CN113143785A

CN113143785A - Natural polyphenol functionalized antioxidant compound sunscreen agent and preparation method thereof

Info

Publication number: CN113143785A
Application number: CN202110362354.0A
Authority: CN
Inventors: 孟令杰; 杨婷婷; 王大权
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2021-04-02
Filing date: 2021-04-02
Publication date: 2021-07-23

Abstract

A natural polyphenol functionalized antioxidant composite sunscreen agent and a preparation method thereof, wherein a commercial physical sunscreen agent zinc oxide and titanium dioxide nano particles are used as a core, and natural polyphenol resveratrol functionalized polyphosphazene is used as a core-shell structure of a coating layer; during preparation, resveratrol which is a natural polyphenol with excellent ultraviolet absorption capacity and antioxidant effect is easily copolymerized with hexachlorocyclotriphosphazene and is easily deposited on the surfaces of zinc oxide and titanium dioxide nanoparticles, so that the risks of skin aging and in-vivo accumulation caused by the fact that the zinc oxide and titanium dioxide nanoparticles generate active oxygen species under ultraviolet illumination can be eliminated; meanwhile, the resveratrol serving as a natural sun-screening agent provides enhanced sun-screening effect and antioxidant effect; the composite sun-screening agent has extremely low transdermal risk due to the larger particle size, and the polyphosphazene structure endows the composite sun-screening agent with excellent stability; the preparation method is simple and easy to operate, and the commercialized easily-obtained raw materials are used, so that the cost is low.

Description

Natural polyphenol functionalized antioxidant compound sunscreen agent and preparation method thereof

Technical Field

The invention relates to the field of skin protection products, in particular to a natural polyphenol functionalized antioxidant compound sunscreen agent and a preparation method thereof.

Background

Solar ultraviolet radiation is classified into three categories according to wavelength, including UVA (400-315nm), UVB (315-280nm) and UVC (280-100 nm). UVC is completely reduced and dispersed by ozone-oxygen cycling, with the remaining UVA and part of UVB reaching the surface. Short-term UVB radiation has positive factors for the skin, such as cholecalciferol (vitamin D) synthesis, but high doses of solar Ultraviolet (UV) rays are harmful, and can cause erythema (sunburn), premature skin aging and skin cancer. To counteract these adverse effects, the use of sunscreen products containing active uv-filtering ingredients is a common measure of protection. These products may contain a combination of inorganic and organic compounds that provide protection through the process of absorbing, scattering and reflecting incident ultraviolet radiation.

In the sunscreen skin care product, the main effective components are chemical sunscreen agents, physical sunscreen agents and natural sunscreen agents. Most chemical sunscreen agents are aromatic compounds, such as Homosalate (HMS), Avobenzone (AVB), Orlistat (OCT), which have good uv absorption but can decompose to produce free radicals under light, and can produce side effects such as skin irritation and in vivo enrichment, reduce thyroxine levels, even cause cancer, and present a great potential risk. Heiden et al found that in humans, 2% of benzophenone-3 and its metabolites are excreted through the urine after topical application, indicating that small organic molecules can penetrate the skin into the circulatory system.

It is therefore essential to avoid direct contact with these small molecule chemical sunscreens. The physical sunscreens titanium dioxide nanoparticles and zinc oxide nanoparticles have been proven to be excellent in protecting skin from ultraviolet radiation, and are widely used in sunscreen creams. But it causes skin aging due to strong oxidative free radicals generated under uv irradiation and may penetrate damaged skin to be concentrated in liver and kidney. In recent years, sunscreen products based on natural antioxidants have attracted considerable attention. The natural sunscreen agent is natural extract active ingredients with sunscreen effect, such as carotene, flavone compounds and the like, mostly has a polyphenol structure and has strong antioxidant activity, and simultaneously has strong absorption on ultraviolet rays, thereby achieving the effects of resisting aging and repairing skin. However, the development of high-end products to which active ingredients of natural extracts are added is limited due to their susceptibility to oxidation during storage. At present, the technology commonly used by high-end sunscreen brands abroad for keeping the stability and the sustained release performance of active ingredients is mainly carried out by utilizing microcapsules, porous polymers and the like. In China, related research is still in the initial stage, and the high-end product field is almost completely occupied by foreign brands.

Disclosure of Invention

Aiming at the problems in the existing sunscreen products, the invention aims to provide a natural polyphenol functionalized antioxidant compound sunscreen agent and a preparation method thereof, the prepared antioxidant compound sunscreen agent can eliminate the risks of skin aging caused by ROS generation of a physical sunscreen agent and in-vivo enrichment of a chemical sunscreen agent, has antioxidant and enhanced sunscreen effects, and is beneficial to activity maintenance and slow release of active ingredients of a natural extract.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a kind of natural polyphenol functionalized anti-oxidation compound sunscreen agent comprises a natural polyphenol functionalized polyphosphazene shell layer; the natural polyphenol in the natural polyphenol functionalized polyphosphazene shell layer comprises one of resveratrol, naringenin and curcumin EGCG and contains at least two phenolic hydroxyl groups; the polyphosphazene is a cross-linked polyphosphazene prepared by copolymerization of hexachlorocyclotriphosphazene and a natural polyphenol compound;

the natural polyphenol functionalized polyphosphazene shell is a shell with controllable thickness in the sun-screening agent or is an independent nano particle.

The natural polyphenol functionalized antioxidant composite sunscreen agent further comprises an inner core, wherein the inner core is zinc oxide or titanium dioxide nanoparticles, and the zinc oxide or titanium dioxide nanoparticles are zinc oxide or titanium dioxide nanoparticles for commercial sunscreen agents.

The preparation method of the antioxidant compound sunscreen agent based on the natural polyphenol functionalization comprises the following steps:

putting hexachlorocyclotriphosphazene HCCP and a natural polyphenol compound into a round-bottom flask, and dispersing the hexachlorocyclotriphosphazene HCCP and the natural polyphenol compound into an organic solvent under ultrasonic to obtain a dispersion liquid;

adding organic base into the dispersion liquid under ultrasound;

step (3), carrying out ultrasonic reaction for a certain time under the condition of proper temperature;

and (4) centrifugally separating a solid product from the reacted mixed solution, washing the solid product by using absolute ethyl alcohol and deionized water respectively, and drying the solid product in vacuum at a certain temperature to obtain a white powder product.

The natural polyphenol compound in the step (1) is one of resveratrol, naringenin, curcumin and EGCG.

In the step (1), hexachlorocyclotriphosphazene HCCP and natural polyphenol compounds form a shell material, and the feeding molar ratio is 1: 5-5: 1.

In the step (1), the organic solvent is one of acetonitrile, tetrahydrofuran and acetone, and 50-200mL of the organic solvent is added into every 100mg of hexachlorocyclotriphosphazene HCCP.

Titanium dioxide or zinc oxide nanoparticles are further added in the step (1), titanium dioxide TiO2 or zinc oxide ZnO is used as a core material, and the mass ratio of the core material to a shell material is 1: 4-4: 1;

the organic base in the step (2) is triethylamine, and the dosage of the organic base is 1:200-1:20 of the volume dosage of the organic solvent in the step (1)

The ultrasonic power in the step (1), the step (2) and the step (3) is 50-800W.

The reaction temperature of the step (3) is 20-80 ℃, and the reaction time is 0.1-6 h.

The centrifugal speed in the step (4) is 10000rpm, and the vacuum drying temperature is 40-60 ℃.

The invention has the advantages and effects that:

the invention prepares the natural polyphenol functionalized antioxidant compound sun-screening agent with oxidation resistance and sun-screening performance by a one-pot method. By selecting different phenolic compounds, a functionalized composite sun-screening agent can be obtained, and verified that the compound sun-screening agent has two types of resveratrol and naringenin, and has strong sun-screening performance because the ring structures of the compound sun-screening agent can have certain chemical absorption in a UVB region and can play a good reflection role on a UVA region from a frame structure; meanwhile, the antioxidant property is excellent, after titanium dioxide or zinc oxide is coated, on the basis of the excellent sun-screening property of the original physical sun-screening agent, different polyphenols are introduced to obtain antioxidant capacity with different strengths, the antioxidant capacity is in positive correlation with the concentration, the obtained nanoparticles have long-acting slow-release free radical scavenging capacity different from that of a small molecular antioxidant, high free radical scavenging activity can be still maintained within eight hours, and the effect on skin is more gradual and longer-acting; in addition, the polyphenol type polyphosphazene microspheres as a sun-screening agent have higher safety, have higher biocompatibility, are made of nontoxic raw materials (HCCP) or are produced from pure natural ingredients (RES), are separated from the surface layer of the skin by a framework structure and cannot permeate through the skin compared with the traditional organic sun-screening agent, and meanwhile, the shell mechanism of the polyphosphazene also separates the skin from photocatalyst titanium dioxide and zinc oxide, so that the potential harm to a human body caused by ROS generated by photocatalysis is avoided, and the polyphenol type polyphosphazene microspheres are a safe and efficient antioxidant sun-screening agent.

Drawings

FIG. 1 (a-c) is a scanning electron micrograph of the products PPZ-TiO2, PPZ-ZnO, PPZ-RES obtained in examples 1 and 2, (d-f) is a transmission electron micrograph, and (g-i) is a dynamic light scattering hydration radius distribution diagram;

in FIG. 2, (a) is the IR pattern of the monomer and polymer nanoparticles synthesized in example 1, (b) is the XRD pattern, and (c-d) is the UV absorption spectrum in ethanol solution.

FIG. 3 shows the results of cell viability assay of the synthesized material of example 1, wherein (a) in FIG. 3 is a comparison of the viability of L929 cells after incubation for 8h (20-80. mu.g. mL-1) with PPZ-TiO2, PPZ-RES, PPZ-ZnO, and (b) - (d) are the viability of cells after incubation for 1h,2h, 4h, 8h with PPZ-TiO2, PPZ-RES, PPZ-ZnO, respectively.

FIG. 4 is the results of evaluation of skin penetration of ultraviolet filters of nanoparticles obtained in example 1, wherein (a) to (c) in FIG. 4 are skin tissue sections after incubation for 6h with fluorescein FL, FL-PPZ-TiO2, FL-PPZ-ZnO, respectively; (d) boxplots of fluorescence intensities for (a), (b), and (c); (e) the fluorescence spectra of three solutions of fluorescein FL, FL-PPZ-TiO2 and FL-PPZ-ZnO are corresponding to the fluorescence intensity.

FIG. 5 is a representation of the ultraviolet region performance of the PPZ-RES particles obtained in example 1 and the PPZ-TiO2 particles and PPZ-ZnO particles obtained in example 2, wherein (a) in FIG. 5 is a partial characterization of the chemical absorption in the ultraviolet region of the three nanoparticles; (b) the total reflection part of the ultraviolet region of three nano particles is characterized; (c) the stability of three nanoparticles and a certain commercial sunscreen cream BR is characterized when the three nanoparticles are continuously irradiated for 8 hours.

FIG. 6 is the evaluation of the in vitro UV resistance of the nanoparticles obtained in example 1, wherein (a) in FIG. 6 is a schematic diagram of the in vitro UV resistance test; (b) the cell survival rate is characterized in an unprotected state and under different protection conditions; (c) - (i) are pictures of live and dead cells under different protection conditions taken by an inverted fluorescence microscope (red cells, i.e. dead cells, within the white circle).

FIG. 7 is a histological picture of dorsal skin sections of mice subjected to different topical interventions before and after exposure to a large dose of UV light with nanoparticles obtained in example 1, wherein (a) in FIG. 7 is a schematic diagram of a body surface UV-resistant experiment; (b) - (l) is a histological picture prepared after the coating of different nanoparticles and the irradiation of sunlight; (m) (n) is the statistics of epidermal thickening corresponding to (b) - (l).

FIG. 8 shows the results of activity tests for removing 1, 1-diphenyl-2-picrylhydrazino DPPH radical by the synthesized products PPZ-RES, PPZ-TiO2 and PPZ-ZnO particles of examples 1 and 2, wherein (a) in FIG. 8 is a picture of 1, 1-diphenyl-2-picrylhydrazino DPPH ethanol solution at 0h after addition of RES, PPZ-TiO2 and PPZ-ZnO (both at a concentration of 2 mg. multidot.mL-1); (b) storing the solution in the step (a) for 8 hours at room temperature in a dark place; (c) the method is characterized by DPPH free radical scavenging experiment of PPZ-RES with different concentrations; (d) is characterized by DPPH free radical scavenging experiments of PPZ-TiO2 and PPZ-ZnO.

In FIG. 9, (a) is a transmission electron microscope, (b) is a scanning electron microscope, and (c) is an infrared spectrum test of the synthesized PPZ-NAR nanoparticles of example 3.

In FIG. 10, (a) is the ultraviolet absorption spectrum of the synthesized PPZ-NAR nanoparticles of example 3 in diluted ethanol solution, (b) is the chemical absorption curve of solid ultraviolet, and (c) is the total reflection curve.

Fig. 11 is a schematic view of the core-shell structure of the antioxidant composite sunscreen agent of the present invention.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure. The principles of operation not described in detail in the present invention are well known in the art and the common general knowledge in the field, and should be known to those skilled in the art.

A natural polyphenol functionalized antioxidant composite sunscreen agent has a core-shell structure shown in figure 11, and is characterized by comprising a natural polyphenol functionalized polyphosphazene shell and a zinc oxide or titanium dioxide nanoparticle inner core; as shown in fig. 11, in the formula i, R is one of resveratrol, naringenin and curcumin EGCG, and contains at least two phenolic hydroxyl groups; II, the zinc oxide or titanium dioxide nano particles are commercial zinc oxide or titanium dioxide nano particles for the sun-screening agent.

The polyphosphazene is a cross-linked polyphosphazene prepared by copolymerizing hexachlorocyclotriphosphazene and a natural polyphenol compound.

The thickness of the natural polyphenol functionalized polyphosphazene shell layer in the antioxidant composite sunscreen agent is controllable, and the natural polyphenol functionalized polyphosphazene shell layer can also be independently formed into nano particles.

The particle size of the natural polyphenol functionalized antioxidant composite sunscreen agent is 100-1200 nm.

The antioxidant compound sunscreen agent with the natural polyphenol functionalization can be added with titanium dioxide or zinc oxide as an inner core, and can also be polymerized into nano particles without the inner core.

The preparation method of the antioxidant composite sunscreen agent based on the above refers to the following examples.

Example one

The preparation method adopts a one-pot precipitation polymerization method to prepare a hexachlorocyclotriphosphazene and resveratrol crosslinked product (PPZ-RES) without an inner core, and comprises the following steps:

(1) putting 90.0mg of hexachlorocyclotriphosphazene HCCP and 118.2mg of resveratrol RES into a 250ml round-bottom flask, and dispersing 100W of the mixture in 100ml of acetonitrile under ultrasonic waves to obtain a dispersion liquid;

(2) 2mL Triethylamine (TEA) was added to the dispersion under 100W ultrasound;

(3) placing the flask in a 100W ultrasonic reaction chamber for 30min, wherein the reaction temperature is 20 ℃;

(4) after the reaction was completed, the solid product was separated by centrifugation and then washed 3 times with anhydrous ethanol and deionized water, respectively. Finally, the suspension was freeze-dried for 48 hours to obtain PPZ-RES as a white powder.

Example two

The preparation method of the cross-linking product PPZ-TiO2 and PPZ-ZnO of hexachlorocyclotriphosphazene and resveratrol added with TiO2 and provided with an inner core is similar to that of the cross-linking product PPZ-TiO2, and comprises the following steps:

(1) 129.6mg of hexachlorocyclotriphosphazene HCCP, 170.4mg of resveratrol RES and TiO₂200mg of the mixture is placed in a 250ml round-bottom flask and is dispersed in 100ml of acetonitrile under 400W of ultrasound to obtain a dispersion liquid;

(2) 5mL of Triethylamine (TEA) was added to the dispersion under 400W ultrasound;

(3) placing the flask in 400W ultrasonic reaction for 6h, wherein the reaction temperature is 80 ℃;

(4) after the reaction was completed, the solid product was separated by centrifugation and then washed 3 times with anhydrous ethanol and deionized water, respectively. Finally, freeze-drying for 48h to obtain PPZ-TiO₂As a white powder.

Shown as figure 1 are respectively (a) PPZ-RES and (b) PPZ-TiO₂(c) scanning electron microscope picture of PPZ-ZnO, transmission electron microscope and corresponding element distribution as (d) PPZ-RES, (e) PPZ-TiO₂And (f) PPZ-ZnO. Measuring the spectrum by dynamic light scattering spectrometry, (g) the hydration diameter of PPZ-RES is about 613nm, and the PDI is about0.038, Zeta potential value of-23.5 mV, (h) PPZ-TiO₂The hydrated diameter is about 479.4nm, the PDI is about 0.375, the Zeta potential value is-27.4 mV, (i) the hydrated diameter of PPZ-ZnO is about 258.2nm, the PDI is about 0.053, and the Zeta potential value is-27 mV, which shows that the prepared nano-particles have better dispersion stability.

FIG. 2 (a) demonstrates the binding of P-Cl to the covalent bond of O-H by Fourier transform Infrared Spectroscopy (FTIR), demonstrating PPZ-RES, PPZ-TiO₂And formation of PPZ-ZnO. It is shown that RES is 3300cm after the reaction^-1The characteristic peak of (A) disappears, and 1160cm^-1The P ═ N characteristic peak at the phosphazene ring also demonstrates polymerization of HCCP with RES. As can be seen from the XRD spectrum of fig. 2 (b), each peak pattern remains excellent. And the PPZ-RES is proved to be in TiO by the characteristic peak around 25₂And the surface of ZnO is successfully coated. As shown in FIGS. 3(c) and (d), when the monomers and the crosslinked product after polycondensation are respectively tested by an ultraviolet spectrophotometer, RES has a strong absorption peak at about 320nm, the absorption peak is red-shifted after the reaction, and the product has an absorption peak at about 350nm, which indicates the successful progress of the reaction.

Cytotoxicity is measured by using Cell Counting Kit-8 (CCK-8) for PPZ-RES and PPZ-TiO₂And PPZ-ZnO were quantitatively evaluated for biocompatibility. L929 cells were seeded into 96-well plate culture plates. Incubated overnight with 100. mu.L of PPZ-RES, PPZ-TiO₂And PPZ-ZnO (20. mu.g. mL)^-1，40μg·mL^-1，60μg·mL^-1And 80. mu. mL^-1) The medium was maintained at 37 ℃ for 1h,2h, 4h and 8h, respectively. 100mL of CCK-8 solution was used in place of the original medium. After 4 hours of incubation, the absorbance was measured at 450 nm. Normal L929 cells cultured at the same time interval served as a control. As shown in FIG. 3, (a) shows that the concentration of L929 cells is 20-80. mu.g.mL^-1PPZ-TiO of₂And the result of incubation in the culture solution of three polyphosphazene sun-protection nanoparticles PPZ-ZnO and PPZ-RES for 8 hours shows that the cytotoxicity of each nanoparticle is slightly increased along with the increase of the concentration, but the overall survival rate is kept higher and reaches more than 80%, and the toxicity is derived from the toxicity of RES molecules and ZnO nanoparticles. (b) (c) (d) PPZ-TiO, respectively₂PPZ-ZnO, PPZ-RES and L929 cells at a concentration of 20-80. mu.g/mL^-1The results obtained by incubating the culture solution for 1h,2h, 4h and 8h further show that the weak toxicity of the culture solution is slightly increased along with the increase of time, but the whole toxicity is not strong and the safety is high.

Dispersed in ethanol at a weight concentration of 10%, fluorescein FL was also dissolved in ethanol and its fluorescence intensity was adjusted to match the fluorescein-crosslinked polyphosphazene polyphenol sunscreen nanoparticle (FL-PPZ-RES, FL-PPZ-ZnO) solution. The 3 solutions were topically applied to the dorsal skin of nude mice. After 6 hours of incubation, each skin sample was topically washed 3 times with ethanol and water, 5 minutes each time and dried. The dorsal skin was excised and prepared for histological examination. After the samples were fixed in 4% paraformaldehyde for 24h, embedded in paraffin and cut into 4 μm sections. The tissue section was photographed under an inverted fluorescence microscope as shown in FIG. 4. After six hours of incubation, (a) the FL small molecule solution coated skin produced strong fluorescence, indicating that FL penetrated into nude mouse skin tissue, while FL-PPZ-TiO was coated₂(the size is equivalent to that of PPZ-RES, the same fluorescent particle is selected for experiment) the outer surface of the skin of the nude mouse of the solution (b) and the FL-PPZ-ZnO solution (c) is slightly fluorescent, and no obvious fluorescence exists inside, which indicates that the skin blocks the two nano particles outside and does not enter the skin through epidermis, and the box plot diagram (d) also indicates that the fluorescent intensity of coating FL is more than 10 percent, and the fluorescent intensity of coating the dispersion liquid of the other two nano particles is not more than 2 percent; (e) the fluorescence spectra of the three solutions with equivalent fluorescence intensity. The skin permeability experiment proves that PPZ-RES and PPZ-TiO₂The three nano particles and PPZ-ZnO nano particles can not permeate into skin through epidermis, which proves that the polyphosphazene nano sunscreen particles have high safety.

The PPZ-RES was dispersed in ethanol (10% wt%) as measured and analyzed by a UV integrating sphere. The suspension was dropped onto a clean quartz slide (r 1cm) to ensure 2.0mg cm^-2Is used for covering. After drying, a second quartz slide of the same size was placed on top of the sample to protect it. The PPZ-TiO was prepared in the same manner as the above-described PPZ-TiO by obtaining the UV-visible absorption spectrum of the tablet on a Perkin-Elmer Lambda 750 UV/visible spectrophotometer equipped with an integrating sphere (FIGS. 5(a) (b))₂And PPZ-ZnO tablets.

As shown in FIG. 5Wherein (a) is PPZ-TiO₂The chemical absorption parts of the PPZ-ZnO and PPZ-RES nano particles in the ultraviolet region, and (b) reflects the reflection efficiency of the three polyphosphazene sun-protection nano particles. (c) To mix PPZ-TiO₂PPZ-ZnO and PPZ-RES nanoparticles and some commercial sunscreen cream were coated on a quartz plate (both 1 mg. cm)^-2) Fluorescent lamp 3mw cm^-2The stability line graph measured by continuous irradiation for 8h shows that under the continuous long-time high-intensity sunshine condition, the prepared polyphosphazene sunscreen nano particles have high sunscreen activity which is not output to commercial sunscreen cream, and can provide long-acting ultraviolet protection for skin.

The polyphosphazene sunscreen nanoparticles were tested for in vitro UV resistance, as shown in the schematic diagram of FIG. 6(a), normal cells were covered with tinfoil for protection against light, control groups were covered with only clean quartz plates, and a certain amount of ethanol dispersion of nanoparticles was coated on 2cm by 2cm quartz plates to ensure coverage of 0.5mg cm^-2The cells were overlaid on a 96-well plate for culturing L929 cells, and the plate was irradiated with UVB light at 400. mu.W.cm^-2After 30min of irradiation, the cells are incubated in a constant temperature incubator for 24h, and the survival rate of the cells is shown in fig. 6(b), compared with the cells which are not protected and irradiated by ultraviolet rays, the survival rate of the cells protected by the polyphosphazene sun-screening nanoparticles is equivalent to the survival rate of the cells which are not normally irradiated by ultraviolet rays. Meanwhile, AM/PI staining is carried out on the cells after the operations are repeated, live and dead cell pictures such as (c) - (i) are obtained through an inverted fluorescence microscope, red cells are dead cells (white circles are circled), green cells are live cells (other cells except the white circles), and the protection effect of the polyphosphazene sunscreen nanoparticles on the cells can be visually seen.

To further verify the sunscreen effect of polyphosphazene sunscreen nanoparticles, animal experiments were performed, in which the skin on the back of nude mice was divided into 6 quadrants as shown in fig. 7(a), normal skin was masked, the other quadrants were uniformly coated with (10% wt) dispersion containing different polyphosphazene sunscreen nanoparticles, and hematoxylin eosin (H) was performed on the skin on the back of normal mice after uv irradiation&E) Dyeing with total ultraviolet dose of 4320J · m^-2. The images of the nude mouse epidermal tissue section are shown in FIGS. 7(b) - (i), where (m) and (n) are PPZ-TiO, respectively₂And relative thickening of nude mouse epidermis under protection of PPZ-ZnO system, PPZ-TiO₂And the PPZ-ZnO provides long-acting protection for the skin under long-term ultraviolet irradiation, the thickness of the epidermis is slightly thicker than that of the normal skin without ultraviolet irradiation, the protection effect is provided to a great extent, and the excellent sun-screening performance of the polyphosphazene sun-screening nano particles is demonstrated.

To verify the antioxidant properties of the prepared polyphosphazene sunscreen nanoparticles, a pure 1, 1-diphenyl-2-picrylhydrazino (DPPH) solution was prepared as a control as shown in FIG. 8(a), and RES, PPZ-RES, PPZ-TiO were added to the other components₂And PPZ-ZnO nanoparticles (2 mg. mL) in mass concentration^-1) After RES micromolecules are added, the DPPH solution rapidly fades, which shows that RES has very strong free radical scavenging capacity, and other RES can be used as TiO in test tubes instantly₂The use is not obvious; after 8h of storage at room temperature in the dark, the effect of PPZ-RES and PPZ-TiO can be seen after 8h as shown in (b)₂And the color of the test tube of the PPZ-ZnO nano particles also becomes light to fade, while the test tube of a single DPPH free radical still presents purple, which preliminarily verifies that the synthesized polyphosphazene sun-screening nano particles have oxidation resistance and can play a long-acting mild anti-oxidation role. In order to further verify the antioxidant effect, 0.2-2 mg/mL is adopted^-1The PPZ-RES of (a) is verified, and as shown in (c), the antioxidant performance of the PPZ-RES shows obvious concentration dependence, and the antioxidant performance is gradually enhanced along with the increase of the concentration. The concentration is 2 mg/mL^-1The good free radical scavenging effect can be achieved within 8 hours, and (d) is selected from 2 mg/mL^-1PPZ-TiO with equivalent PPZ-RES content₂And PPZ-ZnO is subjected to DPPH free radical scavenging test, and the antioxidant effect of the two nanoparticles is well maintained.

EXAMPLE III

This example synthesizes hexachlorocyclotriphosphazene and naringenin to prepare polyphosphazene sunscreen agents. The method for preparing the cross-linked product PPZ-NAR of hexachlorocyclotriphosphazene and naringenin is similar to the PPZ-RES, and comprises the following steps:

(1) putting 90.0mg of hexachlorocyclotriphosphazene HCCP and 140.96mg of naringenin NAR in a 250ml round-bottom flask, and dispersing in 50ml of acetonitrile under ultrasonic to obtain a dispersion liquid;

(2) add 0.5mL Triethylamine (TEA) to the dispersion under ultrasound;

(3) placing the flask in a 100W ultrasonic reaction chamber for 0.1h, wherein the reaction temperature is 25 ℃;

(4) after the reaction was completed, the solid product was separated by centrifugation and then washed 3 times with anhydrous ethanol and deionized water, respectively. Finally, the suspension was freeze-dried for 48 hours to obtain PPZ-NAR as a yellow powder.

As can be seen by transmission electron microscope and scanning electron microscope, the particle diameter of PPZ-NAR can reach 800nm, as shown in FIGS. 9(a), (b) and (c), FIIR spectrogram 1160cm^-1The P ═ N characteristic peak at the phosphazene ring also demonstrates the polymerization of HCCP with NAR. Ultraviolet absorption of NAR small molecules and PPZ-NAR nano particles in an ethanol dilute solution is measured as shown in figure 10(a), and it can be seen that the absorption peak of the product is red-shifted after cross-linking. The PPZ-NAR was dispersed in ethanol (10% by weight) as measured and analyzed by a UV integrating sphere. The suspension was dropped onto a clean quartz slide (r 1cm) to ensure 2.0mg cm^-2Is used for covering. After drying, a second quartz slide of the same size was placed on top of the sample to protect it. The uv-vis absorption spectra of the tablets were obtained on a Perkin-Elmer Lambda 750 uv/vis spectrophotometer equipped with integrating spheres (fig. 10(b) (c)), (b) is the chemical absorption portion of PPZ-BAR nanoparticles in the uv region with strong chemical absorption before 350nm, and (c) shows the reflection efficiency of the above polyphosphazene sunscreen nanoparticles.

Claims

1. A natural polyphenol functionalized antioxidant composite sunscreen agent is characterized by comprising a natural polyphenol functionalized polyphosphazene shell layer; the natural polyphenol in the natural polyphenol functionalized polyphosphazene shell layer comprises one of resveratrol, naringenin and curcumin EGCG and contains at least two phenolic hydroxyl groups; the polyphosphazene is a cross-linked polyphosphazene prepared by copolymerization of hexachlorocyclotriphosphazene and a natural polyphenol compound;

2. A natural polyphenol functionalized antioxidant composite sunscreen agent is characterized by also comprising an inner core, wherein the inner core is zinc oxide or titanium dioxide nanoparticles, and the zinc oxide or titanium dioxide nanoparticles are zinc oxide or titanium dioxide nanoparticles for a commercial sunscreen agent.

3. The preparation method of the antioxidant compound sunscreen agent based on the natural polyphenol functionalization is characterized by comprising the following steps:

adding organic base into the dispersion liquid under ultrasound;

4. The method for preparing the antioxidant compound sunscreen agent functionalized by natural polyphenols according to claim 3, characterized in that,

5. The method for preparing the antioxidant compound sunscreen agent functionalized by natural polyphenols according to claim 3, characterized in that,

in the step (1), hexachlorocyclotriphosphazene HCCP and natural polyphenol compounds form a shell material, and the feeding molar ratio is 1: 5-5: 1; the organic solvent is one of acetonitrile, tetrahydrofuran and acetone, and 50-200mL of the organic solvent is added into every 100mg of hexachlorocyclotriphosphazene HCCP.

6. The method for preparing the antioxidant compound sunscreen agent functionalized by natural polyphenols according to claim 5, wherein the sunscreen agent is a natural polyphenol compound sunscreen agent,

titanium dioxide or zinc oxide nanoparticles are further added in the step (1), titanium dioxide TiO2 or zinc oxide ZnO is used as a core material, and the mass ratio of the core material to a shell material is 1: 4-4: 1.

7. The method for preparing the antioxidant compound sunscreen agent functionalized by natural polyphenols according to claim 3, characterized in that,

the organic base in the step (2) is triethylamine, and the dosage of the organic base is 1:200-1:20 of the volume dosage of the organic solvent in the step (1).

8. The method for preparing the antioxidant compound sunscreen agent functionalized by natural polyphenols according to claim 3, characterized in that,

the ultrasonic power in the steps (1), (2) and (3) is 50-800W.

9. The method for preparing the antioxidant compound sunscreen agent functionalized by natural polyphenols according to claim 3, characterized in that,

10. The method for preparing the antioxidant compound sunscreen agent functionalized by natural polyphenols according to claim 3, characterized in that,

the centrifugal rotation speed of the step (4) is 10000rpm, the washing solvent is absolute ethyl alcohol and deionized water, and the vacuum drying temperature is 40-60 ℃.