Sunscreen microcapsule of starch-based wall material as well as preparation method and application of sunscreen microcapsule

Abstract

The invention discloses a sunscreen microcapsule of a starch-based wall material as well as a preparation method and application of the sunscreen microcapsule, and the method comprises the following steps: emulsifying an oil-soluble chemical sunscreen agent in a synergistic manner by using naturally-sourced starch nanoparticles and polyphenol to obtain an oil-in-water-soluble chemical sunscreen agent Pickering emulsion; metal ions are introduced into the emulsion, the pH of the system is adjusted, and after the metal ions and polyphenol form a network structure, the sunscreen microcapsule is obtained through centrifugal washing. The preparation method of the sunscreen microcapsule provided by the invention has the advantages of simple steps, high controllability, low cost and environmental friendliness. The sunscreen microcapsule prepared by the method has excellent light stability, biocompatibility and biological adhesiveness.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemicals, and in particular relates to a sunscreen microcapsule with a starch-based wall material, and a preparation method and application thereof. Background Art

[0002] Long-term exposure to ultraviolet rays can cause tanning, sunburn, aging and even skin cancer. Ultraviolet radiation is mainly divided into UVA band (320-400nm) and UVB band (280-320nm). Ultraviolet rays in the UVA band can reach the dermis of human skin, damage cell DNA, cause skin aging and even skin cancer. Ultraviolet rays in the UVB band can cause skin allergies, tanning and sunburn. Sunscreens reduce the damage to the skin by reflecting, scattering or absorbing ultraviolet rays. Physical sunscreens, such as titanium dioxide and zinc oxide, feel greasy and heavy on the skin, may clog pores, and are prone to photocatalytic reactions to produce ROS and damage the skin. Chemical sunscreens are more popular with consumers because of their refreshing and fitting texture, easy application and high transparency. Chemical sunscreens are generally aromatic small molecules, such as avobenzone, cinnamate and salicylate. They can penetrate into the dermis and even enter the blood circulation; in addition, they have poor photostability and are easily decomposed under ultraviolet rays, resulting in poor sun protection performance. At the same time, the free radicals produced will affect the stability of other ingredients in the formula and may even directly damage the skin.

[0003] Microencapsulation technology can improve the above-mentioned shortcomings of chemical sunscreens to a certain extent, but the existing methods for preparing sunscreen microcapsules are complicated, poorly controllable, costly, and inevitably use harmful chemical reagents; at the same time, most sunscreen microcapsules use synthetic polymers or inorganic materials as wall materials, which have poor biocompatibility, are not environmentally friendly, and do not meet the requirements of sustainable development.

[0004] Therefore, developing a simple, controllable and environmentally friendly method to prepare sunscreen microcapsules with high photostability, good biocompatibility and bioadhesion has great research significance and economic value. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing sunscreen microcapsules with starch-based wall materials.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for preparing sunscreen microcapsules with starch-based wall materials, comprising:

[0009] preparing starch nanoparticle dispersion and polyphenol solution respectively;

[0010] The starch nanoparticle dispersion, the polyphenol solution and the oil-soluble chemical sunscreen are mixed and emulsified to obtain a water-in-oil-soluble chemical sunscreen Pickering emulsion;

[0011] Metal ions are introduced into the obtained emulsion, and the pH value of the system is adjusted to promote the metal ions and polyphenols to form a network structure, and sunscreen microcapsules are obtained through centrifugal washing.

[0012] As a preferred embodiment of the preparation method of the present invention, the starch nanoparticles are derived from one or more of corn, rice, potato, oat and barley.

[0013] As a preferred embodiment of the preparation method of the present invention, the polyphenols are derived from gallnut, chestnut, quebracho, green tea and witch hazel.

[0014] As a preferred embodiment of the preparation method of the present invention, the preparation of starch nanoparticle dispersion comprises:

[0015] Weigh starch nanoparticle powder and disperse it in deionized water, adjust the pH of the aqueous phase to 3-8, and the concentration thereof is 0.1-5 w / v% in g / mL.

[0016] As a preferred embodiment of the preparation method of the present invention, the preparation of the polyphenol solution comprises:

[0017] Weigh polyphenol powder and dissolve it in deionized water, and adjust the pH of the solution to 3-8 to obtain a polyphenol solution with a concentration of 0.01-10 w / v% in g / mL.

[0018] As a preferred embodiment of the preparation method of the present invention, the oil-soluble chemical sunscreen includes one or more of ethylhexyl methoxycinnamate, ethylhexyl salicylate, homosalate, octocrylene, dimethyl PABA ethylhexyl ester, avobenzone, and diethylaminohydroxybenzoyl hexyl benzoate.

[0019] As a preferred embodiment of the preparation method of the present invention, the mass ratio of the starch nanoparticles to the polyphenols is 10:1 to 1:2;

[0020] The emulsification method includes one or more of vortexing, homogenization, and ultrasound, and the emulsification time is 0.5 to 10 minutes;

[0021] The volume fraction of the oil phase is 5 to 80 v / v%.

[0022] As a preferred embodiment of the preparation method of the present invention, the metal ion is one or more of divalent copper ion, divalent zinc ion, trivalent iron ion, trivalent aluminum ion and tetravalent zirconium ion; the molar ratio of the metal ion to the polyphenol is 1:4 to 4:1, and the pH of the system is 3 to 9;

[0023] The centrifugal speed is 3000-15000 rpm, the centrifugal time is 1-10 minutes, and the number of centrifugal times is 2-8 times.

[0024] Another object of the present invention is to overcome the deficiencies in the prior art and provide a method for using a sunscreen microcapsule with a starch-based wall material in the preparation of cosmetics.

[0025] Another object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a biocompatible sunscreen by using a microcapsule having a starch-based wall material, comprising:

[0026] The starch nanoparticle dispersion, the polyphenol solution and the oil-soluble chemical sunscreen component are mixed and emulsified to obtain a water-in-oil-soluble chemical sunscreen Pickering emulsion;

[0027] Metal ions are introduced into the obtained emulsion, and the pH value of the system is adjusted to promote the metal ions and polyphenols to form a network structure, and a biocompatible sunscreen is obtained through centrifugal washing.

[0028] Beneficial effects of the present invention:

[0029] (1) The present invention discloses a starch-based wall material microcapsule and a preparation method thereof, and uses the same in the preparation of a biocompatible sunscreen. The preparation method has a simple process, high controllability, low cost and is environmentally friendly, overcoming the defects of the prior art sunscreen microcapsule preparation method, which has a complex process, poor controllability, high cost, and inevitably uses harmful chemical reagents, has poor biocompatibility and is environmentally unfriendly.

[0030] (2) The present invention uses naturally derived starch nanoparticles and a metal-polyphenol network with good biocompatibility and bioadhesion as wall materials, giving the sunscreen microcapsules excellent biocompatibility, bioadhesion and photostability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0032] Figure 1 This is an optical microscope image of the sunscreen microcapsules prepared in Example 1.

[0033] Figure 2 This is the appearance of the sunscreen microcapsule aqueous dispersion prepared in Example 1.

[0034] Figure 3 These are the in vitro SPF test values ​​of the microcapsule sunscreen prepared in Example 1 and the cream without sunscreen ingredients.

[0035] Figure 4 The sunscreen retention rate of the sunscreen microcapsule aqueous dispersion prepared in Example 1 and the unencapsulated chemical sunscreen after 8 hours of ultraviolet irradiation.

[0036] Figure 5 This is a laser confocal test image of the sunscreen microcapsule / physiological saline dispersion prepared in Example 1 and the unencapsulated chemical sunscreen after penetration into pig skin for 12 hours.

[0037] Figure 6 This is the SEM image of the microcapsules prepared in Example 2.

[0038] Figure 7 This is the FT-IR graph of the microcapsules prepared in Example 2. DETAILED DESCRIPTION

[0039] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0040] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0041] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0042] If no specific conditions are specified in the examples of the present invention, the examples are carried out under conventional conditions; the raw materials, reagents, etc. used without specifying the manufacturers are all conventional reagents, methods and equipment in the technical field.

[0043] Example 1

[0044] (1) 8 g of starch nanoparticles were dispersed in 400 mL of deionized water and the pH was adjusted to 5 to obtain a 2 w / v % starch nanoparticle dispersion.

[0045] (2) Dissolve 4 g of polyphenol powder in 400 mL of deionized water and adjust the pH to 5 to obtain a 1 w / v% polyphenol solution.

[0046] (3) 3 mL of the starch nanoparticle dispersion prepared in step (1) and 3 mL of the polyphenol solution prepared in step (2) were mixed, and 0.6 mL of ethylhexyl methoxycinnamate was added. The mixture was ultrasonically emulsified at a power of 400 W for 5 minutes to obtain a Pickering emulsion template.

[0047] (4) Add 6 mL of 3 mM ferric chloride solution to the Pickering emulsion template in step (3), adjust the system pH to 8, and finally centrifuge and wash three times with deionized water at a centrifugal speed of 8000 rpm for 5 minutes to obtain sunscreen microcapsules with starch-based wall materials. Disperse the sunscreen microcapsules in deionized water to make the total volume of the sunscreen microcapsule aqueous dispersion 6 mL.

[0048] (5) The sunscreen microcapsules obtained in step (4) are mixed with Dabao vitamin E milk without sunscreen ingredients to obtain a sunscreen cream, wherein the content of the sunscreen microcapsules is 10 wt %.

[0049] Figure 1 This is an optical microscope photograph of the aqueous dispersion of the sunscreen microcapsules in Example 1. It can be clearly observed that the sunscreen microcapsules have a good spherical morphology and an average particle size of about 1 μm, indicating that the method can control the size of the microcapsules through emulsification conditions and system composition.

[0050] Figure 2 This is a photograph of the appearance of the sunscreen microcapsule aqueous dispersion in Example 1, indicating that the sunscreen microcapsule has good water dispersibility.

[0051] SPF Test:

[0052] According to ISO 24443:2012 standard method, the Dabao vitamin E lotion and the microcapsule sunscreen obtained in step (5) were tested using an ultraviolet transmittance analyzer (UV-2000S).

[0053] Figure 3The in vitro SPF test values ​​of the microcapsule sunscreen prepared in Example 1 and the Dabao vitamin E lotion without sunscreen ingredients show that the microcapsule sunscreen has good sunscreen performance compared to the Dabao vitamin E lotion.

[0054] Light stability test:

[0055] The microcapsules prepared in step (4) of Example 1 were dispersed in anhydrous ethanol, vortexed and centrifuged, and the ultraviolet absorbance of the supernatant at 311 nm was measured and recorded as A1;

[0056] Unencapsulated chemical sunscreen ethylhexyl methoxycinnamate was dispersed in anhydrous ethanol, vortexed and centrifuged, and the ultraviolet absorbance of the supernatant at 311 nm was measured and recorded as A2.

[0057] The microcapsules prepared in step (4) of Example 1 and the unencapsulated chemical sunscreen were irradiated with an 800 W ultraviolet lamp. After 8 hours of irradiation, the above samples were dispersed in anhydrous ethanol, vortexed and centrifuged, and the absorbance of the supernatants of the two samples at 311 nm was measured and recorded as A3 and A4, respectively.

[0058] The retention rate of unencapsulated chemical sunscreen (%) = A4 / A2 x 100%.

[0059] The sunscreen agent retention rate of the starch-based wall material sunscreen microcapsules (%) = A3 / A1×100%.

[0060] Figure 4 The sunscreen retention rate of the sunscreen microcapsule aqueous dispersion prepared in Example 1, the unencapsulated chemical sunscreen and the Pickering emulsion prepared in Comparative Example 3 after 8 hours of irradiation with an 800W UV lamp. The unencapsulated chemical sunscreen has a retention rate of only about 10%, the retention rate of the chemical sunscreen in the Pickering emulsion stabilized by starch nanoparticles alone is 25%, and the retention rate of the chemical sunscreen in the microcapsule is close to 60%, which is about 5 times and 2 times of the former. It is proved that the sunscreen microcapsule effectively improves the photostability of the encapsulated chemical sunscreen.

[0061] Laser confocal test:

[0062] Skin penetration was simulated using the Franz diffusion model;

[0063] The microcapsules prepared in step (4) of Example 1 were dispersed in 600 mL of PBS buffer solution to obtain a PBS dispersion of sunscreen microcapsules.

[0064] The pig skin is sandwiched between the donor pool and the receiving pool of the Franz diffusion cell, the diffusion liquids are the PBS dispersion of the sunscreen microcapsules and the unencapsulated chemical sunscreen agent ethylhexyl methoxycinnamate, and the receiving liquid is PBS buffer;

[0065] The Franz cell was placed in a 37°C water bath, and the pigskin was taken out after 12 hours. The pigskin surface was rinsed with 20 mL of PBS buffer and sliced ​​into thin slices at -20°C using a freezing microtome. The penetration of microcapsules and unencapsulated chemical sunscreens in pigskin was observed under a laser confocal scanning microscope.

[0066] Figure 5 This is a laser confocal test image of the sunscreen microcapsules prepared in Example 1 and the unencapsulated chemical sunscreen after being retained on the pig skin surface for 12 hours; Figure 5 It can be seen that the sunscreen microcapsules mainly reside on the surface of pig skin. Even after multiple rinsing with PBS buffer, there are still sunscreen microcapsules adhered to the pig skin surface, and the unencapsulated chemical sunscreens have penetrated into the dermis of the pig skin, which proves the excellent bioadhesion of the sunscreen microcapsules. At the same time, the wall material of the microcapsules can prevent the chemical sunscreens from direct contact with the skin, enhancing its safety in use.

[0067] Example 2

[0068] (1) 6 g of starch nanoparticles were dispersed in 300 mL of deionized water and the pH was adjusted to 5 to obtain a 2 w / v % starch nanoparticle dispersion.

[0069] (2) Dissolve 1 g of polyphenol powder in 100 mL of deionized water and adjust the pH to 5 to obtain a 1 w / v% polyphenol solution.

[0070] (3) 1.5 mL of the starch nanoparticle dispersion prepared in step (1) and 1.5 mL of the polyphenol solution prepared in step (2) were mixed, and 0.6 mL of n-hexane was added. The mixture was ultrasonically emulsified at a power of 500 W for 4 minutes to obtain a Pickering emulsion template.

[0071] (4) Add 3 mL of 3.2 mM ferric chloride solution to the Pickering emulsion template in step (3), adjust the pH of the system to 7.4, and finally wash it by centrifugation with deionized water for 3 times at a centrifugal speed of 4000 rpm for 6 minutes to obtain microcapsules.

[0072] Volatile n-hexane was selected as the core material to replace chemical sunscreens to further confirm the formation and composition of the microcapsule wall material.

[0073] Figure 6 This is the SEM image of the microcapsules in Example 2. The collapsed morphology of the sample confirms the formation of the microcapsule wall material and its hollow structure.

[0074] Figure 7FT-IR image of the microcapsule in Example 2 shows the presence of characteristic absorption peaks of starch nanoparticles and polyphenols in the microcapsule; in addition, the intensity of the characteristic peak of C-OH in the polyphenols is significantly reduced, confirming the formation of the metal-polyphenol network. This proves that the main component of the wall material of the microcapsule is starch nanoparticles / metal-polyphenol network.

[0075] Example 3

[0076] (1) 60 g of starch nanoparticles were dispersed in 3000 mL of deionized water and the pH was adjusted to 5 to obtain a 2 w / v % starch nanoparticle dispersion.

[0077] (2) Dissolve 1 g of polyphenol powder in 100 mL of deionized water and adjust the pH to 5 to obtain a 1 w / v% polyphenol solution.

[0078] (3) 2 mL of the starch nanoparticle dispersion prepared in step (1) and 2 mL of the polyphenol solution prepared in step (2) were mixed and dissolved, and 0.4 mL of ethylhexyl methoxycinnamate was added. The mixture was ultrasonically emulsified at a power of 520 W for 4 minutes to obtain a Pickering emulsion template.

[0079] (4) Add 4 mL of 5.5 mM ferric chloride solution to the Pickering emulsion template in step (3), adjust the system pH to 9, and finally centrifuge and wash 4 times with deionized water at a centrifugal speed of 9000 rpm for 7 minutes to obtain sunscreen microcapsules. The sunscreen microcapsules are dispersed in deionized water to make the total volume of the sunscreen microcapsule aqueous dispersion 4 mL.

[0080] (5) The sunscreen microcapsules obtained in step (4) are mixed with a certain amount of Dabao vitamin E milk without sunscreen ingredients to obtain a microcapsule sunscreen cream with a sunscreen content of 10 wt %.

[0081] The same microcapsule preparation method, optical microscope photograph, appearance of microcapsule aqueous dispersion, SPF test, photostability test, and laser confocal test as those in Example 1 were used.

[0082] The results were Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 Basically the same.

[0083] Example 4

[0084] (1) 2 g of starch nanoparticles were dispersed in 100 mL of deionized water and the pH was adjusted to 5 to obtain a 2 w / v % starch nanoparticle dispersion.

[0085] (2) Dissolve 5 g of polyphenol powder in 500 mL of deionized water and adjust the pH to 5 to obtain a 1 w / v% polyphenol solution.

[0086] (3) 2.5 mL of the starch nanoparticle dispersion prepared in step (1) and 2.5 mL of the polyphenol solution prepared in step (2) were mixed, and 1 mL of n-hexane was added. The mixture was ultrasonically emulsified at a power of 390 W for 6 minutes to obtain a Pickering emulsion template.

[0087] (4) Add 5 mL of 6.7 mM ferric chloride solution to the Pickering emulsion template in step (3), adjust the pH of the system to 7.7, and finally wash it by centrifugation with deionized water for 3 times at a centrifugal speed of 4000 rpm for 6 minutes to obtain microcapsules.

[0088] The same microcapsule preparation method, SEM images, and FT-IR images were used as in Example 2. Figure 6 , Figure 7 Basically the same.

[0089] Example 5

[0090] (1) 3 g of starch nanoparticles were dispersed in 150 mL of deionized water and the pH was adjusted to 5 to obtain a 2 w / v % starch nanoparticle dispersion.

[0091] (2) Dissolve 3 g of polyphenol powder in 300 mL of deionized water and adjust the pH to 5 to obtain a 1 w / v% polyphenol solution.

[0092] (3) 4 mL of the starch nanoparticle dispersion prepared in step (1) and 4 mL of the polyphenol solution prepared in step (2) were mixed and dissolved, and then 0.8 mL of ethylhexyl methoxycinnamate was added, and ultrasonic emulsification was performed at a power of 450 W for 5 minutes to obtain a Pickering emulsion.

[0093] (4) Add 8 mL of 3.5 mM ferric chloride solution to the Pickering emulsion template in step (3), adjust the system pH to 7, and finally centrifuge and wash 4 times with deionized water at a centrifugal speed of 9000 rpm for 7 minutes to obtain sunscreen microcapsules. The sunscreen microcapsules are dispersed in deionized water to make the total volume of the sunscreen microcapsule aqueous dispersion 8 mL.

[0094] (5) The sunscreen microcapsules obtained in step (4) are mixed with a certain amount of Dabao vitamin E milk without sunscreen ingredients to obtain a microcapsule sunscreen cream with a sunscreen content of 10 wt %.

[0095] The same microcapsule preparation method, optical microscope photos, microcapsule aqueous dispersion appearance, SPF test, photostability test, and laser confocal test were used as in Example 1. The results were Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 Basically the same.

[0096] Example 6

[0097] (1) 0.7 g of starch nanoparticles was dispersed in 35 mL of deionized water and the pH was adjusted to 5 to obtain a 2 w / v % starch nanoparticle dispersion.

[0098] (2) Dissolve 0.3 g of polyphenol powder in 30 mL of deionized water and adjust the pH to 5 to obtain a 1 w / v% polyphenol solution.

[0099] (3) 3.5 mL of the starch nanoparticle dispersion prepared in step (1) and 3.5 mL of the polyphenol solution prepared in step (2) were mixed, and 0.7 mL of ethylhexyl methoxycinnamate was added. The mixture was ultrasonically emulsified at a power of 420 W for 4.5 minutes to obtain a Pickering emulsion template.

[0100] (4) Add 8 mL of 5 mM ferric chloride solution to the Pickering emulsion template in step (3), adjust the system pH to 8.5, and finally centrifuge and wash 4 times with deionized water at a centrifugal speed of 9000 rpm for 7 minutes to obtain sunscreen microcapsules. The sunscreen microcapsules are dispersed in deionized water, and the total volume of the sunscreen microcapsule aqueous dispersion is 7 mL.

[0101] (5) The sunscreen microcapsules obtained in step (4) are mixed with a certain amount of Dabao vitamin E milk without sunscreen ingredients to obtain a microcapsule sunscreen cream with a sunscreen content of 10 wt %.

[0102] The same microcapsule preparation method, optical microscope photos, microcapsule aqueous dispersion appearance, SPF test, photostability test, and laser confocal test were used as in Example 1. The results were Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 Basically the same

[0103] Comparative Example 1

[0104] (1) 1.5 g of starch nanoparticles were dispersed in 300 mL of deionized water and the pH was adjusted to 5 to obtain a 2 w / v % starch nanoparticle dispersion.

[0105] (2) Dissolve 2 g of polyphenol powder in 200 mL of deionized water and adjust the pH to 5 to obtain a 1 w / v% polyphenol solution.

[0106] (3) 4 mL of the starch nanoparticle dispersion prepared in step (1) and 4 mL of the polyphenol solution prepared in step (2) were mixed, and then 0.8 mL of octocrylene homosalate was added, and ultrasonic emulsification was performed at a power of 480 W for 4 minutes to obtain a Pickering emulsion template.

[0107] The emulsion template has poor stability and oil leakage, and is not suitable for preparing sunscreen microcapsules.

[0108] Comparative Example 2

[0109] (1) 0.9 g of starch nanoparticles was dispersed in 45 mL of deionized water and the pH was adjusted to 5 to obtain a 2 w / v % starch nanoparticle dispersion.

[0110] (2) Dissolve 0.7 g of polyphenol powder in 70 mL of deionized water and adjust the pH to 5 to obtain a 1 w / v% polyphenol solution.

[0111] (3) 1.5 mL of the starch nanoparticle dispersion prepared in step (1) and 1.5 mL of the polyphenol solution prepared in step (2) were mixed, and 7 mL of ethylhexyl methoxycinnamate was added. The mixture was ultrasonically emulsified at a power of 470 W for 5 minutes to obtain a Pickering emulsion template.

[0112] (4) Add 3 mL of 5.9 mM ferric chloride solution to the Pickering emulsion template in step (3) and adjust the pH of the system to 7.5.

[0113] The Pickering emulsion template prepared in Comparative Example 2 is in a gel state with poor fluidity. The ferric chloride solution is difficult to disperse in the aqueous phase of the emulsion, and cannot fully form a metal-polyphenol network with the polyphenol at the oil-water interface, and cannot form a microcapsule structure.

[0114] Comparative Example 3

[0115] (1) 3 g of starch nanoparticles were dispersed in 300 mL of deionized water and the pH was adjusted to 5 to obtain a 1 w / v% starch nanoparticle dispersion.

[0116] (2) 6 mL of the starch nanoparticle dispersion prepared in step (1) was mixed with 0.6 mL of ethylhexyl methoxycinnamate, and ultrasonically emulsified at a power of 400 W for 5 minutes to obtain a Pickering emulsion template.

[0117] (3) The Pickering emulsion prepared in step (2) is dispersed in anhydrous ethanol, and its ultraviolet absorbance at 311 nm is measured and recorded as A4.

[0118] The Pickering emulsion prepared in step (2) was irradiated with an 800 W ultraviolet lamp. After irradiation for 8 hours, the emulsion was dispersed in anhydrous ethanol, vortexed and centrifuged, and the absorbance of the supernatant at 311 nm was measured and recorded as A5.

[0119] The retention rate of chemical sunscreen in Pickering emulsion stabilized by starch nanoparticles (%) = A4 / A5×100%.

[0120] The invention discloses a starch-based wall material microcapsule and a preparation method thereof, and the microcapsule is applied to prepare a sunscreen with biocompatibility. The preparation method has simple process, high controllability, low cost and is environmentally friendly, and overcomes the defects of the sunscreen microcapsule preparation method in the prior art, such as complex process, poor controllability, high cost, inevitable use of harmful chemical reagents, poor biocompatibility and environmental unfriendliness. The invention uses naturally derived starch nanoparticles and a metal-polyphenol network with good biocompatibility and bioadhesion as wall materials, and endows the sunscreen microcapsule with excellent biocompatibility, bioadhesion and light stability.

[0121] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the present invention.

Claims

1. A method for preparing sunscreen microcapsules with starch-based wall materials, characterized in that: include, preparing starch nanoparticle dispersion and polyphenol solution respectively; The starch nanoparticle dispersion, the polyphenol solution and the oil-soluble chemical sunscreen are mixed and emulsified to obtain a water-in-oil-soluble chemical sunscreen Pickering emulsion; Metal ions are introduced into the obtained emulsion, and the pH value of the system is adjusted to promote the metal ions and polyphenols to form a network structure, and sunscreen microcapsules are obtained through centrifugal washing.

2. The preparation method according to claim 1, characterized in that: The starch nanoparticles are derived from one or more of corn, rice, potato, oat and barley.

3. The preparation method according to claim 1 or 2, characterized in that: The polyphenols are derived from gallnut, chestnut, quebracho, green tea, and witch hazel.

4. The preparation method according to claim 3, characterized in that: The method for preparing the starch nanoparticle dispersion comprises: Weigh starch nanoparticle powder and disperse it in deionized water, adjust the pH of the aqueous phase to 3-8, and the concentration thereof is 0.1-5 w / v% in g / mL.

5. The preparation method according to claim 4, characterized in that: The preparation of the polyphenol solution comprises: Weigh polyphenol powder and dissolve it in deionized water, and adjust the pH of the solution to 3-8 to obtain a polyphenol solution with a concentration of 0.01-10 w / v% in g / mL.

6. The preparation method according to claim 5, characterized in that: The oil-soluble chemical sunscreen includes one or more of ethylhexyl methoxycinnamate, ethylhexyl salicylate, homosalate, octocrylene, dimethyl PABA ethylhexyl ester, avobenzone, and diethylaminohydroxybenzoyl hexyl benzoate.

7. The preparation method according to claim 6, characterized in that: The mass ratio of the starch nanoparticles to the polyphenols is 10:1 to 1:2; The emulsification method includes one or more of vortexing, homogenization, and ultrasound, and the emulsification time is 0.5 to 10 minutes; The volume fraction of the oil phase is 5 to 80 v / v%.

8. The preparation method according to claim 7, characterized in that: The metal ion is one or more of divalent copper ion, divalent zinc ion, trivalent iron ion, trivalent aluminum ion and tetravalent zirconium ion; the molar ratio of the metal ion to the polyphenol is 1:4 to 4:1, and the pH of the system is 3 to 9; The centrifugal speed is 3000-15000 rpm, the centrifugal time is 1-10 minutes, and the number of centrifugal times is 2-8 times.

9. Use of the sunscreen microcapsules with starch-based wall materials prepared by the preparation method according to any one of claims 1 to 8 in the preparation of cosmetics.

10. Use of a microcapsule with a starch-based wall material in the preparation of a biocompatible sunscreen, characterized in that: include, The starch nanoparticle dispersion, the polyphenol solution and the oil-soluble chemical sunscreen component are mixed and emulsified to obtain a water-in-oil-soluble chemical sunscreen Pickering emulsion; Metal ions are introduced into the obtained emulsion, and the pH value of the system is adjusted to promote the metal ions and polyphenols to form a network structure, and a biocompatible sunscreen is obtained through centrifugal washing.

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