A phenolic acid-modified attapulgite composite sunscreen agent, a preparation method and application thereof, and a pickering sunscreen emulsion

Abstract

This invention provides a phenolic acid-modified attapulgite composite sunscreen agent, its preparation method, and applications, as well as a Pickering sunscreen lotion, belonging to the field of cosmetic technology. The method of this invention includes acid treatment of attapulgite, surfactant modification, loading of phenolic acid biomolecules, and hydrophobic modification. Using modified attapulgite as a carrier, this invention loads phenolic acid biomolecules through electrostatic adsorption to construct a composite synergistic system, and further modifies the surface with hydrophobicity to obtain a composite sunscreen agent with high stability and excellent sun protection performance. The sunscreen agent prepared by this invention combines physical shielding and biological protection functions, exhibiting excellent UV absorption capacity, good dispersibility, skin compatibility, and a pleasant feel on the skin. It solves the problems of nanoparticle aggregation, whitening, and poor photostability in existing sunscreen products, making it suitable for the cosmetic sunscreen field. It can achieve broad-spectrum UVA / UVB protection, antioxidant properties, and soothing repair, showing broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of cosmetic technology, and in particular to a phenolic acid-modified attapulgite composite sunscreen agent, its preparation method and application, and Pickering sunscreen lotion. Background Technology

[0002] Ultraviolet (UV) radiation from sunlight, as a persistent external damaging factor, poses a systemic threat to human skin health and is a key factor in inducing sunburn and skin cancer. Ultraviolet radiation can be divided into long-wave UVA (315-400 nm), medium-wave UVB (280-315 nm), and short-wave UVC (200-280 nm). UVC is usually blocked by the ozone layer and rarely reaches human skin. UVB is the most biologically active component of sunlight, with phototoxicity approximately 1000 times that of UVA, and is a major factor in inducing acute skin damage such as erythema and sunburn cell formation. UVB penetrates to the dermis, causing various skin damages. Furthermore, UVB stimulates the proliferation of keratinocytes and causes photooxidative damage to various skin cells, including keratinocytes and melanocytes. UVA penetrates much deeper than UVB, reaching the dermis and even affecting all skin layers. Although UVA radiation energy is low, its effects are cumulative, mainly manifesting as accelerated skin aging and structural damage.

[0003] Sunscreen cosmetics contain sunscreen agents that block or absorb ultraviolet (UV) rays to protect the skin from UV damage, aiming to reduce health risks such as sunburn, skin cancer, and photoaging caused by long-term and cumulative sun exposure. Sunscreen agents can be divided into organic, inorganic, and biological sunscreen agents. Organic sunscreen agents, also known as chemical sunscreen agents, mainly contain aromatic hydrocarbons or other organic compounds rich in electron bonds. Their photoprotective mechanism is to quickly absorb UV rays and convert them into heat, thus preventing them from acting on the skin. However, their application still faces difficulties. Organic active ingredients can cause skin allergies and are prone to skin penetration problems. In addition, some organic sunscreen agents can damage marine ecosystems and have been banned. Inorganic sunscreen agents, also known as physical sunscreen agents, are mainly composed of metal oxide particles such as titanium dioxide and zinc oxide. Their photoprotective mechanism is to form a physical protective film that reflects UV rays, thereby achieving broad-spectrum protection. In applications, the coverage of large-particle metal oxides can easily lead to skin whitening, while nano-sized inorganic particles pose risks of particle aggregation, formulation layering, and potential photocatalytic toxicity. Bio-sunscreens refer to active ingredients extracted from natural products or obtained through biotechnology. Their mechanisms of action rely on biological pathways, such as scavenging free radicals, inhibiting inflammatory responses, and repairing photo-oxidative damage, thereby enhancing the skin's overall defense against ultraviolet radiation. Many natural extracts have the potential to act as sunscreens, but the mechanisms of action and effects vary considerably among different natural products. Studies have shown that many plant natural products exhibit significant bioactivity in skin protection. Compounds such as aloe vera extract, ginsenosides, curcumin, epicatechin, asiaticoside, genipin I, magnolol, gallic acid, hydroxyaniline, hydroxycinnamic acid, and hydroxybenzoic acid have the ability to scavenge reactive oxygen species (ROS), effectively reducing oxidative stress damage to skin cells. These ingredients maintain skin hydration by enhancing the skin barrier function and reducing transepidermal water loss (TEWL). In addition, some plant polyphenols exhibit ultraviolet absorption properties. When combined with physical sunscreens, their sun protection factor (SPF) can reach 15 or higher, which helps to reduce photoaging damage caused by ultraviolet radiation, including collagen degradation and wrinkle formation, thereby improving skin texture and appearance.

[0004] Inorganic nanocarriers typically refer to nanomaterials with large specific surface areas, such as halloysite nanotubes, carbon nanotubes, graphene nanosheets, and mesoporous silica. In the field of UV-shielding composite materials, inorganic nanocarriers can not only provide favorable sites for the coating of UV-resistant nanoparticles, but also inhibit severe agglomeration of nanoparticles, thereby improving the UV-shielding efficiency of the composite material.

[0005] Attapulgite, also known as magnesium silicate, was included in the new cosmetic raw material catalog in 2021. It is a natural, layered, porous, fibrous, hydrous magnesium aluminum silicate clay mineral with a rod-like crystal structure. Due to its abundant natural resources, lack of pollution, strong biocompatibility, opacity, and astringency, it exhibits excellent skin contact safety. Furthermore, its rich nanoscale pores and grooves can adsorb and confine organic molecules on the mineral's surface and within its pore and groove structure, effectively reducing photochemical oxidation and preventing the formation of toxic byproducts, thereby improving the stability, safety, and effectiveness of sunscreen products. Modified attapulgite combined with biomolecules holds great potential in the sunscreen field. Modified attapulgite can not only directly participate in sun protection as a physical barrier agent but also act as a functional carrier and synergist, enhancing sunscreen efficacy while improving formulation safety, thus possessing broad applications.

[0006] Currently, some sunscreen products use attapulgite as a carrier or excipient, but they mainly rely on physical sunscreens such as zinc oxide and titanium dioxide, still facing issues such as nanoparticle safety risks and noticeable whitening. Furthermore, existing attapulgite products incorporating natural plant ingredients suffer from photodegradability and insufficient stability, failing to meet consumers' multiple demands for a lightweight feel, safety, non-irritation, and long-lasting protection. For example, Chinese patent CN110897955A discloses a sunscreen composition, its preparation method, and its application, which uses modified attapulgite, expanding its application in cosmetics. However, it only focuses on the film-forming properties of attapulgite, resulting in its overall effectiveness in a composite sunscreen system not being realized, and the operation process is relatively complex, making large-scale production difficult. Chinese patent CN115317384A proposes using attapulgite as a carrier to achieve particle loading, providing feasibility for the application of attapulgite, but it mainly loads zinc oxide and titanium dioxide, resulting in insufficient loading for the application of natural organic extracts and limited application prospects. Summary of the Invention

[0007] The purpose of this invention is to provide a phenolic acid-modified attapulgite composite sunscreen agent, its preparation method and application, and Pickering sunscreen emulsion. The phenolic acid-modified attapulgite composite sunscreen agent has the advantages of high efficiency, broad-spectrum sun protection, antioxidant protection and high safety.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a phenolic acid-modified attapulgite composite sunscreen, comprising the following steps: Attapulgite is mixed with an acid solution and subjected to acid treatment to obtain acidified attapulgite. The acidified attapulgite, water, and surfactant are mixed to perform the first modification, resulting in modified attapulgite. The modified attapulgite was mixed with phenolic acid biomolecules and a solvent, and the pH was adjusted to the desired level to obtain an attapulgite-loaded phenolic acid complex. The surface hydrophobic modifier was mixed with an alcohol solution and hydrolyzed to obtain the hydrolysis product. The attapulgite-loaded phenolic acid complex was mixed with the hydrolysis product and subjected to a second modification to obtain a phenolic acid-modified attapulgite composite sunscreen.

[0009] Preferably, the acid solution includes one or more of hydrochloric acid, sulfuric acid, acetic acid, carbonic acid, and dilute nitric acid; the concentration of the acid solution is 0.3~1.7 mol / L; and the acid treatment temperature is 80~150 ℃, and the time is 5~48 h.

[0010] Preferably, the surfactant includes one or more of cocamidopropyl betaine, lauryl betaine, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, and sulfobetaine; The mass ratio of the surfactant to acidified attapulgite is 0.1:1 to 5:1; the first modification temperature is 30 to 100 °C, and the time is 10 to 30 h.

[0011] Preferably, the phenolic acid biomolecules include one or more of caffeic acid, gallic acid, ferulic acid, p-coumaric acid, ellagic acid, and p-hydroxybenzoic acid; the mass ratio of the modified attapulgite to the phenolic acid biomolecules is 0.5:1 to 5:1. Adjust the pH to 2-5, the temperature of the compounding process is 10-50 ℃, the time is 60-180 min, and the stirring speed is 200-700 rpm.

[0012] Preferably, the surface hydrophobic modifier comprises one or more of dodecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, vinyltriethoxysilane, and dodecyltriethoxysilane. The alcohol solution includes an ethanol solution with a concentration of 50-90 wt.%; the hydrolysis temperature is 10-50 °C and the time is 1-10 h.

[0013] Preferably, the ratio of the surface hydrophobic modifier to the attapulgite-supported phenolic acid composite is (10~100) μL:(2~5) g; the temperature of the second modification is 10~100 ℃, and the time is 2~12 h.

[0014] This invention provides a phenolic acid-modified attapulgite composite sunscreen prepared by the preparation method described in the above technical solution.

[0015] This invention provides the application of the phenolic acid-modified attapulgite composite sunscreen agent described above in the field of cosmetics, wherein the cosmetics include sunscreen lotion, sunscreen cream, sunscreen gel or sunscreen spray.

[0016] This invention provides a Pickering sunscreen lotion comprising the phenolic acid-modified attapulgite composite sunscreen agent described in the above technical solution, an aqueous phase, an oil phase, and a preservative.

[0017] Preferably, the Pickering sunscreen lotion comprises the following components by weight percentage: 8-12% complex sunscreen agent, 3-6% glycerin, 0.05-0.2% sodium hyaluronate, 25-35% GTCC, 2-3% ZnO, 2-3% TiO2, 0.3-0.7% vitamin E, 0.3-0.7% film-forming agent, 0.4-0.6% preservative, and the balance being water.

[0018] This invention provides a method for preparing a phenolic acid-modified attapulgite composite sunscreen, including acid treatment of attapulgite, surfactant modification, loading of phenolic acid biomolecules, and hydrophobic modification. Based on the concept of bio-sunscreen, this invention modifies attapulgite by introducing long-chain alkylammonium salts with surfactants. Then, using the modified attapulgite as a carrier, phenolic acid biomolecules are efficiently and stably loaded through strong electrostatic adsorption to construct a composite synergistic system. Further surface hydrophobic modification yields a composite sunscreen with high stability and excellent sun protection performance.

[0019] The phenolic acid-modified attapulgite composite sunscreen prepared by this invention has high stability, does not degrade under light and heat conditions, does not decrease its ultraviolet absorption capacity, and maintains its structural integrity.

[0020] The phenolic acid-modified attapulgite composite sunscreen prepared in this invention is not prone to agglomeration. This is mainly due to the synergistic effect of the steric hindrance of the one-dimensional rod-shaped fibers of attapulgite, the electrostatic repulsion caused by surfactant modification, and the gentle hydrogen bonding between phenolic acid and the attapulgite carrier. The rod-shaped structure provides physical barrier, the positive surface charge generates electrostatic repulsion, and the gentle loading does not damage the morphology, thus preventing particle agglomeration at its source. Therefore, the sunscreen prepared in this invention has both physical shielding and biological protection functions, with excellent UV absorption capacity, good dispersibility, skin compatibility, and skin feel. It solves the problems of easy agglomeration, whitening, and poor photostability of nanoparticles in existing sunscreen products, significantly improving the product's dispersibility in formulations and its skin-friendly feel during use. It is suitable for the field of cosmetic sunscreens, achieving broad-spectrum UVA / UVB protection, antioxidant properties, and soothing repair, and has broad application prospects.

[0021] In the phenolic acid-modified attapulgite composite sunscreen agent of this invention, phenolic acid molecules are not simply physically adsorbed, but are stably distributed on the surface and within the pores of attapulgite in a highly dispersed, monolayer, or amorphous form. On one hand, attapulgite, as an inorganic mineral barrier, can block direct contact between light, heat, and oxygen and phenolic acid molecules, reducing their photo-oxidation and thermal decomposition. On the other hand, phenolic acid is firmly fixed through hydrogen bonds and electrostatic interactions, restricting molecular movement and making it less prone to spontaneous oxidation, isomerization, or decomposition. Therefore, the attapulgite carrier in the composite sunscreen agent of this invention provides a physical shielding effect, effectively protecting the loaded phenolic acid molecules from photodegradation, allowing them to continuously perform their function of scavenging UV-induced free radicals, achieving a synergistic effect of physical shielding, chemical protection, and antioxidant activity. In this composite sunscreen, attapulgite has excellent natural biocompatibility, is non-toxic to the human body, and is impermeable to the skin. Phenolic acid biomolecules have safe sources and antioxidant activities, ensuring that the composite system can effectively avoid the potential penetration risks of traditional nano-physical sunscreens and the skin irritation problems of chemical sunscreens, ensuring the product's dual safety for the skin and the environment. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the adsorption mechanism of the phenolic acid-modified attapulgite composite sunscreen agent of the present invention; Figure 2 Fourier transform infrared spectra of attapulgite raw material and sunscreen agents in Examples 1-2; Figure 3 The graph shows the DPPH free radical scavenging rate and ABTS free radical scavenging rate of the attapulgite raw material and the sunscreen agents in Examples 1 and 2, where A is the DPPH scavenging rate and B is the ABTS scavenging rate. Figure 4 The diagram shows the vascular reaction phenomena of chicken embryos as positive control, negative control, attapulgite raw material, and sunscreen agents in Examples 1-2; Figure 5 Transmission electron microscope images of the attapulgite raw material and the sunscreen agents in Examples 1-2; Figure 6 The bacterial survival rate of the attapulgite raw material and the sunscreen agents at different concentrations in Examples 1 and 2 is shown in the graph. Figure 7 The ultraviolet absorption spectra of the attapulgite raw material and the sunscreen agents in Examples 1-2 are shown. Figure 8 Zeta potential diagrams of attapulgite raw material, acidified attapulgite, modified attapulgite, and p-coumaric acid-modified attapulgite sunscreen agent in Example 2. Figure 9 The graph shows the SPF increase of the sunscreen lotions in Examples 1 and 2. Figure 10The graph shows the changes in the ultraviolet absorption spectrum of the sunscreen agent in Example 1 under different temperatures and light exposure times. Detailed Implementation

[0023] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0024] This invention provides a method for preparing a phenolic acid-modified attapulgite composite sunscreen, comprising the following steps: Attapulgite is mixed with an acid solution and subjected to acid treatment to obtain acidified attapulgite. The acidified attapulgite, water, and surfactant are mixed to perform the first modification, resulting in modified attapulgite. The modified attapulgite was mixed with phenolic acid biomolecules and a solvent, and the pH was adjusted to the desired level to obtain an attapulgite-loaded phenolic acid complex. The surface hydrophobic modifier was mixed with an alcohol solution and hydrolyzed to obtain the hydrolysis product. The attapulgite-loaded phenolic acid complex was mixed with the hydrolysis product and subjected to a second modification to obtain a phenolic acid-modified attapulgite composite sunscreen.

[0025] This invention involves mixing attapulgite with an acid solution and subjecting it to acid treatment to obtain acidified attapulgite.

[0026] In this invention, the acid solution preferably includes one or more of hydrochloric acid, sulfuric acid, acetic acid, carbonic acid, and dilute nitric acid; when the acid solution is two or more of the above, this invention does not have a special limitation on the ratio of different types of acid solutions, and can be adjusted according to needs.

[0027] In this invention, the concentration of the acid solution is preferably 0.3~1.7 mol / L, more preferably 0.5~1.5 mol / L, and even more preferably 1 mol / L. This invention does not have a special limitation on the ratio of attapulgite to acid solution, as long as the attapulgite is completely immersed in the acid solution. In the embodiments, the ratio of attapulgite to acid solution is specifically 15 g: 300 mL.

[0028] The present invention preferably involves immersing attapulgite in an acid solution and performing acid treatment by continuous stirring under high temperature conditions.

[0029] In this invention, the acid treatment temperature is preferably 80~150 ℃, more preferably 80~120 ℃, and even more preferably 85 ℃, and the time is preferably 5~48 h, more preferably 8~10 h.

[0030] After the acid treatment is completed, the present invention preferably filters the obtained suspension, separates it using a high-speed centrifuge, washes it with deionized water until neutral, dries it at 100 ℃, grinds and pulverizes it, and passes it through a 100~500 mesh standard sieve to obtain acidified attapulgite; the centrifugation speed of the high-speed centrifuge is preferably 5000~10000 rpm, more preferably 7000~8000 rpm, and the centrifugation time is preferably 3~10 min, more preferably 5~8 min.

[0031] After obtaining acidified attapulgite, the present invention mixes the acidified attapulgite, water and surfactant to carry out the first modification to obtain modified attapulgite.

[0032] In this invention, the surfactant preferably includes one or more of cocamidopropyl betaine, lauryl betaine, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, and sulfobetaine; when the surfactant is two or more of the above, this invention does not have a special limitation on the ratio of different types of surfactants, and any ratio is acceptable.

[0033] In this invention, the mass ratio of the surfactant to acidified attapulgite is preferably 0.1:1 to 5:1, more preferably 0.15:1 to 2:1, and even more preferably 0.175:1 to 0.35:1.

[0034] In this invention, acidified attapulgite is preferably ultrasonically dispersed in water to obtain a suspension, a surfactant is added, and the suspension is subjected to a first modification under mechanical stirring. This invention does not have a specific limitation on the amount of water used, as long as the material is evenly dispersed.

[0035] In this invention, the ultrasonic dispersion temperature is 20~40 ℃, more preferably 25 ℃, the time is 10~30 min, more preferably 10~15 min, and the ultrasonic power is 50~150 W, more preferably 100 W.

[0036] In this invention, the preferred temperature for the first modification is 30-100 °C, more preferably 50-60 °C, and the preferred time is 10-30 h, more preferably 16-24 h. During the first modification process, quaternary ammonium cations undergo electrostatic adsorption and cation exchange with the negative potential points on the attapulgite surface. The positive charge centers of the quaternary ammonium salt and the negative charge on the mineral surface form a strong electrostatic interaction, causing the surfactant to be firmly assembled on the attapulgite surface.

[0037] After the first modification is completed, the present invention preferably separates the obtained product using a high-speed centrifuge (centrifugation speed of 5000~10000 rpm, more preferably 7000 rpm, centrifugation time of 3~10 min, more preferably 3~5 min), the separated precipitate is repeatedly washed with distilled water until impurity ions are removed, dried at 45 ℃, ground and pulverized, and passed through a 100~500 mesh standard sieve to obtain modified attapulgite.

[0038] After obtaining the modified attapulgite, the present invention mixes the modified attapulgite with phenolic acid biomolecules and solvent, adjusts the pH to the required level, and performs compounding to obtain an attapulgite-loaded phenolic acid complex.

[0039] In this invention, the phenolic acid biomolecules preferably include one or more of caffeic acid, gallic acid, ferulic acid, p-coumaric acid, ellagic acid, and p-hydroxybenzoic acid; when the phenolic acid biomolecules are two or more of the above, this invention does not have a special limitation on the ratio of different types of phenolic acid biomolecules, and any ratio is acceptable.

[0040] In this invention, the mass ratio of the modified attapulgite to phenolic acid biomolecules is preferably 0.5:1 to 5:1, more preferably 1:1 to 3:1, and even more preferably 1:1.

[0041] In this invention, the solvent is preferably pure water or an ethanol solution; the volume concentration of the ethanol solution is preferably 10-50%; this invention does not have a special limitation on the amount of solvent used, as long as the material is evenly dispersed.

[0042] In this invention, modified attapulgite and phenolic acid biomolecules are preferably added to a solvent, adjusted to the desired pH, and compounded under stirring conditions.

[0043] The present invention preferably uses 1 mol / L hydrochloric acid to adjust the pH to 2-5, more preferably 2-3; the composite temperature is preferably 10-50 ℃, more preferably 25 ℃, the time is preferably 60-180 min, more preferably 100-120 min, and the stirring speed is preferably 200-700 rpm, more preferably 500-600 rpm.

[0044] After the composite is completed, the present invention preferably separates the obtained product using a high-speed centrifuge (centrifugation speed of 5000~10000 rpm, more preferably 7000 rpm, centrifugation time of 3~10 min, more preferably 3~5 min), then washes it three times with distilled water, dries it at 45 ℃, grinds and pulverizes it, and passes it through a 100~500 mesh standard sieve to obtain the attapulgite-supported phenolic acid complex.

[0045] This invention involves mixing a surface hydrophobic modifier with an alcohol solution and then hydrolyzing the mixture to obtain the hydrolysis product.

[0046] In this invention, the surface hydrophobic modifier preferably includes one or more of the following: dodecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, vinyltriethoxysilane, and dodecyltriethoxysilane. When the surface hydrophobic modifier is two or more of the above, this invention does not have a special limitation on the ratio of different types of surface hydrophobic modifiers, and any ratio is acceptable.

[0047] In this invention, the alcohol solution preferably comprises an ethanol solution, and the concentration of the alcohol solution is preferably 50-90 wt.%, more preferably 60-80 wt.%.

[0048] In this invention, the preferred ratio of the surface hydrophobic modifier to the alcohol solution is 20 μL:200 mL to 80 μL:100 mL, and more preferably 50 μL:100 mL.

[0049] In this invention, the hydrolysis temperature is preferably 10~50 ℃, more preferably 25 ℃, and the hydrolysis time is preferably 1~10 h, more preferably 2~5 h, and even more preferably 2 h. This invention hydrolyzes the surface hydrophobic modifier before modification, which facilitates the conversion of hydrophilicity to hydrophobicity, prevents aggregation, and allows the composite sunscreen agent to be more evenly dispersed in the sunscreen emulsion, resulting in a more refreshing feel on the skin. Ultimately, this achieves a stable, surfactant-free sunscreen Pickering emulsion system.

[0050] The present invention mixes the attapulgite-loaded phenolic acid complex with the hydrolysis product and performs a second modification to obtain a phenolic acid-modified attapulgite composite sunscreen.

[0051] In this invention, the preferred ratio of the surface hydrophobic modifier to the attapulgite-supported phenolic acid composite is (10~100) μL:(2~5) g, more preferably (20~60) μL:(2~3) g, and even more preferably 50 μL:2 g.

[0052] In this invention, the temperature for the second modification is preferably 10~100 ℃, more preferably 25 ℃, and the time is preferably 2~12 h, more preferably 4~8 h. During the second modification process, the silanol groups after hydrolysis of the surface hydrophobic modifier undergo dehydration condensation with the silanol groups and aluminol groups on the surface of attapulgite to form stable Si-O-Si covalent bonds.

[0053] After completing the second modification, the present invention preferably dries the obtained product at 45 °C and passes it through a 100-500 mesh standard sieve to obtain a phenolic acid-modified attapulgite composite sunscreen.

[0054] This invention provides a phenolic acid-modified attapulgite composite sunscreen prepared by the preparation method described in the above technical solution.

[0055] The phenolic acid-modified attapulgite composite sunscreen of the present invention consists of modified attapulgite, phenolic acid biomolecules loaded on the surface of modified attapulgite, and a hydrophobic modification layer on the surface; the phenolic acid biomolecules are bound to the modified attapulgite by electrostatic adsorption.

[0056] like Figure 1 As shown, acid-treated attapulgite removes impurities from its pores through an acid solution, exposing more silanol and aluminol hydroxyl groups and enhancing its negative charge. Surfactants are adsorbed onto its surface via electrostatics and hydrogen bonding, achieving charge reversal to form an electropositive carrier. Phenolic acid molecules are loaded onto the surface of this carrier through electrostatic attraction and hydrogen bonding to form a complex. Then, the silanol groups generated by hydrolysis of silane condense with the surface groups of the complex, causing the long-chain alkyl hydrophobic groups to be oriented to form a hydrophobic modified layer on the outermost layer, thus constructing a phenolic acid-attapulgite composite sunscreen.

[0057] This invention provides the application of the phenolic acid-modified attapulgite composite sunscreen agent described above in the field of cosmetics, wherein the cosmetics include sunscreen lotion, sunscreen cream, sunscreen gel or sunscreen spray.

[0058] This invention provides a Pickering sunscreen lotion comprising the phenolic acid-modified attapulgite composite sunscreen agent described in the above technical solution, an aqueous phase, an oil phase, and a preservative.

[0059] In this invention, the aqueous phase preferably includes a composite sunscreen agent, glycerin, sodium hyaluronate and water; the oil phase preferably includes GTCC, ZnO, TiO2, vitamin E and a film-forming agent.

[0060] In this invention, the film-forming agent is preferably a PPG-12 / SMDI copolymer, and the preservative is preferably phenoxyethanol.

[0061] In this invention, the Pickering sunscreen lotion, by total mass percentage (100%), comprises the following components: 8-12% compound sunscreen agent, 3-6% glycerin, 0.05-0.2% sodium hyaluronate, 25-35% GTCC (caprylic / capric triglyceride), 2-3% ZnO, 2-3% TiO2, 0.3-0.7% vitamin E, 0.3-0.7% film-forming agent, 0.4-0.6% preservative, and the balance being water.

[0062] In this invention, the Pickering sunscreen lotion contains, more preferably, 10% of a compound sunscreen agent, 5% of glycerin, 0.1% of sodium hyaluronate, 30% of GTCC, 2.5% of ZnO, 2.5% of TiO2, 0.5% of vitamin E, 0.5% of a film-forming agent, and 0.5% of a preservative.

[0063] In this invention, the preferred method for preparing the Pickering sunscreen lotion is as follows: The raw materials corresponding to the water phase were stirred and dispersed evenly at room temperature to obtain the aqueous phase. The raw materials corresponding to the oil phase were mixed and heated and stirred at 60 °C on a heating plate until evenly dispersed to obtain the oil phase. The oil phase was added to the aqueous phase, and after the oil phase was evenly dispersed in the system, it was placed in a homogenizer at 15000 rpm for 2 min. The preservative was added and stirred evenly to obtain the Pickering sunscreen emulsion based on ferulic acid-modified attapulgite.

[0064] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0065] Unless otherwise specified, the experimental methods described in the various embodiments of this invention are conventional methods; unless otherwise specified, the raw materials used are all commercially available products, and the proportions are all by mass percentage.

[0066] Example 1

[0067] (1) Weigh 15 g of attapulgite, add 300 mL of 1 mol / L hydrochloric acid, stir continuously for 8 h at 85 ℃, filter the suspension, separate it for 3 min at 7000 rpm using a high-speed centrifuge, wash it with deionized water until neutral, dry it at 100 ℃, grind it into powder, and pass it through a 100-mesh standard sieve to obtain acidified attapulgite. (2) Take 4 g of acidified attapulgite and ultrasonically disperse it in 200 mL of pure water. The ultrasonic dispersion temperature is 25 ℃, the time is 10 min, and the ultrasonic power is 100 W to obtain a suspension. Add 0.7 g of octadecyltrimethylammonium chloride to the suspension and mechanically stir at 50 ℃ for 24 h. Separate the product with a high-speed centrifuge at 7000 rpm for 3 min. Wash the separated precipitate repeatedly with distilled water, dry it at 45 ℃, grind it into powder, and pass it through a 100-mesh standard sieve to obtain modified attapulgite. (3) Add 1 g of modified attapulgite and 1 g of ferulic acid to 100 mL of pure water, adjust the pH to 2 with 1 mol / L hydrochloric acid, stir at 25 ℃ and 500 rpm for 120 min, separate with a high-speed centrifuge at 7000 rpm for 3 min, dry at 45 ℃, grind and pulverize, and pass through a 100-mesh standard sieve to obtain the attapulgite-supported ferulic acid complex. (4) 50 μL of dodecyltriethoxysilane was added dropwise to 100 mL of ethanol solution (the concentration of the ethanol solution was 60 wt.%) and hydrolyzed at 25 °C for 2 h. Then, 2 g of attapulgite-loaded ferulic acid complex was added to the hydrolysis product and reacted at 25 °C for 4 h. The product was dried at 45 °C and passed through a 300-mesh standard sieve to obtain ferulic acid-modified attapulgite composite sunscreen.

[0068] Example 2

[0069] (1) Weigh 15 g of attapulgite, add 300 mL of 1 mol / L hydrochloric acid, stir continuously for 8 h at 85 ℃, filter the suspension, separate it for 3 min at 7000 rpm using a high-speed centrifuge, wash it with deionized water until neutral, dry it at 100 ℃, grind it into powder, and pass it through a 100-mesh standard sieve to obtain acidified attapulgite. (2) Take 4 g of acidified attapulgite and ultrasonically disperse it in 200 mL of pure water. The ultrasonic dispersion temperature is 25 ℃, the time is 10 min, and the ultrasonic power is 100 W to obtain a suspension. Add 1.4 g of octadecyltrimethylammonium chloride to the suspension and mechanically stir at 50 ℃ for 24 h. Separate the product with a high-speed centrifuge at 7000 rpm for 3 min. Wash the separated precipitate repeatedly with distilled water, dry it at 45 ℃, grind it into powder, and pass it through a 100-mesh standard sieve to obtain modified attapulgite. (3) Add 1 g of modified attapulgite and 1 g of p-coumaric acid to 100 mL of pure water, adjust the pH to 5 with 1 mol / L hydrochloric acid, stir at 25 ℃ and 500 rpm for 120 min, separate with a high-speed centrifuge at 7000 rpm for 3 min, dry at 45 ℃, grind and pulverize, and pass through a 100-mesh standard sieve to obtain the attapulgite-supported p-coumaric acid complex. (4) 50 μL of dodecyltriethoxysilane was added dropwise to 100 mL of ethanol solution (the concentration of the ethanol solution was 60 wt.%) and hydrolyzed at 25 °C for 2 h. Then, 2 g of attapulgite-loaded p-coumaric acid complex was added to the hydrolysis product and reacted at 25 °C for 4 h. The product was dried at 45 °C and passed through a 300-mesh standard sieve to obtain p-coumaric acid-modified attapulgite composite sunscreen.

[0070] Application examples

[0071] Table 1 Pickering Sunscreen Lotion Formula

[0072] Application Example 1

[0073] Using Table 1 as the standard, the ferulic acid-modified attapulgite composite sunscreen agent in Example 1 was used. The A phase raw material was stirred in a mixer at room temperature to ensure uniform dispersion. The B phase raw material was mixed and heated and stirred at 60 °C on a heating plate until uniformly dispersed. The B phase was added to the A phase. After the oil phase was uniformly dispersed in the system, it was placed in a homogenizer at 15000 rpm for 2 min. The C phase preservative was added and stirred evenly to obtain the Pickering sunscreen emulsion based on ferulic acid-modified attapulgite.

[0074] Application Example 2

[0075] Using Table 1 as the standard, the p-coumaric acid-modified attapulgite composite sunscreen agent in Example 2 was used. The A phase raw material was stirred in a mixer at room temperature to ensure uniform dispersion. The B phase raw material was mixed and heated and stirred at 60 °C on a heating plate until uniformly dispersed. The B phase was added to the A phase. After the oil phase was uniformly dispersed in the system, it was placed in a homogenizer at 15000 rpm for 2 min. The C phase preservative was added and stirred evenly to obtain a Pickering sunscreen emulsion based on p-coumaric acid-modified attapulgite.

[0076] Test Results

[0077] 1) Figure 2 Fourier transform infrared spectra of attapulgite raw material and sunscreen agents in Examples 1-2; Figure 2 It can be seen that phenolic acid was successfully loaded, and the surface modification was completed.

[0078] 2) DPPH radical scavenging experiment and ABTS radical scavenging experiment

[0079] DPPH free radical scavenging experiment: The scavenging ability of the composite samples (Examples 1 and 2) on DPPH free radicals was determined. 20 mg of DPPH was dissolved in 250 mL of ethanol to prepare a 0.2 mmol / L DPPH solution. The composite samples were dissolved in ethanol-water mixtures to prepare sample solutions of different concentrations (10, 50, and 100 μg). 1 mL of the sample solution was mixed with 2 mL of the DPPH solution, and the mixture was reacted in the dark for 30 min. The absorbance was then measured at 517 nm. The scavenging rate was calculated using the following formula: The formula for calculating the DPPH free radical scavenging rate is:

[0080] in, A b represents the absorbance of the DPPH solution. As represents the absorbance of the test liquid.

[0081] ABTS free radical scavenging experiment: The antioxidant activity of the composite samples (Examples 1 and 2) was analyzed using the free radical cation ABTS+ (2,2'-azo-bis(3-ethylbenzothiazoline-6-sulfonic acid)). First, 5 mL of 7 mM fresh ABTS ethanol solution was mixed with an equal volume of 2.45 mM potassium persulfate (K2S2O8) and incubated in the dark for 12 hours. The solution was then adjusted with ethanol until the absorbance at 734 nm was 0.70 ± 0.05 (ABTS solution). The experiment was performed in 96-well plates, with 20 µL of each sample solution and 180 µL of the ABTS+ free radical solution. Distilled water was used as a blank control instead of the sample solution, and absorbance was measured using the same method. After incubation in the dark for 10 min, the absorbance of the supernatant was measured at 734 nm using an enzyme-linked immunosorbent assay (ELISA) labeler. The ABTS+ free radical scavenging capacity was calculated using the following formula: The formula for calculating the ABTS+ free radical scavenging rate is as follows:

[0082] Among them, among them, A b represents the absorbance of the control group solution. A s represents the absorbance of the sample group.

[0083] Figure 3 The graph shows the DPPH and ABTS free radical scavenging rates of the attapulgite raw material and the sunscreen agents in Examples 1 and 2, where A represents the DPPH scavenging rate and B represents the ABTS scavenging rate. Figure 3 It can be seen that the DPPH / ABTS sunscreen agents in Examples 1 and 2 have a significantly higher removal rate than pure attapulgite.

[0084] 3) The eye irritation of the samples was assessed using the standard procedure of the Heteroallantoic Membrane Test (HET-CAM) from the European Centre for Validation of Alternative Methods (ECVAM). The negative and positive controls were 0.9% NaCl solution and 0.1 mol / L NaOH solution, respectively. The outer surface of fertilized eggs was wiped with 75% alcohol, with the air cell facing upwards, and incubated for 9 days in a constant temperature incubator at 37±1℃ and 65±2% relative humidity. On day 10, the location of the air cell was determined using an egg candler, and a small hole was cut at the top of the air cell using an egg opener. The shell above the air cell was peeled off with tweezers, and physiological saline solution was dripped in to moisten the air cell membrane. After absorbing excess liquid, the air cell membrane structure was carefully peeled off, and images were collected and recorded under a microscope.

[0085] All test samples, including attapulgite (PAL) and compound sunscreens (Examples 1 and 2), were prepared into 10 mg / mL suspensions on the day of testing. 300 μL of each test sample was dropped onto exposed blood vessels and left for 3 minutes. The samples were then quickly washed away with physiological saline. Changes in the blood vessels were observed under a microscope, and images were recorded and scored. The scoring criteria in this study used an endpoint evaluation method, with vascular responses categorized as hemorrhage, coagulation, and angiogenesis. Six parallel tests were performed for each sample. The scores for the three vascular responses were summed, and the highest score among the three indicators was taken as the final S-value for that sample. The stimulation grading table is shown in Table 2.

[0086] Table 2 HET-CAM Stimulation Response Scoring Table

[0087] Figure 4 The diagram shows the vascular reaction phenomena of chicken embryos with positive control, negative control, attapulgite raw material, and sunscreen agents in Examples 1-2. Specific data are shown in Table 3.

[0088] Table 3. Irritation evaluation of positive control, negative control, attapulgite raw material, and sunscreen agents in Examples 1-2.

[0089] Depend on Figure 4 As shown in Table 3, the S value of the sunscreen agent in Examples 1-2 in the chicken embryo experiment is ≤1, indicating that it is non-irritating.

[0090] 4) Figure 5 Transmission electron microscope images of attapulgite raw material and the sunscreen agents in Examples 1-2; Figure 5 It can be seen that the original attapulgite exhibits a clear rod-shaped fibrous structure; after acid modification, surfactant modification and phenolic acid loading, the sunscreens in Examples 1 and 2 still maintain a complete fibrous morphology, with no obvious particle agglomeration, and are evenly dispersed. The modification and phenolic acid loading process did not damage the attapulgite structure, and the composite sunscreen has good dispersion stability.

[0091] 5) The antibacterial activity of PAL and two composite samples (FA@0.5STAC / PAL, PCA@1CTAB / PAL) against Staphylococcus aureus and Escherichia coli was determined using the plate count method. Staphylococcus aureus was cultured in tryptone soy broth, and Escherichia coli was cultured in nutrient broth. Fresh strains cultured overnight at 37 °C were used to quantify 1×10⁻⁶ samples. 8 A bacterial suspension of CFU / mL was diluted with sterile culture medium to a concentration of 1×10⁻⁶.6 The working bacterial suspension was prepared using CFU / mL. Samples were prepared with sterile water to concentrations of 100, 50, and 10 mg / L. The sample solutions of different concentrations were mixed 1:1 with the working bacterial suspension and incubated at 37 ℃ and 150 rpm for 24 ± 1 h with shaking. 100 μL of the mixed culture was diluted and spread onto agar plates. The plates were incubated at 37 ℃ until colonies were clearly visible, and then counted. Plates with 30-300 effective colonies were counted, and the survival rates of the two bacteria were calculated.

[0092] The formula for calculating the survival rate is:

[0093] in, C 1 indicates the number of colonies on the sample plate. C 0 represents the number of colonies on the negative control plate.

[0094] Figure 6 The graph shows the bacterial survival rate of the attapulgite raw material and the sunscreen agents at different concentrations in Examples 1 and 2; from Figure 6 It can be seen that as the concentration of the phenolic acid-modified attapulgite composite sunscreen increases, the inhibition rate of the composite sunscreens in Examples 1 and 2 against Escherichia coli and Staphylococcus aureus gradually increases, and this trend is dose-dependent.

[0095] 6) Record the ultraviolet absorption spectrum of the sample using an ultraviolet spectrophotometer, with barium sulfate as a blank control, and record the ultraviolet absorption spectrum at 200-500 nm.

[0096] Figure 7 The UV absorption spectra of the attapulgite raw material and the sunscreen agents in Examples 1-2 are shown; Figure 7 It can be seen that the absorption of UVA / UVB across the entire spectrum is enhanced, indicating that the composite sample exhibits broad-spectrum ultraviolet protection capability.

[0097] 7) Figure 8 The Zeta potential diagrams for the attapulgite raw material, acidified attapulgite, modified attapulgite, and p-coumaric acid-modified attapulgite sunscreen agent in Example 2 are shown below. Figure 8 It can be seen that natural attapulgite is negatively charged; the negative charge is enhanced after acid modification; the charge changes from negative to positive after modification with cationic surfactant, proving that the modification was successful; the positive potential decreases after loading with phenolic acid, and the surface charge shows a downward trend, indicating that the phenolic acid loading is complete.

[0098] 8) The sun protection efficacy of the product was evaluated using an in vitro instrumental method. An SPF 290AS analyzer was used, covering the full UVB and UVA spectrum. The sample was uniformly coated onto a polymethyl methacrylate (PMMA) plate. Nine randomly selected points on the plate were irradiated with ultraviolet light of different wavelengths. The absorbance of the sample was measured to calculate its in vitro SPF value, thus objectively evaluating the sun protection efficacy of the sample. Before the test, the PMMA plate (50×50 mm) and the test sample were placed in a dark environment at 27 (±2)℃ for at least 12 hours. A blank PMMA plate was used for instrument calibration. The test sample was uniformly coated onto the PMMA plate at a concentration of 1.3 mg / cm³. 2 (±1.6%). After application, place the sample in a dark environment for at least 30 minutes. Measure the in vitro SPF value of each sample using a sun protection factor analyzer (SPF 290AS).

[0099] Figure 9 This is a graph showing the SPF increase of the sunscreen lotions used in Examples 1-2; from Figure 9 It can be seen that the emulsion has a significantly improved SPF, indicating high protective efficiency.

[0100] 9) Thermal stability and light stability tests: Thermal stability tests were conducted by aliquoting 0.05 g of the sunscreen sample from Example 1 into a quartz sample cell and heating it at 60 °C, 90 °C, and 120 °C for 6 h, respectively. The thermal degradation behavior of the samples was analyzed using ultraviolet-visible absorption spectroscopy (UV-vis) to assess the temperature stability of the samples.

[0101] A solar stability test was conducted. 0.05 g of the sunscreen sample from Example 1 was dispensed into a quartz sample cell and irradiated for 2 h, 3 h, and 4 h under a solar simulator (SOL 500 RF2) (UVA intensity 1.7 mW / cm²). 2 The UVB intensity was 0.17 mW / cm². 2 The photodegradation behavior of the samples was analyzed using ultraviolet-visible absorption spectroscopy (UV-vis) to assess the stability of the samples to sunlight.

[0102] Figure 10 The graph shows the changes in the ultraviolet absorption spectrum of the sunscreen agent in Example 1 under different temperatures and light exposure times; from Figure 10 It can be seen that the UV absorption curve of this composite sunscreen agent did not change significantly under heating at 60~120℃ and long-term UV irradiation (2~4h), indicating that the phenolic acid molecules are firmly bound to attapulgite and are not easily decomposed and detached, thus maintaining the stable sunscreen function.

[0103] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a phenolic acid-modified attapulgite composite sunscreen, characterized in that, Includes the following steps: Attapulgite is mixed with an acid solution and subjected to acid treatment to obtain acidified attapulgite. The acidified attapulgite, water, and surfactant are mixed to perform the first modification, resulting in modified attapulgite. The modified attapulgite was mixed with phenolic acid biomolecules and a solvent, and the pH was adjusted to the desired level to obtain an attapulgite-loaded phenolic acid complex. The surface hydrophobic modifier was mixed with an alcohol solution and hydrolyzed to obtain the hydrolysis product. The attapulgite-loaded phenolic acid complex was mixed with the hydrolysis product and subjected to a second modification to obtain a phenolic acid-modified attapulgite composite sunscreen.

2. The preparation method according to claim 1, characterized in that, The acid solution includes one or more of hydrochloric acid, sulfuric acid, acetic acid, carbonic acid, and dilute nitric acid; the concentration of the acid solution is 0.3~1.7 mol / L; the acid treatment temperature is 80~150 ℃, and the time is 5~48 h.

3. The preparation method according to claim 1, characterized in that, The surfactant includes one or more of cocamidopropyl betaine, lauryl betaine, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, and sulfobetaine; The mass ratio of the surfactant to acidified attapulgite is 0.1:1 to 5:1; the first modification temperature is 30 to 100 °C, and the time is 10 to 30 h.

4. The preparation method according to claim 1, characterized in that, The phenolic acid biomolecules include one or more of caffeic acid, gallic acid, ferulic acid, p-coumaric acid, ellagic acid, and p-hydroxybenzoic acid; the mass ratio of the modified attapulgite to the phenolic acid biomolecules is 0.5:1 to 5:

1. Adjust the pH to 2-5, the temperature of the compounding process is 10-50 ℃, the time is 60-180 min, and the stirring speed is 200-700 rpm.

5. The preparation method according to claim 1, characterized in that, The surface hydrophobic modifier includes one or more of dodecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, vinyltriethoxysilane, and dodecyltriethoxysilane; The alcohol solution includes an ethanol solution with a concentration of 50-90 wt.%; the hydrolysis temperature is 10-50°C and the time is 1-10 h.

6. The preparation method according to claim 1, characterized in that, The ratio of the surface hydrophobic modifier to the attapulgite-supported phenolic acid composite is (10~100) μL:(2~5) g; the second modification temperature is 10~100 ℃ and the time is 2~12 h.

7. The phenolic acid-modified attapulgite composite sunscreen prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the phenolic acid-modified attapulgite composite sunscreen agent according to claim 7 in the cosmetics field, characterized in that, The cosmetics include sunscreen lotion, sunscreen cream, sunscreen gel, or sunscreen spray.

9. A Pickering sunscreen lotion, characterized in that, It includes the phenolic acid-modified attapulgite composite sunscreen as described in claim 7, an aqueous phase, an oil phase, and a preservative.

10. The Pickering sunscreen lotion according to claim 9, characterized in that, Based on a total mass percentage of 100%, the Pickering sunscreen lotion comprises the following components: 8-12% complex sunscreen agent, 3-6% glycerin, 0.05-0.2% sodium hyaluronate, 25-35% GTCC, 2-3% ZnO, 2-3% TiO2, 0.3-0.7% vitamin E, 0.3-0.7% film-forming agent, 0.4-0.6% preservative, and the balance being water.

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