / A2 × 100%.

[0168] Emulsion appearance photography: Conducted in a DOHO D60 standard light source box with black as the background color, adjusted to a color temperature of 6500 k, and after manual white balance, use the rear camera of the mobile phone for focusing and shooting.

[0169] Instrument used for Fourier transform infrared spectroscopy: Thermo Fisher Scientific Nicolet iS20 from the United States; Measurement steps or test conditions: Mix the sample with potassium bromide, grind it, and then press it into a tablet. Fourier transform infrared spectroscopy is recorded in the range of 4000 - 500 cm -1 with a resolution of 4 cm -1 .

[0170] Instruments used in the confocal laser microscope: Leica STELLARIS 5; Measurement steps or test conditions: Add 10 μL of 1 mg / mL Calcofluor white staining solution and 10 μL of 1 mg / mL Nile red staining solution to 1 mL of the sample solution. After staining for 10 min, take 10 μL of the sample and prepare it on a glass slide. Set the excitation wavelengths to 405 nm and 559 nm, receive the emission at 432 nm and 635 nm, and observe under the confocal laser microscope.

[0171] Contact angle measurement: Measurement steps or test conditions: Place the sample on the Kunshan Shengding SDC350KS contact angle measuring instrument on the liftable platform, perform the sessile drop method test with 2 μL of water droplets, and save the images of the contact between the water droplets and the glass slide at different times. Calculate the contact angle of the sample at the air-water interface using the Laplace-Young equation.

[0172] Instruments used in the ultraviolet spectrophotometer measurement: Shimadzu UV-3600i Plus of Japan. Test steps or test conditions for the release rate of the core component in the microcapsules: Add 10 mL of cyclohexane to a certain mass of freeze-dried microcapsule powder, and use an ultrasonic cell disruptor equipped with 、1 / 8’, 250 μm microtips to extract the core component from the mixture. Subsequently, use the ultraviolet spectrophotometer to record the absorbance of the extract at 236 nm to determine the mass of the lost core component, and thus calculate the loss rate. The formula for calculating the release rate is:

[0173] ,

[0174] ,

[0175] ,

[0176] where m0 is the total mass of limonene added; m1 is the theoretical mass of the microcapsules before freeze-drying; m2 is the actual mass of the microcapsules after freeze-drying, C1 is the determined limonene concentration; C2 is the loading rate before UV irradiation; C3 is the loading rate after UV irradiation. V1 is the volume of cyclohexane added, which is 10 mL in this test.

[0177] Example 1, nanoparticles

[0178] 1. Prepare an aqueous solution of soy protein isolate at 2 wt%, stir it at a speed of 600 r for 2 h, and store it at 4 °C for 12 h. Then place it in a 90 °C water bath for 30 min and quickly cool it to room temperature to obtain a soy protein isolate dispersion.

[0179] 2. Dissolve phenethyl caffeate in 10 mL of ethanol to prepare a 50 mM alcoholic solution. Add anhydrous copper chloride with a final concentration of 0.2 mol% as a catalyst, and then add 680 μL of hydrogen peroxide solution (final concentration 3 wt%) as an oxidant. Stir and oxidize at 25 °C at a speed of 300 r for 10 min to obtain an aqueous alcoholic solution of the quinone-type compound.

[0180] 3. Slowly adjust the pH of the aqueous alcoholic solution of the quinone-type compound to neutral with 0.5 M sodium hydroxide, and then add it to the soy protein isolate dispersion. Use 1 M sodium hydroxide to adjust the mixture to pH 8.5, and stir and react at 35 °C at a speed of 600 r for 3 h. After the reaction, adjust the mixture back to pH 7.0 with 0.5 M hydrochloric acid and separate the insoluble matter. Freeze-dry the obtained clear liquid to obtain nanoparticles.

[0181] The ultraviolet-visible absorption spectrum is as Figure 1 shown. Compared with soy protein isolate (a), the nanoparticles (b) have obvious peaks at 330 nm and 690 nm, indicating that the nanoparticles have successfully reacted with phenethyl caffeate and have obvious ultraviolet and visible light absorption capabilities.

[0182] The DLS test is as Figure 2 shown. The average particle size of the single peak of the nanoparticles before light irradiation is 48 nm, and the PDI is 0.272; the average particle size of the single peak after light irradiation is 22 nm, and the PDI is 0.134. This shows that the nanoparticles have undergone cis-trans isomerization after light irradiation, resulting in a decrease in particle size and a more uniform distribution.

[0183] The ABTS and FRAP tests are as Figure 3 shown in a-b, indicating that the antioxidant effects of 10 mg / mL nanoparticles are equivalent to 1.10 mM and 4.16 mM of Trolox (antioxidant) equivalents respectively, showing strong total antioxidant capacity.

[0184] In addition, the DPPH radical scavenging rate of 10 mg / mL nanoparticles is 62.62%, indicating that they have the ability to scavenge free radicals.

[0185] Example 2. Pickering emulsion of 5 v / v% limonene

[0186] Redissolve the nanoparticles prepared in Example 1 in deionized water to prepare an aqueous solution of 10 mg / mL. Add 5 v / v% of limonene, and then emulsify with a high-speed disperser at a speed of 8000 rpm for 3 min, and store at 4 °C for 12 h to obtain a Pickering emulsion containing 5 v / v% of limonene.

[0187] The TEM test is as Figure 4As shown, a complete emulsion structure can be observed.

[0188] The SEM test is as Figure 5 shown, showing the structure of Pickering emulsion, with nanoparticles adsorbed on the droplet surface.

[0189] The DLS test results are as Figure 6 shown. The average droplet diameter of the emulsion before light irradiation is 411.6 nm, and the PDI is 0.316. The average droplet diameter after light irradiation is 326.9 nm, and the PDI is 0.251.

[0190] The above results indicate that the nanoparticles have a light responsiveness at the emulsion interface. The Pickering emulsion loaded with 5 v / v% limonene has a smaller particle size and a more uniform distribution after light irradiation.

[0191] Example 3. Preparation of Pickering emulsion with 10 v / v% limonene

[0192] The nanoparticles prepared in Example 1 were redissolved in deionized water to prepare an aqueous solution with a concentration of 5 mg / mL. 10 v / v% of limonene was added, and then emulsified with a high-speed disperser at a rotation speed of 8000 rpm for 3 min, and stored at 4 °C for 12 h to obtain a Pickering emulsion.

[0193] The DLS test results are as Figure 7 shown. The average droplet diameter of the emulsion before light irradiation is 386.7 nm, and the PDI is 0.274. The average droplet diameter after light irradiation is 294.1 nm, and the PDI is 0.192.

[0194] The above results indicate that the nanoparticles have a light responsiveness at the emulsion interface. The Pickering emulsion loaded with 10 v / v% limonene has an even smaller particle size and a more uniform distribution after light irradiation.

[0195] Example 4. Preparation of Pickering emulsion with 50 v / v% peppermint essential oil

[0196] The nanoparticles were redissolved in deionized water to prepare an aqueous solution with a concentration of 1 mg / mL. 50 v / v% of peppermint essential oil was added, and then emulsified with a high-speed disperser at a rotation speed of 8000 rpm for 3 min, and stored at 4 °C for 12 h to obtain a Pickering emulsion.

[0197] The DLS test results are as Figure 8 shown. The average droplet diameter of the emulsion before light irradiation is 1415 nm, and the PDI is 0.310. The average droplet diameter after light irradiation is 767.2 nm, and the PDI is 0.116.

[0198] It is shown that the nanoparticles have photoreactivity at the emulsion interface. The Pickering emulsion loaded with 50 v / v% peppermint essential oil has a small particle size and a uniform distribution after illumination.

[0199] The test results of DLS zeta potential are as Figure 9 shown. Before illumination, the zeta potential of the emulsion shows a multi-peak distribution, while after illumination, it shows a single-peak distribution, indicating that illumination changes the adsorption behavior of nanoparticles at the emulsion interface, reorganizes the emulsion interface structure, and makes the zeta potential distribution more uniform.

[0200] Example 5. Preparation of Pickering emulsion with 74 v / v% peppermint essential oil

[0201] The nanoparticles were redissolved in deionized water to prepare an aqueous solution with a concentration of 2 mg / mL. 74 v / v% peppermint essential oil was added, and then emulsified with a high-speed disperser at a speed of 10,000 rpm for 3 min, and stored at 4 °C for 12 h to obtain a high internal phase Pickering emulsion.

[0202] The appearance diagram of the emulsion is as Figure 10 shown. It can be found that obvious oil phase precipitation and color lightening occurred in the emulsion after illumination, indicating that the stability of the high internal phase emulsion is easily affected by the photoreactivity of nanoparticles, and the precipitation of the oil phase is released through the reorganization of the emulsion interface structure.

[0203] Example 6. Preparation of grafted product with phenethyl caffeate as raw material

[0204] Prepare a 25 mL tert-butanol solution of 30 mM phenethyl caffeate. Take 0.5 mol% of anhydrous copper chloride as a catalyst, and then quickly add 1.2 mL of hydrogen peroxide solution (3 wt%) as an oxidant. Stir and oxidize at 25 °C at a speed of 300 r for 15 min to obtain an aqueous alcohol solution of quinone-type compound. Then add carboxymethyl chitosan powder to prepare a solution with a concentration of 0.05 wt%, disperse completely at a speed of 600 r, and then add 30 mL of deionized water to form a co-solvent. Use 1M sodium hydroxide to adjust the pH of the co-solvent to 8.0, stir and react at 40 °C at a speed of 800 r for 6 h. After the reaction, adjust to pH 7.0 with 0.1 M acetic acid, separate the insoluble matter, and freeze-dry the obtained clear liquid to obtain the grafted product.

[0205] The Fourier transform infrared spectra of the grafted product and carboxymethyl chitosan are as Figure 11 shown. The grafted product has an obvious absorption peak at 1740 cm -1 , which is the C=O stretching vibration peak. Compared with carboxymethyl chitosan, the grafted product obtained by reacting with phenethyl caffeate has absorption peaks at 3420 cm -1 , 1461 cm-1 and 1052 cm -1 The characteristic peaks all showed varying degrees of weakening and disappearance, respectively belonging to the stretching vibration of -NH2, the bending vibration of N-H, and the stretching vibration of C-O-C. This indicates that phenethyl caffeate has undergone amino crosslinking with carboxymethyl chitosan. In addition, the peak intensities of -CH2 and -CH at 2923 cm -1 and 2853 cm -1 increased significantly, further proving the formation of the grafted product.

[0206] ABTS and FRAP tests, as shown in Figure 12 a-b below, indicate that the antioxidant effects of the 0.15 wt% grafted product are equivalent to 1.20 mM and 4.06 mM of Trolox equivalents respectively, showing strong total antioxidant capacity.

[0207] In addition, the DPPH radical scavenging rate of the 0.15 wt% grafted product is 67.17%, indicating its ability to scavenge free radicals.

[0208] Example 7. Preparation of a grafted product using benzyl caffeate as a raw material

[0209] Prepare a 25 mL tert-butanol solution of 50 mM benzyl caffeate. Take 1 mol% of anhydrous copper chloride as a catalyst, and then quickly add 0.8 mL of hydrogen peroxide solution (3 wt%) as an oxidant. Stir and oxidize at 25 °C at a rotation speed of 300 r for 15 min to obtain an aqueous alcohol solution of the quinone-type compound. Then add carboxymethyl chitosan powder to prepare a 0.2 wt% solution, disperse it completely at a rotation speed of 600 r, and then add 30 mL of deionized water to form a co-solvent. Use 1 M sodium hydroxide to adjust the pH of the co-solvent to 8.0, and stir and react at 40 °C at a rotation speed of 800 r for 6 h. After the reaction, adjust the pH to 7.0 with 0.1 M acetic acid, separate the insoluble matter, and freeze-dry the obtained clear liquid to obtain the grafted product.

[0210] Redissolve the grafted product in the co-solvent to prepare a 0.05 wt% solution, add 10 v / v% of peppermint essential oil, use deionized water as the dialysis solution, the molecular weight cut-off of the dialysis bag is 3500 Da, the dialysis time is 6 h, and change the water every 3 h to obtain microcapsules.

[0211] The confocal laser scanning microscopy image of the microcapsules is as shown in Figure 13As shown, (a) is the superimposed diagram of the core-shell structure, (b) is the core component stained with Nile red, and (c) is the shell structure stained with Calcofluor white, demonstrating that the core component was successfully encapsulated in the shell structure to form microcapsules. The contact angle of the graft at the air-water interface is ≥60°, and the average particle size of the microcapsules is 500 nm - 1.5 μm.

[0212] Example 8: Preparation of a graft containing n-octyl caffeate as a raw material

[0213] Prepare a 25 mL tert-butanol solution of 10 mM n-octyl caffeate. Take 0.2 mol% of anhydrous copper chloride as a catalyst, and then quickly add 1 mL of hydrogen peroxide solution (3 wt%) as an oxidant. Stir and oxidize at 25 °C at a rotation speed of 300 r for 15 min to obtain an aqueous alcohol solution of the quinone-type compound. Then add carboxymethyl chitosan powder to it and prepare a 0.4 wt% solution. Disperse it completely at a rotation speed of 600 r, and then add 30 mL of deionized water to form a co-solvent. Use 1 M sodium hydroxide to adjust the pH of the co-solvent to 8.0, and stir and react at 40 °C at a rotation speed of 800 r for 6 h. After the reaction, adjust to pH 7.0 with 0.1 M acetic acid, separate the insoluble matter, and freeze-dry the obtained clear liquid to obtain the graft.

[0214] Redissolve the graft in the co-solvent and prepare a 0.2 wt% solution. Add 5 v / v% of limonene. Use deionized water as the dialysis solution. The molecular weight cut-off of the dialysis bag is 3500 Da, and the dialysis time is 12 h. Change the water every 3 h to obtain microcapsules.

[0215] The air-water contact angle of the graft prepared using 10 mM n-octyl caffeate is compared with that of carboxymethyl chitosan as Figure 14 shown. The contact angle of carboxymethyl chitosan is 41.655°, while the contact angle of the graft is 63.711°, indicating that the carboxymethyl chitosan containing cinnamate groups has enhanced hydrophobicity and microcapsules are successfully formed.

[0216] DLS test as Figure 15 shown. The average particle size of the microcapsules before light irradiation is 816 nm, and the PDI is 0.403; the average particle size after light irradiation is 663 nm, and the PDI is 0.272. This shows that the microcapsules have light responsiveness, and the microcapsules loaded with 5 v / v% limonene have a smaller particle size and a more uniform distribution after light irradiation.

[0217] Example 9: Preparation of a graft containing caffeic acid-1,1-dimethylallyl ester as a raw material

[0218] Prepare a 25 mL tert-butanol solution of 20 mM caffeic acid-1,1-dimethylallyl ester. Take 0.2 mol% of anhydrous copper chloride as a catalyst, and then quickly add 1 mL of hydrogen peroxide solution (3 wt%) as an oxidant. Stir and oxidize at 25 °C at a speed of 300 r for 15 min to obtain an aqueous alcohol solution of a quinone-type compound. Then add carboxymethyl chitosan powder to it to prepare a 0.4 wt% solution, disperse it completely at a speed of 600 r, and then add 30 mL of deionized water to form a co-solvent. Use 1 M sodium hydroxide to adjust the pH of the co-solvent to 8.0, and stir and react at 40 °C at a speed of 800 r for 6 h. After the reaction, adjust to pH 7.0 with 0.1 M acetic acid, separate the insoluble matter, and freeze-dry the obtained clear liquid to obtain a grafted product. Dissolve the grafted product in the co-solvent again to prepare a 0.1 wt% solution, add 5 v / v% of limonene, use deionized water as the dialysis solution, the molecular weight cut-off of the dialysis bag is 3500 Da, and the dialysis time is 12 h. Change the water every 3 h to obtain microcapsules.

[0219] The air-water contact angle of the grafted product prepared using 20 mM caffeic acid-1,1-dimethylallyl ester was compared with that of carboxymethyl chitosan. Figure 16 As shown, the contact angle of carboxymethyl chitosan was 41.655°, while the contact angle of the grafted product was 73.337°, indicating that the hydrophobicity of carboxymethyl chitosan containing cinnamate groups was enhanced and microcapsules were successfully formed.

[0220] The DLS test was as Figure 17 shown. The average particle size of the microcapsules before light irradiation was 712 nm, and the PDI was 0.226; the average particle size after light irradiation was 459 nm, and the PDI was 0.169. This shows that the microcapsules have light responsiveness, and the microcapsules loaded with 5 v / v% limonene have a smaller particle size and a more uniform distribution after light irradiation.

[0221] The graph of the release amount of microcapsules varying with the light irradiation time was as Figure 18 shown. The release performance of the two kinds of microcapsules after light irradiation for limonene was significantly better than that of the control group. At 2 h of irradiation, the two kinds of microcapsules showed higher release efficiency, which was 10% and 15% higher than that of the control group respectively. As the irradiation time was extended to 4 h, this trend further expanded, and the release amounts of the two kinds of microcapsules after light irradiation were 20% higher than that of the control group. After continuous irradiation for 6 h, the release amounts of the two kinds of microcapsules for limonene both stabilized at about 39%, showing good light responsiveness and light-controlled release ability. At this time, the release amount of the control group was 20%, which was lower than that of the microcapsules in the light-irradiated group.

[0222] The results show that the microcapsules have a promoting effect on the release of the core components under UV-340 irradiation.

[0223] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention shall be subject to the appended claims.

Claims

1. A method for preparing a light-responsive antioxidant preparation, characterized in that, The light-responsive antioxidant preparation is a Pickering emulsion, and the method includes: A: Dispersing a biopolymer in water at a mass concentration of 1-10 wt%, mixing well, incubating at 4±2 °C and then at 90±10 °C, and quickly cooling to room temperature to obtain a biopolymer dispersion; the biopolymer is soy protein isolate; B: Dissolving a cinnamate derivative in ethanol to form an alcohol solution with a cinnamate derivative concentration of 20-80 mM, using 0.05-2 mol% copper ions as a catalyst and 3±2 wt% hydrogen peroxide as an oxidant, mixing and oxidizing at 10-30 °C to obtain an aqueous-alcohol solution of a quinone-type compound; the cinnamate derivative is phenethyl caffeate; C: Adjusting the pH of the aqueous-alcohol solution of the quinone-type compound to neutral, mixing it with the biopolymer dispersion, adjusting the pH of the mixture to 8.5±1 and mixing well, reacting for 2-8 h; adjusting the reaction product to neutral and freeze-drying to obtain nanoparticles; D: Dissolving 0.5-20 mg / mL of the nanoparticles in water, adding an aromatic compound, and emulsifying to obtain the Pickering emulsion; the aromatic compound includes limonene or peppermint essential oil; the volume fraction of the aromatic compound is 3-80 v / v%.

2. The method according to claim 1, wherein In C, after adjusting the reaction product to neutral, it further includes: removing insoluble substances and harvesting the supernatant for freeze-drying.

3. The method according to claim 1, characterized in that, In D, 1-15 mg / mL of the nanoparticles are dissolved in water.

4. A method for preparing a light-responsive antioxidant preparation, characterized in that, The light-responsive antioxidant preparation is a microcapsule, and the method includes: A': Dissolving a cinnamate derivative in tert-butanol to form an alcohol solution with a cinnamate derivative concentration of 5-80 mM, using 0.05-2 mol% copper ions as a catalyst and hydrogen peroxide as an oxidant, mixing and oxidizing at 10-30 °C to obtain an aqueous-alcohol solution of a quinone-type compound; the cinnamate derivative is phenethyl caffeate, benzyl caffeate, n-octyl caffeate or 1,1-dimethylallyl caffeate; the molar ratio of the cinnamate derivative to hydrogen peroxide is 1:0.8-3; B': Dispersing a biopolymer in the aqueous-alcohol solution of the quinone-type compound, and then adding an equal volume of water to form a co-solvent; the biopolymer is carboxymethyl chitosan, and its mass concentration is 0.1-2 wt%; C': Adjusting the pH of the mixture to 8.0±0.6, mixing well at 30-45 °C, reacting for 2-8 h; adjusting the reaction product to neutral and freeze-drying to obtain a grafted product; D': Dissolving 0.02-0.8 wt% of the grafted product in water, adding an aromatic compound, and retaining the part with a molecular weight greater than 3500 Da by dialysis to obtain a microcapsule with light-responsive properties; the aromatic compound includes limonene or peppermint essential oil; the volume fraction of the aromatic compound is 1-20 v / v%.

5. The method according to claim 4, wherein In D', the mass concentration of the grafted product is 0.05-0.2 wt%.

6. The method according to claim 4, wherein In D', water is used as the dialysis solution in the dialysis method.

7. The method according to claim 1 or 4, characterized in that, The copper ions include copper ions from copper chloride or copper sulfate.

8. The method according to claim 1 or 4, characterized in that, The quinone-type compound includes: a semiquinone compound or an o-benzoquinone compound.

9. A light-responsive antioxidant preparation, which is obtained by the method according to any one of claims 1 to 7.

10. Use of the light-responsive antioxidant preparation according to claim 9 for the preparation of a cosmetic, wherein the aromatic compound can be controlled-release.

11. The application according to claim 10, characterized in that, The cosmetic is a skin care product.

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