Supramolecular assembled tannic acid-zinc nanoparticle and application thereof in cosmetics

Abstract

The application discloses a supramolecular assembly tannic acid-zinc nanoparticle and application thereof in cosmetics. The supramolecular assembly tannic acid-zinc nanoparticle is an aggregate structure formed by tannic acid and zinc pyrrolidone carboxylate through non-covalent interaction. A preparation method of the supramolecular assembly tannic acid-zinc nanoparticle comprises the following steps: ultrasonic treatment is conducted on a mixed solution composed of tannic acid, zinc pyrrolidone carboxylate and a solvent. The supramolecular assembly tannic acid-zinc nanoparticle can effectively exert the synergistic effect of tannic acid and zinc elements, and can guarantee excellent effects such as high stability and high transdermal absorption. The supramolecular assembly tannic acid-zinc nanoparticle itself and further application thereof in cosmetics can simultaneously consider excellent anti-photoaging and oil control effects.

Description

Technical Field

[0001] This invention relates to supramolecularly assembled tannic acid-zinc nanoparticles and their application in cosmetics, specifically to supramolecularly assembled tannic acid-zinc nanoparticles and their application in the preparation of cosmetics and their preparation method. Background Technology

[0002] Photoaging and excessive sebum secretion are major skin problems faced by contemporary populations, often working synergistically to exacerbate skin damage and imperfections. Photoaging is an exogenous aging process caused by prolonged exposure to ultraviolet radiation, coupled with environmental pollutants and free radical damage. Its core mechanism involves increased oxidative stress and activation of inflammatory pathways, leading to the degradation of collagen fibers in the dermis and decreased elasticity, manifesting as fine lines, wrinkles, pigmentation, and a damaged skin barrier. Excessive sebum secretion, on the other hand, easily leads to enlarged pores, acne, and dull skin tone. Furthermore, excess sebum accelerates the generation of UV-induced free radicals, further aggravating photoaging damage. Therefore, cosmetics that combine anti-photoaging and oil-controlling effects have become a hot research topic in the industry.

[0003] Tannic acid (TA), a natural polyphenol compound, is widely found in plants and possesses excellent antioxidant, anti-inflammatory, and anti-photoaging activities. Its molecular structure contains numerous phenolic hydroxyl groups that can effectively scavenge reactive oxygen species (ROS) in the skin, inhibit matrix metalloproteinases (MMPs) activity, reduce collagen degradation, and regulate skin keratin metabolism, thus helping to improve sebum secretion. Zinc, an essential trace element for the human body, is often used in cosmetics in the form of zinc pyrrolidone carboxylate, zinc oxide, and zinc sulfate. In particular, zinc pyrrolidone carboxylate (PCA-Zn) can inhibit UV-induced activation of transcription activator AP-1, reduce MMP production, promote type I collagen synthesis, and has significant oil-controlling, anti-inflammatory, and astringent effects. It can inhibit excessive sebum secretion, reduce skin inflammation, and enhance skin barrier function. The applications of tannic acid and PCA-Zn in skincare have been widely validated. However, the application of tannic acid and zinc in cosmetics faces many technical limitations, and existing skincare products and preparation technologies struggle to overcome these bottlenecks, failing to fully leverage their synergistic effects. Meanwhile, as consumers increasingly demand "highly effective, gentle, green, and safe" cosmetics, the shortcomings of existing technologies are becoming more and more apparent, as follows: 1. Poor stability of active ingredients and severe efficacy degradation: The special molecular structure of TA results in poor chemical stability, making it highly sensitive to changes in factors such as light, pH, and temperature, leading to a significant loss of its antioxidant and anti-photoaging activities. PCA-Zn also has limitations when used in cosmetic formulations, as it is highly susceptible to compatibility issues with certain thickeners or anionic surfactants, affecting system stability.

[0004] 2. Low transdermal absorption efficiency and limited efficacy: The barrier function of the stratum corneum makes it difficult for TA and zinc ions to penetrate effectively. Most active ingredients can only remain on the skin surface, resulting in a significant reduction in their anti-photoaging and oil-controlling effects. Even increasing the concentration of these two ingredients is unlikely to achieve the desired skincare results and may even increase the risk of skin irritation.

[0005] 3. The synergistic effect of TA and zinc has not been fully explored and is prone to antagonistic effects: In existing products, TA and PCA-Zn are mostly added alone or simply combined. When the two are combined, they are very likely to have antagonistic effects during the process, and the effects are relatively simple, making it difficult to achieve multi-target synergistic skin care.

[0006] 4. The preparation process is not gentle enough and does not conform to the concept of green chemistry: The current preparation process of cosmetics containing TA or zinc often requires the use of a large amount of organic solvents, high-temperature emulsification or high-pressure dispersion. On the one hand, it will destroy the polyphenol structure of TA and aggravate its oxidative degradation, and may also affect the activity of zinc ions. On the other hand, the residual organic solvent will increase the risk of skin irritation, which is not in line with the current trend of green manufacturing and environmental protection and low carbon in the cosmetics industry.

[0007] Therefore, there is an urgent need for a product that can effectively leverage the synergistic effects of TA and zinc, while ensuring high stability, high transdermal absorption, and a gentle manufacturing process. Summary of the Invention

[0008] To address the shortcomings of existing cosmetics containing tannic acid or zinc, such as poor stability, low transdermal absorption efficiency, and low efficacy, this invention provides supramolecularly assembled tannic acid-zinc nanoparticles, their application in cosmetic preparation, and their preparation method. These supramolecularly assembled tannic acid-zinc nanoparticles effectively leverage the synergistic effects of tannic acid and zinc, ensuring high stability and high transdermal absorption. Furthermore, both the nanoparticles themselves and their application in cosmetics simultaneously provide excellent anti-photoaging and oil-controlling effects, and can be prepared without complex processes.

[0009] To achieve the above objectives, the present invention adopts the following technical solution.

[0010] This invention provides a supramolecularly assembled tannic acid-zinc nanoparticle, wherein the supramolecularly assembled tannic acid-zinc nanoparticle is an aggregate structure formed by non-covalent interaction between tannic acid and zinc pyrrolidone carboxylate.

[0011] In this invention, the term "supramolecular" refers to a molecular aggregate formed by two or more molecules through non-covalent intermolecular interactions. Specifically, in this invention, "supramolecularly assembled tannic acid-zinc nanoparticles" corresponds to a molecular aggregate formed by tannic acid and zinc pyrrolidone carboxylate through non-covalent interactions. Those skilled in the art will understand its specific meaning.

[0012] This invention has revealed that when tannic acid and zinc pyrrolidone carboxylate are combined, simply involving the physical mixing of the two cannot effectively promote penetration and still cannot solve the core problems of poor stability and insufficient transdermal absorption of the two. However, during the specific research and development process, this invention unexpectedly discovered that supramolecularly assembled tannic acid-zinc nanoparticles obtained through supramolecular assembly technology can effectively solve the technical pain points while significantly improving the effects of anti-photoaging, oil control, anti-oxidation, and anti-aging, giving full play to the synergistic effect of the two.

[0013] In this invention, the non-covalent interaction may include one or more of hydrogen bonds, π-π stacking, and van der Waals forces.

[0014] In some embodiments, the molar ratio of the tannic acid and zinc pyrrolidone carboxylate is 1:(5-8), preferably 1:(6-7).

[0015] In some preferred embodiments, the molar ratio of tannic acid and zinc pyrrolidone carboxylate is 1:6.

[0016] In some embodiments, the hydrated particle size of the supramolecularly assembled tannic acid-zinc nanoparticles is 110-150 nm, for example, 120-135 nm.

[0017] In some embodiments, the PDI of the supramolecularly assembled tannic acid-zinc nanoparticles is 0.05-0.20, for example, 0.08-0.15.

[0018] In some embodiments, the Zeta potential of the supramolecularly assembled tannic acid-zinc nanoparticles is -25 to -35 mV, for example -28 to -33 mV.

[0019] This invention also provides a method for preparing supramolecularly assembled tannic acid-zinc nanoparticles, the method comprising the following steps: A mixed solution consisting of tannic acid, a zinc-containing compound, and a solvent was subjected to ultrasonic treatment.

[0020] The present invention has shown that only an ultrasonic treatment step is needed to rapidly and uniformly drive molecules (tannic acid, zinc pyrrolidone carboxylate) to complete self-assembly through non-covalent interactions. In addition, the initial disordered aggregation state can be broken during the process, inducing directional alignment and promoting the effective formation of non-covalent interactions. Furthermore, this method can avoid random aggregation caused by excessively high local concentrations, achieve uniform nucleation and growth, and facilitate the formation of supramolecular structures with uniform size and morphology.

[0021] In some embodiments, the molar ratio of the tannic acid and zinc pyrrolidone carboxylate is 1:(5-8), preferably 1:(6-7).

[0022] In some implementations, the solvent is PBS buffer. Studies have shown that PBS buffer is significantly superior in overall performance (especially encapsulation efficiency) compared to common cosmetic solvents such as ethanol.

[0023] In some embodiments, the pH of the solvent is 6.5-8.0, preferably 7.0-7.5.

[0024] In some embodiments, the power of the ultrasonic treatment is 200-500W, preferably 300-400W.

[0025] The research conducted by this invention has revealed that, based on the aforementioned overall steps, further optimization of key parameters (such as the molar ratio of tannic acid and zinc pyrrolidone carboxylate, solvent type, solvent pH, ultrasonic power, etc.) can achieve a relatively optimal improvement in stability, transdermal absorption, and multiple efficacy aspects.

[0026] Accordingly, in some preferred embodiments, the molar ratio of tannic acid and zinc pyrrolidone carboxylate is 1:6; the pH of the PBS buffer is 7.5; and the power of the ultrasonic treatment is 300W.

[0027] In some implementations, the ultrasound treatment time is 5-20 minutes, for example, 10 minutes.

[0028] In some embodiments, the ultrasonic treatment is performed in an ice-water bath, the temperature of which may be 0°C as commonly understood in the art.

[0029] In some embodiments, the ultrasonic treatment is performed in an ultrasonic cell disruptor.

[0030] In some embodiments, the tannic acid and the zinc-containing compound are each added independently to the solvent in the form of aqueous solutions, and then mixed to obtain the mixed solution; specifically, they can be added to the solvent dropwise.

[0031] The dripping speed can be selected according to actual needs, for example, 20 drops / min.

[0032] In some embodiments, the ultrasonic treatment further includes centrifugation to collect the precipitate and washing. These centrifugation and washing steps effectively remove unreacted monomers, solvents, and small aggregates present in the reaction system.

[0033] The centrifugation speed is preferably 6000-10000 rpm, for example 8000 rpm.

[0034] The centrifugation time is preferably 5-20 min, for example 10 min.

[0035] The washing is preferably performed with deionized water, and the number of washing cycles is, for example, 3.

[0036] The present invention also provides supramolecularly assembled tannic acid-zinc nanoparticles, which are prepared by the preparation method of supramolecularly assembled tannic acid-zinc nanoparticles as described above.

[0037] In some embodiments, the supramolecularly assembled tannic acid-zinc nanoparticles are as defined above.

[0038] This invention also provides the application of supramolecularly assembled tannic acid-zinc nanoparticles as described above in the preparation of cosmetics.

[0039] In this invention, research has shown that the cosmetic product may possess one or more of the following effects: anti-photoaging, oil control, anti-oxidation, anti-inflammation, anti-aging, soothing, skin cell protection, skin cell repair, and moisturizing.

[0040] In this invention, the content of the supramolecular assembled tannic acid-zinc nanoparticles in the cosmetic product can be 0.2wt%-1.0wt%.

[0041] In this invention, the supramolecularly assembled tannic acid-zinc nanoparticles are applicable to the preparation of various cosmetics, such as one or more of face masks, gels, serums, essences, and creams.

[0042] In this invention, the cosmetic can be supplemented with conventional active ingredients or excipients (such as one or more of thickeners, moisturizers, antioxidants, solubilizers, preservatives, and fragrances) as needed, and each component can be added in accordance with conventional types and amounts in the art, and prepared in accordance with conventional preparation processes in the art.

[0043] In some specific embodiments, the cosmetic is a serum; the serum comprises the following components by weight percentage: 0.2wt%-1.0wt% of the supramolecularly assembled tannic acid-zinc nanoparticles; 0.1wt%-0.5wt% thickener, said thickener including xanthan gum and / or carbomer; 5wt%-15wt% humectant, wherein the thickener comprises one or more of glycerin, 1,3-dibutanol, sodium hyaluronate, glyceryl polyether-26, methyl glucetol polyether-20 and ceramide; 0.1wt%-0.5wt% antioxidant, said antioxidant including ascorbic acid and / or tocopheryl acetate; 0.4wt%-1wt% solubilizer, wherein the solubilizer comprises PEG-40 hydrogenated castor oil; 1wt%-3wt% of preservative, wherein the preservative comprises phenoxyethanol and / or 1,2-hexanediol; 0.2wt%-1wt% Fragrance.

[0044] In some specific embodiments, the cosmetic is a serum; the preparation method of the serum includes the following steps: S1. Mix the thickener, humectant, solubilizer and a portion of water to obtain mixture A; S2. Mix the tannic acid-zinc nanoparticles, antioxidant, preservative, fragrance and remaining water to obtain mixture B; S3. Add the mixture B to the mixture A, homogenize, and obtain the essence.

[0045] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0046] The reagents and raw materials used in this invention are all commercially available.

[0047] The positive and progressive effects of this invention are as follows: 1. The supramolecularly assembled tannic acid-zinc nanoparticles of the present invention utilize supramolecular technology to significantly improve the stability, transdermal performance and formulation compatibility of tannic acid and zinc pyrrolidone carboxylate, and can also give full play to the synergistic effect of the two, greatly expanding the application scope of TA and PCA-Zn in the cosmetic field.

[0048] 2. The supramolecularly assembled tannic acid-zinc nanoparticles of this invention exhibit excellent performance in anti-photoaging, oil control, anti-oxidation, anti-inflammation, anti-aging, soothing, skin cell protection, skin cell repair, and moisturizing effects. They combine the multiple benefits of tannic acid and zinc pyrrolidone carboxylate, forming a synergistic system of "antioxidant-anti-inflammatory-anti-photoaging-oil control." Furthermore, compared to the simple physical mixture system of tannic acid and zinc pyrrolidone carboxylate, they demonstrate significantly superior synergistic effects.

[0049] 3. The supramolecular assembly method for preparing tannic acid-zinc nanoparticles developed in this invention is characterized by mild conditions throughout the process, simple preparation, high reproducibility, no need for organic solvents, and conforms to the principles of green chemistry. Attached Figure Description

[0050] Figure 1 This illustrates the effect of different reaction solvents on the TA-Zn MPNs parameters in Example 2. P <0.05, P <0.01, P <0.001.

[0051] Figure 2 This illustrates the effect of different reaction solvent pH values ​​on the parameters of TA-Zn MPNs in Example 2. P <0.05, P <0.01, P <0.001.

[0052] Figure 3 The effect of different molar ratios of TA and PCA-Zn on the MPNs parameters of TA-Zn in Example 2. P <0.05, P <0.01, P <0.001.

[0053] Figure 4 This illustrates the effect of different ultrasonic powers on the parameters of TA-Zn MPNs in Example 2. P <0.05, P <0.01, P <0.001.

[0054] Figure 5 The image shows the particle size distribution and zeta potential of TA-Zn MPNs in Example 3. Figure 5 A represents the particle size distribution result; Figure 5 B is the potential diagram.

[0055] Figure 6 Electron microscope images of TA-Zn MPNs in Example 3. Figure 6 A is a TEM image of TA-Zn MPNs; Figure 6 B is the SEM image of TA-Zn MPNs.

[0056] Figure 7 The image shows the UV spectral scanning results of TA-Zn MPNs in Example 3.

[0057] Figure 8 The image shows the Fourier transform infrared spectral scanning results of TA-Zn MPNs in Example 3.

[0058] Figure 9 This is a graph showing the in vitro storage stability results of TA-Zn MPNs in Example 4. Figure 9 A is a graph showing the changes in particle size and PDI at 4 ℃; Figure 9 B represents the changes in particle size and PDI at 25 ℃; Figure 9 The graph shows the changes in particle size and PDI at 45 ℃. Figure 9 The graph shows the change in TA retention rate over 28 days (D). Figure 9 E represents the change in Zn retention rate over 28 days.

[0059] Figure 10 This is a graph showing the in vitro antioxidant performance results of TA-Zn MPNs in Example 5. Figure 10 A represents the DPPH free radical scavenging rate results; Figure 10 The graph with B representing the ABTS free radical scavenging rate is shown in Figure 1. Figure 10 The C value represents the hydroxyl radical scavenging rate. P <0.05, P <0.01, P <0.001.

[0060] Figure 11 This is a graph showing the in vitro transdermal performance results of TA-Zn MPNs in Example 6. Figure 11 A represents the cumulative skin penetration of TA; Figure 11 B represents the intradermal retention of TA; Figure 11 C represents the cumulative skin penetration of PCA-Zn; Figure 11 D represents the intradermal retention of PCA-Zn. P <0.05, P <0.01, P <0.001.

[0061] Figure 12 The figure shows the protective effect of TA-Zn MPNs against oxidative damage in HaCaT cells in Example 7. P <0.05, P <0.01, P <0.001.

[0062] Figure 13 This is a graph showing the effect of TA-Zn MPNs on the migration ability of HaCaT cells in Example 7. Figure 13 Image A is a representative image of HaCaT cell migration; Figure 13 Figure B shows the cell scratch healing rate. P <0.05, P <0.01, P <0.001.

[0063] Figure 14 The image shows the protective effect of TA-Zn MPNs against UVB damage in L929 cells in Example 7. P <0.05, P <0.01, P <0.001.

[0064] Figure 15 These are representative images from the mouse skin safety test in Example 10.

[0065] Figure 16 The image shows the results of the mouse skin moisture content test in Example 11. P <0.05, P <0.01, P <0.001.

[0066] Figure 17 This is a H&E staining image of mouse skin tissue pathology from Example 11.

[0067] Figure 18 This is a graph showing the levels of inflammatory factors in mouse skin tissue in Example 11. Figure 18 A represents the IL-1β content graph; Figure 18 B represents the IL-6 content graph; Figure 18 The C value represents the TNF-α content. P <0.05, P <0.01, P <0.001.

[0068] Figure 19 This is a diagram showing the results of extracellular matrix levels in mouse skin tissue in Example 11. Figure 19 A represents the content of Collagen I; Figure 19 B represents the MMP-1 content. P <0.05, P <0.01, P <0.001. Detailed Implementation

[0069] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0070] Example 1: Preparation of supramolecularly assembled tannic acid-zinc nanoparticles (TA-Zn MPNs)

[0071] The TA-Zn MPNs based on supramolecular technology of the present invention are specifically prepared by the following steps: (1) Accurately weigh a certain amount of tannic acid (TA) and zinc pyrrolidone carboxylate (PCA-Zn, also known as PCA-zinc), and prepare 6.8 mg / mL TA aqueous solution and 8 mg / mL PCA-Zn aqueous solution with deionized water respectively; (2) Under stirring conditions, 100 μL of TA solution and 100 μL of PCA-Zn solution (molar ratio of TA to PCA-Zn is 1:6) were added dropwise to 1.8 mL of PBS buffer (pH 7.5) at a rate of 20 drops per minute to obtain a mixed solution; then, a 300 W ultrasonic cell disruptor was used to sonicate the cells for 10 min under 0 ℃ ice-water bath conditions to obtain a suspension. (3) Centrifuge the suspension at 8000 rpm for 10 min, discard the supernatant, collect the precipitate, and wash it three times with deionized water to obtain the TA-Zn MPNs of this embodiment, which can also be called tannic acid-zinc nanoparticles (a solid powder).

[0072] For specific effect verification, TA-Zn MPNs can also be prepared into corresponding aqueous solutions for verification. And a comparison is made with a physical mixture of TA and PCA-Zn (denoted as TZ, or simply physical mixture; the molar ratio of TA to PCA-Zn is 1:6, without ultrasonic treatment, centrifugation and washing).

[0073] Example 2: Screening and optimization of TA-Zn MPNs preparation process

[0074] (1) Screening of reaction solvents

[0075] Keeping other parameters unchanged from Example 1, TA-Zn MPNs were prepared using PBS (phosphate buffer), methanol, and ethanol as solvents, respectively. The optimal solvent was selected by measuring particle size, PDI, and encapsulation efficiency. The results are as follows: Figure 1As shown, when the reaction solvent is PBS buffer, TA-Zn MPNs exhibit smaller particle size, lower particle density (PDI), and higher encapsulation efficiency. However, while the particle size of TA-Zn MPNs is similar in methanol and ethanol, the encapsulation efficiency of the nanoparticles is less than ideal. Furthermore, considering that using methanol and ethanol as reaction solvents may result in residual organic solvents that could cause skin irritation, this invention preferably uses PBS buffer as the reaction solvent for the preparation of TA-Zn MPNs.

[0076] (2) Screening of reaction solvent pH

[0077] Keeping other parameters unchanged from Example 1, TA-ZnMPNs were prepared using solvents with pH values ​​of 6.5, 7.0, 7.5, and 8.0, respectively. The optimal reaction pH was determined by measuring particle size, PDI, and encapsulation efficiency. The results are as follows: Figure 2 As shown, TA-Zn MPNs exhibit smaller particle size, lower particle density (PDI), and higher encapsulation efficiency at pH 7.5. However, in weakly acidic solvents, TA-Zn MPNs disintegrate under acidic conditions, releasing large amounts of polyphenols and metal ions, resulting in a lower encapsulation efficiency. Alkaline environments disrupt the pH balance of the skin surface, damaging the skin barrier and causing a series of adverse effects on the skin. Therefore, this invention preferably uses a neutral environment with a pH of 7.5 for the preparation of TA-Zn MPNs.

[0078] (3) Screening of the molar ratio (feed ratio) of TA and PCA-Zn

[0079] Keeping other parameters unchanged from Example 1, TA-Zn MPNs were prepared using TA and PCA-Zn molar ratios of 1:5, 1:6, 1:7, and 1:8, respectively. The optimal dosing ratio was screened by measuring particle size, PDI, and encapsulation efficiency. The results are as follows: Figure 3 As shown, when the molar ratio of TA to PCA-Zn is 1:6, TA-Zn MPNs exhibit smaller particle size, lower particle density (PDI), and higher encapsulation efficiency. Specifically, when the metal ion concentration is too low, the metal ions' ability to chelate polyphenols is insufficient, resulting in more TA remaining free in the aqueous dispersion, thus leading to a lower encapsulation efficiency. Conversely, when the metal ion concentration is too high, the ability of the metal ions to chelate polyphenols becomes saturated, resulting in no significant increase in encapsulation efficiency. Therefore, this invention preferably uses a TA to PCA-Zn molar ratio of 1:6 for the preparation of TA-Zn MPNs. After converting the molecular weight to mass concentration, this corresponds to adding 6.8 mg / mL of TA aqueous solution and 8 mg / mL of PCA-Zn aqueous solution at a volume ratio of 1:1.

[0080] (4) Screening of ultrasonic power

[0081] Keeping other parameters unchanged from Example 1, TA-Zn MPNs were prepared using ultrasonic powers of 200 W, 300 W, 400 W, and 500 W, respectively. The optimal ultrasonic power was determined by measuring particle size, PDI, and encapsulation efficiency. The results are as follows: Figure 4 As shown, TA-Zn MPNs exhibit smaller particle size, lower particle density (PDI), and higher encapsulation efficiency when the ultrasonic power is 300 W. Therefore, this invention preferably uses an ultrasonic power of 300 W to prepare TA-Zn MPNs.

[0082] Example 3 Characterization of TA-Zn MPNs

[0083] The TA-Zn MPNs powder obtained in Example 1 was characterized as follows: (1) Detection of hydrated particle size, PDI and Zeta potential The particle size, polydispersity index (PDI), and zeta potential of TA-Zn MPNs were determined using a laser particle size analyzer and a zeta potential analyzer. The results are as follows: Figure 5 As shown, the TA-Zn MPNs have a particle size of 129.93 ± 0.43 nm, a PDI of 0.116 ± 0.029, and a Zeta potential of -30.99 ± 1.39 mV.

[0084] (2) Observation using transmission electron microscopy and scanning electron microscopy

[0085] Add 10 μL of TA-Zn MPNs aqueous solution to a copper grid, ensuring the grid is completely covered. Let it stand for 3 minutes, then blot away excess liquid with absorbent paper. Repeat this process three times. Add 10 μL of 2% phosphotungstic acid staining solution to the copper grid, let it stand for 3–5 minutes, then blot away excess liquid. Irradiate under a heat lamp for 2–5 minutes until the copper grid is dry and can be detached from the filter paper. Image the grid using a transmission electron microscope. After fixation with platinum spraying, image the grid using a field emission scanning electron microscope. Results are as follows: Figure 6 As shown, TA-Zn MPNs are approximately spherical and have obvious structural features.

[0086] (3) Ultraviolet spectroscopy investigation

[0087] The TA-Zn MPNs aqueous solution was diluted to a suitable concentration, and a full-wavelength UV-Vis scan was performed at room temperature to obtain the UV-Vis absorption spectrum. The results are as follows: Figure 7 As shown, TA has a characteristic absorption peak at 276 nm, which is formed by the transition from π to π. The characteristic absorption bands of aromatic compounds are caused by the overlap of transitions and vibrations of the benzene ring. Compared with free TA, the characteristic peak of TA in TA-Zn MPNs red-shifts from 276 nm to 317 nm and the peak shape broadens, indicating that TA and PCA-Zn are successfully assembled.

[0088] (4) Fourier transform infrared spectroscopy investigation

[0089] Weigh out 3–5 mg of lyophilized TA, PCA-Zn, and TA-Zn MPNs powders respectively, add 300 mg of potassium bromide, grind them evenly under infrared lamp irradiation, compress them into thin tablets using a tablet press, and place them in an infrared spectrometer at 4000–500 cm⁻¹. -1 Scanning within the wavelength range, resolution 4 cm -1 The infrared absorption spectrum was obtained by scanning 16 times. The results are as follows: Figure 8 As shown, 3053-3695 cm -1 The absorption peak at 1614 cm⁻¹ is mainly attributed to OH. Compared to free PCA-Zn and TA, the OH peak in TA-Zn MPNs is broadened and weakened, possibly due to hydrogen bonding. -1 The peak at that location is attributed to COO - However, the absorption peak intensity is weakened in TA-Zn MPNs; 1450-1600 cm⁻¹ -1 The π bonds in the benzene ring skeleton at the site are slightly shifted due to the formation of coordinate bonds. Experimental results demonstrate the successful preparation of TA-Zn MPNs.

[0090] Example 4: In vitro stability study of TA-Zn MPNs

[0091] The aqueous solution of TA-Zn MPNs obtained in Example 1 was placed at 4 °C, 25 °C, and 45 °C for 28 days, respectively. Changes in the properties of the samples were observed, and the particle size, PDI, and retention rates of TA and Zn were measured on days 0, 7, 14, 21, and 28. The results are as follows: Figure 9 As shown, under storage conditions of 4 °C, the particle size, PDI, and retention rate of TA-Zn MPNs did not change significantly, indicating their good storage stability. Even after being stored at a high temperature of 45 °C for 28 days, the retention rates of tannic acid and zinc exceeded 90%, demonstrating their excellent high-temperature resistance. This solves the problems of poor stability and easy degradation of the active ingredients tannic acid and PCA-Zn, broadening the application range of this type of cosmetic raw material in formulations.

[0092] Example 5: In vitro antioxidant performance of TA-Zn MPNs

[0093] The TA-Zn MPNs obtained in Example 1 were characterized as follows: (1) Investigation of DPPH free radical scavenging ability DPPH (2-diphenyl hydrazy) is a stable free radical commonly used to evaluate the in vitro antioxidant activity of antioxidant components. DPPH free radicals possess a single electron and exhibit strong absorption at 517 nm, turning their alcoholic solution purple. In the presence of a free radical scavenger, the absorption gradually disappears due to the pairing of the DPPH free radical with its single electron. The degree of fading is quantitatively related to the number of electrons accepted, allowing for rapid quantitative analysis using a spectrophotometer. The determination of DPPH free radical scavenging rate is a widely used method for screening and evaluating the antioxidant capacity of antioxidants; a higher DPPH scavenging rate indicates stronger antioxidant capacity.

[0094] Accurately weigh 12 mg of DPPH, dissolve it in anhydrous ethanol, and prepare a DPPH ethanol solution with a concentration of 0.12 mg / mL. Dissolve and dilute the simple physical mixture of TA and PCA-Zn (TZ, with a molar ratio of TA to PCA-Zn of 1:6) and TA-Zn MPNs in deionized water to prepare sample solutions with concentrations of 10.0, 20.0, 30.0, 40.0, and 50.0 μg / mL.

[0095] Following the sample addition method in Table 1, each solution was added sequentially to the 96-well plate, shaken to mix thoroughly, and reacted at room temperature in the dark for 30 min before measuring the absorbance at 517 nm.

[0096] Table 1. Sample loading requirements for DPPH free radical scavenging experiment

[0097] Calculate the DPPH free radical scavenging rate for each group using the following formula: DPPH radical scavenging rate = (A0 - (A1 - A2)) / A0 × 100% Where A0 is the absorbance of the DPPH ethanol solution, A1 is the absorbance of the DPPH ethanol solution after reacting with the sample solution, and A2 is the absorbance of the sample solution itself.

[0098] Meanwhile, referring to the national standard GB-T 39100-2020 "Determination of Antioxidant Activity of Peptides: DPPH and ABTS Methods", the half-maximal scavenging capacity (EC50) of TZ and TA-Zn MPNs for DPPH free radicals was calculated. 50 EC 50 The smaller the value, the stronger the free radical scavenging ability of the substance and the better its antioxidant effect.

[0099] (2) Investigation of ABTS free radical scavenging ability

[0100] Accurately weigh ABTS and potassium persulfate (K₂S₂O₈), dissolve them in an appropriate amount of pure water to prepare ABTS stock solution with a concentration of 7.4 mmol / L and K₂S₂O₈ stock solution with a concentration of 2.6 mmol / L. Mix equal volumes of the two solutions and react in the dark for 12 hours. Dilute with ethanol to obtain ABTS ethanol solution. Dissolve and dilute TZ and TA-Zn MPNs separately in deionized water to prepare sample solutions with concentrations of 20.0, 40.0, 60.0, 80.0, and 100.0 μg / mL.

[0101] Following the sample addition method in Table 2, the reaction solution was added sequentially to the 96-well plate, shaken, mixed thoroughly, and allowed to react at room temperature in the dark for 6 min before the absorbance was measured at 734 nm.

[0102] Table 2 Sample loading requirements for ABTS free radical scavenging experiment

[0103] Calculate the ABTS radical scavenging rate for each group using the following formula, and also calculate the half-maximal scavenging amount (EC). 50 : ABTS radical scavenging rate = (A0 - A1) / A0 × 100% Where A0 is the absorbance of the ABTS ethanol solution, and A1 is the absorbance of the ABTS ethanol solution after reacting with the sample solution.

[0104] (3) Investigation of hydroxyl radical scavenging ability

[0105] Accurately weigh 0.1234 g of salicylic acid and dissolve it in 100 mL of anhydrous ethanol to prepare a salicylic acid-ethanol solution. Accurately weigh 0.2502 g of ferrous sulfate (FeSO4) and 99.26 mg of hydrogen peroxide (H2O2) and dissolve them separately in 100 mL of deionized water to prepare FeSO4 aqueous solution and H2O2 aqueous solution, respectively. Dissolve and dilute TZ and TA-Zn MPNs to prepare sample solutions with concentrations of 40.0, 60.0, 80.0, 100.0, 120.0, and 140.0 μg / mL, respectively.

[0106] Add the reagents sequentially to the 96-well plate according to the sample addition method in Table 3, mix well, react at 37°C in the dark for 15 min, and then measure the absorbance at 510 nm.

[0107] Table 3 Sample loading requirements for hydroxyl radical scavenging experiments

[0108] Calculate the hydroxyl radical scavenging rate for each group using the following formula, and also calculate the half-maximal scavenging (EC50) value. 50 : Hydroxyl radical scavenging rate (%) = (1-(A) X -A X0 ) / A0) 100% Where A0 is the absorbance of the blank group, A X A1 represents the absorbance of the experimental group, and A2 represents the absorbance of the damaged group (without the colorimetric reagent H2O2).

[0109] The above test results are as follows Figure 10 As shown, all experimental samples exhibited excellent DPPH, ABTS, and hydroxyl radical scavenging abilities, and all showed a concentration-dependent increasing trend. The EC50 of TZ and TA-Zn MPNs on DPPH radicals... 50 The EC50 values ​​for ABTS radicals were 17.01 ± 0.52 μg / mL and 12.28 ± 1.34 μg / mL, respectively. 50 The EC50 values ​​for hydroxyl radicals were 43.62 ± 1.63 μg / mL and 37.35 ± 3.41 μg / mL, respectively. 50 The concentrations were 111.60 ± 4.20 μg / mL and 74.94 ± 4.37 μg / mL, respectively. EC 50 The smaller the value, the stronger the free radical scavenging ability of the substance and the better its antioxidant effect. Experimental results show that compared to the physical mixture of TA and PCA-Zn, supramolecularly assembled tannic acid-PCA zinc nanoparticles (TA-Zn MPNs) can significantly improve the scavenging rates of DPPH, ABTS, and hydroxyl radicals, exhibiting significant antioxidant properties. This indicates that using supramolecular technology to prepare TA and PAC-Zn into nanoparticles is beneficial, and the antioxidant effect is superior to that of a simple physical mixture of the two, representing a significant advancement.

[0110] Example 6: In vitro transdermal performance of TA-Zn MPNs

[0111] The TA-Zn MPNs obtained in Example 1 were characterized as follows: The transdermal penetration and intradermal retention of TZ and TA-Zn MPNs were investigated using the Retop RT800 automated sampling transdermal diffusion system. Rat skin was hydrated with physiological saline at room temperature for 20 min, and residual moisture was blotted with filter paper. The skin was then cut into 1.5 cm diameter circles using a mold, with the stratum corneum facing upwards, and precisely installed in the diffusion chamber. Physiological saline was injected into the receiving chamber using a sampling needle, and residual air bubbles were removed by gently tapping the chamber wall at a 45-degree angle. The water bath temperature was set to (32 ± 1) °C, and the magnetic stirring speed was set to 400 rpm. 1 mL of TZ and TA-Zn MPNs sample solutions were added to the supply chamber, and three parallel experiments were set up. At 0.5, 1, 2, 4, 6, 8, 10, 12, and 24 h after sample addition, 1.5 mL of the receiving solution was drawn into centrifuge tubes using a sampling needle, and 1.5 mL of physiological saline was added to the receiving chamber simultaneously. The cumulative permeation (Q) at different time points was calculated using the following formula. n ).

[0112] Q n (μg / cm 2 ) =

[0113] Among them, C n Let V0 be the concentration of the sample in the receiving liquid during the nth sampling, and C be the total volume of the receiving liquid in the receiving cell. i V represents the concentration of the sample in the receiving liquid during the i-th sampling. n The volume of receiving fluid taken at each time point, where S is the effective skin penetration area.

[0114] After sampling, skin was removed from the diffusion cell and the surface was washed with physiological saline to remove any remaining sample solution. The surface moisture was blotted dry with filter paper, and the skin was shredded and placed in a grinding tube. A certain volume of physiological saline was added, and the tube was placed in a cryogenic abrasive apparatus. The frequency was adjusted to 65 Hz, with a grinding time of 90 s per cycle, 10 s intervals, and grinding was repeated 4-5 times until the skin tissue was fully broken down. The resulting abrasive solution was centrifuged at 10,000 rpm for 30 min, and the supernatant was used to determine the sample concentration. The intradermal retention volume (X) after 24 h of penetration was calculated using the following formula.

[0115] X (μg / cm 2 ) =

[0116] Among them, C r V represents the concentration of the active ingredient measured in the skin homogenate. r Where S is the solvent volume and S is the effective penetration area.

[0117] Experimental results are as follows Figure 11As shown, the cumulative permeation and transdermal retention of TA and Zn in TA-Zn MPNs within 24 h were significantly higher than those in the physical mixture of the two raw materials. The results indicate that TA-Zn MPNs can effectively penetrate the stratum corneum barrier, increase the transdermal permeation and intradermal retention of TA and PCA-Zn, and significantly improve the transdermal permeability of the active ingredients.

[0118] Example 7 Evaluation of the cell protective and repair effects of TA-Zn MPNs

[0119] The TA-Zn MPNs obtained in Example 1 were characterized as follows: (1) Protective effect of TA-Zn MPNs against oxidative damage in HaCaT cells Human immortalized keratinocytes (HaCaT) were seeded at a density of 8000 cells / well in 96-well plates containing complete culture medium. After cell attachment, the old culture medium in the 96-well plates was discarded, and the cells were thoroughly washed with PBS buffer and pre-protected with different concentrations of TA-Zn MPNs solution for 12 h. A model group and a control group were set up, with 5 replicates in each group. The model group (H2O2 group) was operated on the same basis as the experimental group except that no TA-Zn MPNs solution was added for pre-protection. The control group only had culture medium added and was not damaged with H2O2 solution (the cell viability in the control group was 100%, and the cell viability in the experimental and model groups was calculated relative to the control group). After incubation for 12 h, the culture medium in the plates was discarded, the cells were thoroughly washed with PBS buffer, and damaged with H2O2 solution for 4 h. Cell viability was calculated using the MTT assay. Results are shown below. Figure 12 As shown, the survival rate of cells in the experimental group increased significantly after pre-protection with different concentrations of TA-Zn MPNs. Treatment with 20 μg / mL of nanoparticles could increase cell viability to over 80%, indicating that TA-Zn MPNs have a significant protective effect on HaCaT cells damaged by H2O2 oxidation.

[0120] (2) Effects of TA-Zn MPNs on the migration ability of HaCaT cells

[0121] HaCaT cells in the logarithmic growth phase were harvested at a concentration of 2 × 10⁻⁶. 5Cells were seeded at a density of [number] cells / well in 6-well plates containing complete culture medium and incubated for 24 h. After confirming complete cell adhesion under a microscope, vertical scratches were made using a sterilized pipette tip to create uniformly wide cell damage areas. Cells were gently washed with PBS buffer to remove detached cells and debris, and initial scratch images were acquired under a microscope. Serum-free culture medium and serum-free culture medium containing TZ and TA-Zn MPNs were added separately, and the plates were returned to the incubator for further incubation. Cells were removed at 6, 12, and 24 h, and cell migration was observed and a series of images were acquired under the same field of view. Results are as follows: Figure 13 As shown, the migration ability of HaCaT cells in each experimental group increased in a time-dependent manner. Compared with the control group and the simple physical mixture group, TA-Zn MPNs can significantly promote the growth and migration of HaCaT cells, demonstrating excellent repair efficacy.

[0122] (3) Protective effect of TA-Zn MPNs against UVB damage in L929 cells

[0123] Mouse fibroblasts (L929) were seeded at a density of 8000 cells / well in 96-well plates containing complete culture medium. After cell attachment, the old culture medium in the 96-well plates was discarded, and the cells were thoroughly washed with PBS buffer and pre-protected with TA-ZnMPNs solutions of different concentrations for 12 h. A model group and a control group were set up, with 5 replicates per group. The model group (UVB group) was operated on the same as the experimental group except that TA-ZnMPNs solution was not used for pre-protection. The control group only received culture medium and was not subjected to UVB damage (cell viability in the control group was 100%, and cell viability in the experimental and model groups was calculated relative to the control group). After incubation for 12 h, the culture medium in the plates was discarded, and the cells were thoroughly washed with PBS buffer at 240 mJ / cm². 2 Cells were cultured in serum-free medium for 24 h after UVB damage, and cell viability was calculated using the MTT assay. Results are as follows: Figure 14 As shown, the survival rate of cells in the experimental group increased significantly after pre-protection with different concentrations of TA-Zn MPNs. Treatment with 30 μg / mL of nanoparticles could increase cell viability to over 80%, indicating that TA-Zn MPNs have a significant protective effect on L929 cells damaged by UVB and can effectively resist photoaging caused by UVB at low concentrations.

[0124] Example 8: Evaluation of the oil-controlling efficacy of TA-Zn MPNs

[0125] Sebum is produced by sebaceous gland cells in the dermis and then secreted onto the skin's surface. Studies have shown that human sebum is a mixture of various components, mainly phospholipids, triglycerides, fatty acids, squalene, cholesterol esters, small amounts of cholesterol, and diglycerides. Oily skin is caused by excessive sebum secretion, resulting in shiny skin and an unpleasant appearance and feel. Excessive sebum distributed in the epidermis can also easily cause inflammation, attract dust, accumulate and clog pores, leading to rough stratum corneum and ultimately acne.

[0126] 5α-reductase is a key enzyme in the metabolism of androgens in the skin, its main function being to catalyze the conversion of testosterone to dihydrotestosterone (DHT). When DHT enters the sebaceous glands and accumulates to a certain level, it can cause sebaceous gland cell lesions, leading to excessive sebum secretion. Therefore, reducing or inhibiting 5α-reductase activity can effectively reduce sebum secretion.

[0127] Oil Red O staining utilizes the binding of Oil Red O dye to lipids, turning them red, which facilitates microscopic observation and quantitative analysis. By detecting intracellular lipid content using Oil Red O staining, the oil-controlling effect of a sample on human sebaceous gland cells can be assessed.

[0128] Specifically, the following oil control characterization was performed on the TA-Zn MPNs obtained in Example 1: (1) Experimental methods 1.1 5α-Reductase Inhibition Experiment 96-well plate loading: The experiment included a standard group, a sample group (TA-Zn MPNs, 0.2%), a control group (a simple physical mixture of 0.1% TA and 0.1% PCA-Zn), and a blank control group (no sample or HRP enzyme-labeled reagent added; all other steps were the same). Each experimental group was run in triplicate. The test was performed according to the kit instructions. 5α-reductase inhibition rate (%) = (OD450 standard wells - OD450 sample wells) / (OD450 standard wells - OD450 background wells) × 100%.

[0129] 1.2 Oil Red O Staining Experiment

[0130] Human sebaceous gland cells at 5% CO2, 37 Cells were cultured under C conditions. When the cells reached 60-70% confluence, they were digested with trypsin and seeded into 24-well plates. The plates were then incubated for 24 hours until cell confluence. Cells were washed with PBS, and then divided into groups for sample loading. For the positive group, 1 mL of culture medium containing 0.01 mmol / L isotretinoin was added to each well; for the control group, 1 mL of culture medium containing a simple physical mixture of 50 ppm tannic acid and 50 ppm PCA-Zn was added to each well; and for the sample group, 1 mL of culture medium containing 100 ppm TA-Zn MPNs was added to each well.

[0131] After returning to the incubator and culturing for another 24 h, the DME medium was discarded, and 4% paraformaldehyde solution was added for fixation at room temperature for 15 min. The excess solution was discarded, and 0.5% Oil Red O solution was added for staining at room temperature for 15 min. The staining was then rinsed with distilled water until no red residue remained, and the lipid content was observed by microscopic imaging.

[0132] ImageJ was used to analyze the images and calculate the IOD of the stained regions, with the IOD of the control group set at 100%. The relative lipid content (%) was calculated as: IOD of each group / IOD of the control group (mean × 100%).

[0133] (2) Experimental results

[0134] The results of the 5α-reductase inhibition rate of the samples are shown in Table 4, and the calculated lipid inhibition rate is shown in Table 5. Compared with the blank control group, P <0.01, P <0.001, P <0.0001.

[0135] Table 4. Experimental results of 5α-reductase inhibition rate

[0136] Table 5. Results of lipid inhibition rate experiment

[0137] As shown in Table 4, the TA-Zn MPNs sample group exhibited a significant 5α-reductase inhibitory effect, with an inhibition rate of 56.71% at a concentration of 0.2%, demonstrating oil-controlling efficacy. In contrast, the simple physical mixture of tannic acid and PCA-Zn at the same concentration in the control group showed an inhibition rate of only 24.45% for 5α-reductase, far lower than that of TA-Zn MPNs. Table 5 shows that the lipid production of sebaceous gland cells treated with TA-Zn MPNs was significantly reduced, with a lipid inhibition rate as high as 61.24%, indicating a highly significant inhibitory effect on lipid synthesis in human sebaceous gland cells at this tested concentration, thus providing a certain degree of oil-controlling efficacy. In contrast, the simple physical mixture of tannic acid and PCA-Zn at the same concentration in the control group showed an inhibition rate of only 28.16% for lipids. This indicates that assembling tannic acid and PCA-Zn into nanoparticles using supramolecular technology can produce a powerful effect on regulating sebum secretion, superior to the physical mixture of the two raw material compounds. These supramolecular nanoparticles have a low effective concentration and significant effect, demonstrating promising application prospects in skincare products.

[0138] Example 9: Preparation method of essence based on supramolecular assembly of tannic acid-zinc nanoparticles

[0139] The TA-Zn MPNs obtained in Example 1 were formulated into an essence according to the following formula: 1% TA-Zn MPNs, 3% Glycerin, 3% Glyceryl Ether-26, 2% 1,3-Butanediol, 0.3% Sodium Hyaluronate, 0.1% Xanthan Gum, 0.1% Carbomer, 0.5% Methyl Gluten Ether-20, 0.5% PEG-40 Hydrogenated Castor Oil, 0.2% Ascorbic Acid, 0.2% Tocopheryl Acetate, 0.1% Ceramide NP, 1% Phenoxyethanol, 0.5% 1,2-Hexanediol, 0.5% Fragrance, balance deionized water.

[0140] The corresponding preparation method includes the following steps: (1) According to the formula ratio, xanthan gum and carbomer are added to an appropriate amount of deionized water, heated to 80 ℃, mixed and stirred evenly, and then cooled to 40 ℃; glycerol, glycerol polyether-26, 1,3-butanediol, sodium hyaluronate, methyl glucetol polyether-20 and PEG-40 hydrogenated castor oil are added, mixed and stirred evenly, homogenized using a high pressure homogenizer for 3 min, and cooled to room temperature as mixture A; (2) According to the formula ratio, add TA-Zn MPNs, ascorbic acid, tocopheryl acetate, ceramide NP, phenoxyethanol, 1,2-hexanediol and fragrance to deionized water, mix and stir evenly to form mixture B; (3) Add mixture B to mixture A and homogenize using a high-pressure homogenizer for 3 min to obtain the final product.

[0141] The preparation process of this serum is simple, mild, and highly reproducible, requiring no organic solvents and conforming to the principles of green chemistry.

[0142] Example 10: In vivo safety evaluation of an essence based on supramolecularly assembled tannic acid-zinc nanoparticles

[0143] The safety of the serum in Example 9 was investigated using the repeated skin irritation test method in the "Cosmetic Safety Technical Specifications (2015 Edition)". Five male ICR mice (N=5) were used and acclimatized for one week. Before the experiment, the hair on both sides of the spine on the back of the mice was shaved, with a shaved area of ​​2 cm × 3 cm. 0.5 g of the test serum was applied to the left side of the skin, while physiological saline was applied to the right side as a control. Application was performed once daily for 14 consecutive days. Before each application, the hair was shaved, and any remaining test substance was washed off the application site with distilled water. One hour after application, the skin condition on both sides of the mice was observed, and the skin condition on both sides was scored according to Table 6.

[0144] Table 6 Skin Irritation Response Scores

[0145] The results are as follows Figure 15 As shown, the mice did not exhibit any abnormal skin reactions such as erythema or edema during the experimental period, and the average score of skin irritation intensity was 0, indicating that the essence has no skin irritation and good skin safety.

[0146] Example 11 Evaluation of the anti-photoaging efficacy of an essence based on supramolecularly assembled tannic acid-zinc nanoparticles

[0147] The essence obtained in Example 9 was characterized as follows: (1) Construction of a UVB-induced mouse skin photoaging model Hair was removed from the backs of 5 mice (N=5), with a total hair removal area of ​​approximately 2 × 3 cm. 2 Mice were placed in an ultraviolet chamber for UVB irradiation. The irradiation method was as follows: during weeks 1-2, the UV radiation dose was 75 mJ / cm². 2 During weeks 3-4, the UV radiation dose was 150 mJ / cm². 2 During weeks 5-6, the UV radiation dose was 225 mJ / cm². 2 During weeks 7-8, the UV radiation dose was 300 mJ / cm². 2The experiment lasted for 8 weeks, during which UV irradiation was performed every other day. During the experimental period, mice in the TA-Zn MPNs essence group (also known as the tannic acid-zinc nanoparticle essence group), the TA and PCA-Zn simple physical mixture essence group (also known as the physical mixture essence group; TA and PCA-Zn were mixed in a molar ratio of 1:6, which translates to a mass ratio of 0.46% TA and 0.54% PCA-Zn, i.e., the total mass of the two was 1%), and the essence matrix group (also known as the blank matrix group; i.e., the essence formula of Example 9 without TA-Zn MPNs) were applied with 0.5 g of the corresponding sample daily. After 1 hour of free activity, they were irradiated with UVB according to the modeling requirements. Mice in the blank group were only applied with 0.5 g of physiological saline without UVB irradiation, while mice in the model group were only applied with 0.5 g of physiological saline and then irradiated with UVB.

[0148] (2) Detection of skin moisture content in mice

[0149] The skin moisture content of mice was measured using a Corneometer CM 825 skin moisture meter. The results are as follows: Figure 16 As shown, the skin moisture content of the model group mice was significantly lower than that of the control group. This is because long-term UVB irradiation in the model group mice damaged the TEWL barrier in their skin, thereby weakening the hydration of keratinocytes and significantly reducing skin moisture content. The serum group, by applying the corresponding serum, significantly improved the decrease in skin moisture content caused by long-term UVB irradiation, allowing the hydration of keratinocytes to proceed normally. Compared with the simple physical mixture serum group of TA and PCA-Zn, the TA-Zn MPNs serum group showed a significant increase in moisture content, indicating that TA-Zn MPNs can exert good moisturizing effects and has a synergistic effect in improving skin moisture content.

[0150] (3) Histopathological examination of mouse skin tissue

[0151] Histopathological examination of mouse skin was performed using H&E staining. Skin tissue was harvested from the back of mice, subcutaneous fat was removed, and the skin surface was rinsed with PBS buffer to remove impurities. A 2 × 2 cm section was cut. 2 Skin samples of varying sizes were fixed in 4% paraformaldehyde, ensuring the skin remained flat and uncurled during fixation. The fixed skin tissue was then embedded in paraffin, sectioned, and stained with hematoxylin and eosin solutions. Finally, the sections were scanned using a tissue scanner to examine the skin condition of different groups of mice. Results are as follows: Figure 17As shown, the skin tissue structure of mice in the blank group was intact, with no abnormal epidermal proliferation, while the skin of mice in the model group showed excessive keratinization, significantly increased epidermal thickness, and disordered dermal tissue structure, consistent with the characteristics of a photoaging model. Compared with the model group, the serum matrix group showed no significant changes, indicating that the serum matrix had no effect on improving photoaged skin. However, the epidermal thickness of mice in the TA-Zn MPNs serum group was significantly reduced, and the skin tissue was closer to that of normal mouse skin, indicating that the serum with TA-Zn MPNs as the active ingredient can effectively improve skin aging caused by long-term UVB exposure, and its effect is superior to a simple physical mixture of the two ingredients.

[0152] (4) Levels of inflammatory factors in mouse skin tissue

[0153] A 0.5 g sample of mouse back skin tissue was accurately weighed using a precision electronic balance. Subcutaneous fat tissue was carefully removed using sterile surgical forceps, and the sample was then cut into small fragments using ophthalmic scissors. The processed tissue fragments were transferred to pre-chilled grinding tubes, and 5 mL of pre-chilled tissue extraction buffer was added. Four magnetic beads were placed in each grinding tube, which was then placed in a cryogenic homogenizer. The homogenization temperature was set to 0°C, the grinding frequency to 65 Hz, and the grinding time was 90 s per cycle with 10 s intervals. This process was repeated 4-5 times until the skin tissue was fully broken down, yielding a skin tissue homogenate with a concentration of 0.1 mg / mL. The prepared skin tissue homogenate was transferred to a pre-chilled high-speed refrigerated centrifuge and centrifuged at 10,000 rpm for 30 min at 4°C. After centrifugation, the supernatant was collected, and the levels of IL-1β, IL-6, and TNF-α were measured according to the ELISA kit instructions. The results are as follows: Figure 18 As shown, compared with the blank group, the levels of relevant inflammatory factors in the skin tissue of the model group mice were significantly increased, indicating that the model group mice experienced an inflammatory response in their skin under photoaging conditions. Compared with the simple physical mixture of TA and PCA-Zn essence, the TA-Zn MPNs essence group could significantly reduce the levels of inflammatory factors in the mouse skin, indicating that preparing TA and PCA-Zn into supramolecular nanoparticles is beneficial and has a synergistic effect. TA-Zn MPNs can effectively inhibit the inflammatory response induced by UVB irradiation and have a very significant soothing effect.

[0154] (5) Extracellular matrix levels in mouse skin tissue

[0155] The supernatant of skin tissue homogenate was collected and the contents of type I collagen (Col I) and matrix metalloproteinase 1 (MMP-1) in the supernatant were determined according to the ELISA kit instructions. Results are as follows: Figure 19As shown, compared with the control group, the Col I content in the skin tissue of the model group mice was significantly reduced and the MMP-1 level was significantly increased. The model group mice also showed severe collagen loss in their skin, indicating that the mouse skin photoaging model was successfully established. Compared with the simple physical mixture essence group, the TA-Zn MPNs essence group significantly increased collagen content and decreased MMP-1 levels in mouse skin, indicating that TA-Zn MPNs can effectively improve collagen loss caused by UVB irradiation and has an anti-photoaging effect, thus possessing significant anti-aging efficacy and great potential in the cosmetics field.

Claims

1. A supramolecularly assembled tannic acid-zinc nanoparticle, characterized in that, The supramolecularly assembled tannic acid-zinc nanoparticles are aggregate structures formed by non-covalent interactions between tannic acid and zinc pyrrolidone carboxylate.

2. The supramolecularly assembled tannic acid-zinc nanoparticles as described in claim 1, characterized in that, The supramolecularly assembled tannic acid-zinc nanoparticles satisfy one or more of the following conditions: (1) The non-covalent interactions include one or more of hydrogen bonds, π-π stacking, and van der Waals forces; (2) The molar ratio of tannic acid and zinc pyrrolidone carboxylate is 1:(5-8).

3. The supramolecularly assembled tannic acid-zinc nanoparticles as described in claim 1 or 2, characterized in that, The supramolecularly assembled tannic acid-zinc nanoparticles satisfy one or more of the following conditions: (1) The molar ratio of tannic acid and zinc pyrrolidone carboxylate is 1:(6-7); (2) The hydrated particle size of the supramolecularly assembled tannic acid-zinc nanoparticles is 110-150 nm; (3) The PDI of the supramolecularly assembled tannic acid-zinc nanoparticles is 0.05-0.20; (4) The Zeta potential of the supramolecularly assembled tannic acid-zinc nanoparticles is -25 to -35 mV.

4. A method for preparing supramolecularly assembled tannic acid-zinc nanoparticles, characterized in that, The method for preparing the supramolecularly assembled tannic acid-zinc nanoparticles includes the following steps: A mixed solution consisting of tannic acid, zinc pyrrolidone carboxylate, and a solvent was subjected to ultrasonic treatment.

5. The method for preparing supramolecularly assembled tannic acid-zinc nanoparticles as described in claim 4, characterized in that, The method for preparing supramolecularly assembled tannic acid-zinc nanoparticles satisfies one or more of the following conditions: (1) The molar ratio of tannic acid and zinc pyrrolidone carboxylate is 1:(5-8); (2) The solvent is PBS buffer; (3) The pH of the solvent is 6.5-8.0; (4) The power of the ultrasonic treatment is 200-500W; (5) The duration of the ultrasonic treatment is 5-20 min; (6) The ultrasonic treatment is performed in an ice-water bath; (7) The ultrasonic treatment is performed in an ultrasonic cell disruptor; (8) The tannic acid and zinc pyrrolidone carboxylate are each added independently in the form of aqueous solution to the solvent, and then mixed to obtain the mixed solution; (9) The ultrasonic treatment also includes centrifugation to collect the precipitate and washing.

6. The method for preparing supramolecularly assembled tannic acid-zinc nanoparticles as described in claim 5, characterized in that, The method for preparing supramolecularly assembled tannic acid-zinc nanoparticles satisfies one or more of the following conditions: (1) The molar ratio of tannic acid and zinc pyrrolidone carboxylate is 1:(6-7); (2) The pH of the solvent is 7.0-7.5; (3) The frequency of the ultrasonic treatment is 300-400W; (4) The aqueous solution of tannic acid and the aqueous solution of zinc pyrrolidone carboxylate are each added to the solvent independently by dropwise addition; (5) The centrifuge speed is 6000-10000 rpm; (6) The centrifugation time is 5-20 min; (7) The washing is performed with deionized water.

7. A supramolecularly assembled tannic acid-zinc nanoparticle, characterized in that, The supramolecularly assembled tannic acid-zinc nanoparticles are prepared by the method for preparing supramolecularly assembled tannic acid-zinc nanoparticles as described in any one of claims 4-6.

8. The application of supramolecularly assembled tannic acid-zinc nanoparticles as described in any one of claims 1-3 and 7 in the preparation of cosmetics.

9. The application as described in claim 8, characterized in that, The cosmetic product possesses one or more of the following effects: anti-photoaging, oil control, anti-oxidation, anti-inflammation, anti-aging, soothing, skin cell protection, skin cell repair, and moisturizing.

10. The application as described in claim 8, characterized in that, The cosmetic product meets one or more of the following conditions: (1) The cosmetic product is selected from one or more of the following: facial mask, gel, serum, essence, and cream; (2) In the cosmetic, the content of the supramolecular assembled tannic acid-zinc nanoparticles is 0.2wt%-1.0wt%.

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