Surface-treated inorganic particles, their manufacturing method, dispersion thereof, and cosmetic composition containing the same

Abstract

To provide surface-treated inorganic particles containing catechins, which can suppress discoloration for a long period of time without loss of antioxidant capacity of catechins, and a manufacturing method thereof.SOLUTION: Surface-treated inorganic particles, comprising inorganic particles and metal-organic structures bonded to the surface of the inorganic particles, wherein polyphenols form the skeleton of the metal-organic structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This description relates to surface-treated inorganic particles, methods for their preparation, dispersions thereof, and cosmetic compositions containing said inorganic particles or dispersions. [Background technology]

[0002] Inorganic particles, especially nano-inorganic particles, have new properties that have not been observed in existing inorganic particles measuring tens to hundreds of microns, and often exhibit improved properties. As such, they are being developed in a variety of fields, including semiconductors, displays, machinery, automobiles, and daily necessities.

[0003] The representative properties of such nano-inorganic particles can be classified into optical, physicochemical, and magnetic properties, but in particular, extremely small nano-inorganic particles such as quantum dots have the property that the smaller the particle diameter, the greater the difference in the electron energy levels of the surface atoms.When a material absorbs light and exhibits color, it occurs from the movement of electrons between energy levels, and the difference in energy levels causes a change in the wavelength band and hue of the light absorbed, so quantum dots have the property of changing hue depending on their size. Taking advantage of this, they are applied in the medical and electronics industries, such as displays with high color reproduction, analysis, and diagnosis.

[0004] Furthermore, nano-sized inorganic particles have a large surface area per unit volume, resulting in a higher number of surface atoms relative to the total number of atoms. In other words, nano-inorganic particles exist in an unstable state with increased surface energy. These unstable particles can easily overcome the energy barrier required for a reaction even with a small amount of energy, making them highly reactive and useful as catalysts in a variety of reactions. For example, titanium dioxide particles with a particle size of 20 nm or less have sterilizing, cleaning, and anti-fogging properties even when exposed to only weak ultraviolet light emitted from fluorescent lamps. Furthermore, nano-inorganic particles have enhanced magnetic properties due to the increased strength of the magnetic field formed around the atoms, making them suitable for use in medical applications such as magnetic resonance imaging (MRI).

[0005] Despite the great potential and growth potential of nano-inorganic particle materials, their industrial application remains limited. Typical reasons for this include chemical instability and cohesion due to the high surface energy of nano-inorganic particle powders, expensive manufacturing processes, and a lack of research to assess their safety for human health and the environment. The most commonly identified problems are low dispersion stability, which makes nano-inorganic particles prone to spontaneous combustion and oxidation due to their high surface energy. Because particles aggregate to reduce their surface energy, dispersion in a solvent can result in gelling, a rapid increase in viscosity above a certain concentration. Even after temporary dispersion with high energy, rapid re-agglomeration and phase separation occur, resulting in uneven coating and preventing the nanoparticles from fully utilizing their intended functionality.

[0006] For example, titanium dioxide (TiO2) powder, an inorganic metal oxide, is a white pigment widely used in various paints. Its ability to absorb and reflect ultraviolet rays makes it a useful raw material for UV protection in cosmetics, and it is also used as a semiconductor and food additive. However, it suffers from the same problems as typical oxide nanoparticles, such as difficulty in high-concentration dispersion in various solvents and rapid aggregation and phase separation. Furthermore, reactive oxygen species (ROS) radicals generated by the strong photocatalytic activity of titanium dioxide can cause discoloration and oxidation of other ingredients in cosmetics, pharmaceuticals, and food formulations, and have been shown to attack cell membranes and nuclei in living organisms, resulting in DNA damage and the development of cancer, dementia, and aging.

[0007] A common method for solving this problem is to use a dispersion stabilizer such as a surfactant together with inorganic metal oxides (inorganic particles).

[0008] However, even if a dispersion stabilizer is added, the dispersion stability of the inorganic particles is not improved to a satisfactory level, and the dispersion stabilizer reduces or eliminates the antioxidant ability (radical scavenging rate) of the inorganic particles. Furthermore, when the inorganic particles are used together with other ingredients that are easily discolored, the discoloration of the other ingredients significantly reduces the sensory and efficacy of the final product, which cannot be solved.

[0009] Polyphenols, including tannins found abundantly in plant stems and fruit skins, catechins found in large amounts in green tea, resveratrol in grapes, and quercetin found in large amounts in apples and onions, are beneficial substances that delay aging caused by cell damage in the human body due to their strong antioxidant properties. However, while polyphenols have excellent convergent, skin-protecting, protective, antimutagenic, hemostatic, detoxifying, antioxidant, and sebum secretion-inhibiting properties, they are highly unstable and susceptible to discoloration due to heat and oxygen. Discoloration of green tea and apple juice can be observed if left unattended, and this is due to polyphenols.

[0010] Therefore, although attempts have been made to apply polyphenols, particularly catechins, to cosmetic compositions to realize the excellent efficacy of catechins in cosmetics, the problem of the composition easily discoloring when applied to cosmetic compositions has not yet been resolved, and efforts to develop cosmetic compositions using catechins are still ongoing.

[0011] There are eight main components of tea catechins found in nature, with 10% to 15% of the total dry weight of green tea leaves being tea catechins, of which epigallocatechin gallate (EGCG) accounts for 50% to 60%. Gallocatechin gallate (GCG) is the second carbon isomer of epigallocatechin gallate and is a low-abundance catechin that accounts for only 0.8% to 1.5% of the total catechin content in green tea.

[0012] The representative catechins present in green tea are epicatechin [(-)EC], epigallocatechin [(-)EGC], epicatechin gallate [(-)ECG], and epigallocatechin gallate [(-)EGCG]. The reported antioxidant effects of green tea, including cholesterol absorption reduction, triglyceride suppression, antiviral, antitumor, anticancer, skin beauty, obesity suppression, and mutagenicity suppression, are typified by the activities of these catechins. Recently, it has been confirmed that these catechins are converted to their isomeric non-epicatechins, namely, catechin [(-)C], gallocatechin [(-)GC], catechin gallate [(-)CG], and gallocatechin gallate [(-)GCG], respectively, during the pasteurization process used to make green tea beverages. It has also been confirmed that when green tea leaves are soaked in hot water, the epicatechins in green tea leaves are converted to non-epicatechins, i.e., catechin epimers. The antioxidant effects of these isomers are comparable to those of the individual isomers (Non-Patent Document 1; Non-Patent Document 2), and catechin gallate and gallocatechin gallate are superior to their isomers in reducing cholesterol absorption (Non-Patent Document 3). The anti-allergy effects of its isomer, gallocatechin gallate, are also superior to those of epigallocatechin gallate (Non-Patent Document 4). Gallocatechin gallate activates peroxisome proliferator-activated receptor subtype alpha (PPAR-alpha) and promotes the expression of the skin moisturizing factor filaggrin, thereby providing excellent skin dryness prevention and moisturizing effects (Patent Document 1). In addition, non-epi-catechins present in drinking green tea not only stabilize epi-catechins but also have a superior taste. Thus, the industrial utility of non-epi-catechins such as gallocatechin gallate has become clear, and efforts are being made to utilize this. However, their content in green tea is very low, and the conversion of catechins to epimers requires high temperatures and pH adjustments, making it impossible to extract, separate, purify, and mass-produce non-epi-catechins such as gallocatechin gallate from green tea leaves. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Korean Patent No. 10-0659138 [Non-patent literature]

[0014] [Non-Patent Document 1] Xu JZ et al., British Journal of Nutrition, 91, 873-881, 2004 [Non-patent document 2] Unno T et al., J. Sci. Food Agri., 80, 601-606, 2000 [Non-patent document 3] Ikeda I et al., J. Agric. Food Chem., 51, 7303-7307, 2003 [Non-patent document 4] Nagai H et al., J. Sci. Food Agri., 85, 1606-1612, 2005 Summary of the Invention [Problem to be solved by the invention]

[0015] One embodiment provides surface-treated inorganic particles containing catechins that can inhibit discoloration for a long period of time without losing the antioxidant ability of the catechins.

[0016] Another embodiment provides a method for producing the surface-treated inorganic particles.

[0017] Yet another embodiment provides a dispersion in which the surface-treated inorganic particles are dispersed.

[0018] Yet another embodiment provides a cosmetic composition comprising the surface-treated inorganic particles or the dispersion. [Means for solving the problem]

[0019] According to one embodiment, there is provided a surface-treated inorganic particle comprising an inorganic particle and a metal-organic framework bonded to the surface of the inorganic particle, wherein catechins form the framework of the metal-organic framework.

[0020] The catechins can include epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, catechin, catechin gallate, gallocatechin, gallocatechin gallate, or combinations thereof.

[0021] The metals constituting the metal-organic framework can include iron, magnesium, zinc, copper, manganese, titanium, molybdenum, cerium, zirconium, barium, aluminum, calcium, yttrium, silver, gold, or a combination thereof.

[0022] The inorganic particles can include titanium dioxide, zinc oxide, iron oxide, copper oxide, aluminum oxide, zirconium oxide, cerium oxide, barium oxide, silica, mica, talc, sericite, calamine, or combinations thereof.

[0023] The inorganic particles may have a particle size of 10 nm to 100,000 nm.

[0024] According to another embodiment, there is provided a method for producing surface-treated inorganic particles, the method comprising the steps of: coordinating catechins to the surface of inorganic particles; polymerizing the coordinated catechins with metal ions; and purifying the surface-treated inorganic particles.

[0025] The step of coordinating catechins to the surfaces of the inorganic particles may include dispersing the inorganic particles in an aqueous solution using ultrasound, adding the catechins, and stirring the resulting solution.

[0026] In this case, the content of the catechins may be 20 parts by weight or less relative to 100 parts by weight of the inorganic particles added.

[0027] The step of adding inorganic particles to the aqueous solution, dispersing them using ultrasound or the like, and then adding the catechins and stirring them may be carried out at a pH value of 4 to 9, at a temperature of 10°C to 30°C, for 1 minute to 60 minutes.

[0028] The step of polymerizing the coordinated catechins with metal ions may be a step of adding the metal ions or clusters thereof to an aqueous solution in which inorganic particles having catechins coordinated to their surfaces are dispersed.

[0029] The step of adding metal ions or clusters thereof to the aqueous solution in which inorganic particles having catechins coordinately bonded to the surface thereof are dispersed may be a step of adding the metal ions or clusters thereof and then stirring the mixture at 10°C to 100°C for 1 minute to 6 hours.

[0030] The step of purifying the surface-treated inorganic particles may be a step of repeatedly filtering the particles using a filter having nano- or micro-pores or centrifuging the particles to remove the supernatant.

[0031] The catechins, metal ions, inorganic particles, etc. are as described above.

[0032] According to yet another embodiment, there is provided a dispersion in which the surface-treated inorganic particles are dispersed.

[0033] The solid content in the dispersion may be 0.1% by weight to 70% by weight based on the total amount of the dispersion.

[0034] According to yet another embodiment, there is provided a cosmetic composition comprising the surface-treated inorganic particles or the dispersion. [Effects of the Invention]

[0035] By using the surface-treated inorganic particles according to one embodiment, it is possible to provide a cosmetic composition that has excellent antioxidant properties and does not discolor even when left for a long period of time. [Brief explanation of the drawings]

[0036] [Figure 1] FIG. 1 is a schematic diagram showing a cross section of a surface-treated inorganic particle according to one embodiment (Production Example 1). [Figure 2] FIG. 1 is a schematic diagram showing the process of forming a metal-organic framework from a metal ion and an organic linker. [Figure 3] 1 is a transmission scanning electron microscope photograph of titanium dioxide nanoparticles before and after surface treatment. [Figure 4] 1 is a scanning transmission electron microscope photograph of surface-treated titanium dioxide nanoparticles. [Figure 5] 1 is a transmission scanning electron microscope photograph of titanium dioxide nanoparticles before and after surface treatment. [Figure 6] 1 is a scanning transmission electron microscope photograph of surface-treated titanium dioxide nanoparticles. [Figure 7] 1 is a graph showing the antioxidant capacity of catechins bound to titanium dioxide nanoparticles (MOF-type coordination) and catechins not bound to titanium dioxide nanoparticles. [Figure 8] 1 is a photograph taken after the cosmetic composition according to Example 1 was left at room temperature for 5 weeks. [Figure 9] 1 is a photograph taken after the cosmetic composition according to Example 1 was left at 40° C. for 5 weeks. [Figure 10] 1 is a photograph taken after the cosmetic composition according to Comparative Example 1 was left at room temperature for 5 weeks. [Figure 11] 1 is a photograph taken after the cosmetic composition according to Comparative Example 1 was left at 40° C. for 5 weeks. DETAILED DESCRIPTION OF THE INVENTION

[0037] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to exemplary embodiments thereof so that those skilled in the art can easily implement and practice the present invention. However, as the present invention may be embodied in many different forms, it is not limited to the embodiments set forth herein.

[0038] In this specification, when a part such as a layer, film, region, or plate is said to be "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where there is another part between them. Conversely, when a part is said to be "directly on" another part, it means that there is no other part between them.

[0039] In this specification, unless otherwise defined, "combination" means a mixture or copolymerization, "copolymerization" means block copolymerization or random copolymerization, and "copolymer" means block copolymerization or random copolymerization.

[0040] In this specification, unless otherwise defined, catechins refer to eight types of catechins, which are composed of four epicatechins and four non-epicatechins, and the four epicatechins refer to epigallocatechin, epicatechin, epigallocatechin gallate, and epicatechin 3-O-gallate, and the other four non-epicatechins constituting the eight catechins refer to gallocatechin, catechin, gallocatechin gallate, and catechin gallate.

[0041] The surface-treated inorganic particles according to one embodiment will be described below.

[0042] In one embodiment, surface-treated inorganic particles are provided, the inorganic particles comprising a metal-organic framework bonded to the surface of the inorganic particles, wherein catechins form the framework of the metal-organic framework. More specifically, in one embodiment, the inorganic metal oxide is surface-treated by coordinating a metal-organic framework to metal atoms on the surface of the inorganic metal oxide particles, and the catechins form the framework of the metal-organic framework.

[0043] A metal-organic framework (MOF) refers to a one-, two-, or three-dimensional organic / inorganic hybrid (coordination compound) formed by coordination bonding between a metal ion or a cluster of the metal ion and an organic molecule. While MOFs are generally formed through the interaction of catechins with metal ions, the present inventors used an unconventional method to form the MOF on the surface of inorganic particles. In other words, they first induced a coordination bond between the inorganic particles and catechins, and then formed the MOF on the surface of the inorganic particles. In other words, the MOF according to one embodiment is formed through the interaction of catechins with both inorganic particles and metal ions (or clusters thereof).

[0044] Coordination compounds are materials formed by combining metal ions or their clusters with other neutral or negatively charged molecules. MOFs with coordinatively unsaturated sites (CUS) allow inorganic connectors to contain functional groups or exhibit semiconducting properties. In addition to the inherent properties of CUS, MOFs can also be used as base materials for catalytic activity and the creation of adsorption centers. A more well-known application of MOFs is their significantly higher porosity than zeolites. By using various internal designs and appropriate synthesis and functional groups, MOF nanopores can be used to store carbon dioxide, a major source of air pollution, or hydrogen, a fuel cell raw material, or as various catalysts. Furthermore, MOF pores can be designed to contract and deform in response to light or heat, allowing them to be used for the storage and release of dyes and drugs.

[0045] On the other hand, catechins, a type of polyphenol, are beneficial substances that possess strong antioxidant properties and can delay aging caused by cell damage in the human body, as mentioned above. Chemically, catechins have a molecular structure composed of two or more phenolic structures (benzene rings substituted with two or more hydroxyl groups) substituted with two or more hydroxyl groups, allowing for easy coordination bonding. Therefore, the inventors believed that by attaching catechins to MOFs, it would be possible to develop cosmetic compositions with excellent antioxidant properties and reduced discoloration even after prolonged storage. After extensive trial and error, they completed the present invention. In general, research on metal-organic frameworks has been intensified in the application of the pores within the frameworks, and in light of this, cases have been reported in which catechins are supported within the pores. However, these methods merely support catechins within the metal-organic frameworks, failing to achieve the stabilization effect of the unstable catechins. Therefore, organic reducing agents or other agents that stabilize catechins are often used in conjunction with these methods. However, even if an organic reducing agent or the like is additionally used, the stabilizing effect is limited, and discoloration of catechins cannot be effectively inhibited for a long period of time.

[0046] As a result of numerous experiments and studies, the inventors have found that when the catechins are not supported in the nanopores within the organic-metal framework, but are instead formed as the framework of the organic-metal framework and coated (coordinate bonded) on the surface of inorganic particles, specifically the surface of an inorganic metal oxide, a hydrophilic coating film is easily formed on the inorganic metal oxide, eliminating the strong cohesion between the inorganic metal oxides and enabling stable dispersion at high concentrations in an aqueous phase. At the same time, they have also confirmed that discoloration of the catechins that occurs during long-term storage is strongly suppressed, thereby maintaining excellent appearance and stable antioxidant performance.

[0047] On the other hand, catechins must be capable of forming coordinate bonds with inorganic particles, specifically inorganic metal oxides, and since catechins have functional groups capable of forming coordinate bonds with metals, a metal-organic framework having the catechin as a skeleton, which is a type of coordination compound, can be easily formed on the surface of inorganic metal oxide particles, which are mainly used in cosmetic compositions, using the catechins.

[0048] As described above, metal-organic frameworks have nanopores and a porosity much higher than that of zeolites. By appropriate synthesis or addition of functional groups, metal-organic frameworks can store hydrogen within the nanopores or be used as a catalyst or a basis for generating adsorption centers. Therefore, they have been studied for use in reactive catalysts and fuel cells. Furthermore, they have also been studied as porous nanocarriers for drug delivery, thin films for controlling drug permeation rates, and antibacterial and hydrophilic surface treatment techniques using tannic acid, a polyphenolic component that easily forms coordinate bonds. The present inventors confirmed that such metal-organic frameworks can be synthesized using only natural substances (e.g., catechins) that can form coordinate bonds in aqueous solutions and trace amounts of metal ions or their clusters. Using this, they first mixed the catechin component, a polyphenol, with inorganic metal oxide particles to form coordinate bonds on the surface, and then mixed polyvalent metal ions to grow a metal-organic framework thin film with the catechin component as the framework. They then confirmed whether or not a thin film was formed, and confirmed the dispersion stability, light absorption properties, antioxidant activity, and discoloration stability, which led to the completion of the present invention.

[0049] For example, the catechins may include eight types of catechins, specifically epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, catechin, catechin gallate, gallocatechin, gallocatechin gallate, or a combination thereof, and more specifically, the catechins may include epicatechin, epigallocatechin gallate, catechin, gallocatechin gallate, or a combination thereof.

[0050] For example, the metals constituting the metal-organic framework can include, but are not necessarily limited to, iron, magnesium, zinc, copper, manganese, titanium, molybdenum, cerium, zirconium, barium, aluminum, calcium, yttrium, silver, gold, or combinations thereof.

[0051] For example, the inorganic particles may include, but are not necessarily limited to, titanium dioxide, zinc oxide, iron oxide, copper oxide, aluminum oxide, zirconium oxide, cerium oxide, barium oxide, silica, mica, talc, sericite, calamine, or combinations thereof.

[0052] For example, the inorganic particles may have a particle size of 10 nm to 100,000 nm, such as 10 nm to 1,000 nm, for example, 1,000 nm to 50,000 nm. That is, the inorganic particles, both nanometer-sized and micrometer-sized, can have excellent dispersion stability in an aqueous phase.

[0053] Another embodiment provides a method for producing the surface-treated inorganic particles, the method including the steps of: coordinating catechins to the surface of inorganic particles; polymerizing the coordinated catechins with metal ions; and purifying the surface-treated inorganic particles.

[0054] For example, the step of coordinating catechins to the surfaces of the inorganic particles may be a step of adding inorganic particles to an aqueous solution, dispersing them using ultrasound or the like, adding the catechins, and stirring the mixture; and the step of polymerizing the coordinated catechins with metal ions may be a step of adding the metal ions or clusters thereof to an aqueous solution in which inorganic particles having catechins coordinated to their surfaces are dispersed.

[0055] The materials used in the method for producing the surface-treated inorganic particles are all environmentally friendly. Deionized water is mixed with catechins in a specific ratio, and then inorganic metal oxide particles, such as titanium dioxide, are added to the solution. Ultrasonic waves are applied to homogeneously disperse the particles in the solvent and induce surface coordinate bonds. The mixture is then stirred again, and metal ions or metal ion clusters are added at room temperature to polymerize the organic / inorganic hybrid structure. While there are no limitations on the particle size of the inorganic metal oxide particles used, inorganic metal oxide particles with diameters ranging from about 10 nm to 100,000 nm can be used. Depending on the particle size, the amount of catechins added is preferably about 20% by weight of the inorganic metal oxide particles. That is, the content of the catechins may be 20 parts by weight or less, for example, 1 to 20 parts by weight, for example, 1 to 10 parts by weight, for example, 1 to 4 parts by weight, for example, 1 to 2 parts by weight, for example, 2 to 20 parts by weight, for example, 4 to 20 parts by weight, for example, 10 to 20 parts by weight. When the content of the catechins is less than 1 part by weight, for example, 100 parts by weight of the inorganic particles to be added, the content of the catechins is too small to form the framework of the metal-organic framework. When the content of the catechins is more than 20 parts by weight, for example, 100 parts by weight of the inorganic particles to be added, the difference in effect is small compared to when the content is 1 to 20 parts by weight, and this may be uneconomical. The step of adding inorganic particles to the aqueous solution and dispersing them using ultrasound or the like, and then adding the catechins and stirring may be carried out for 1 minute to 60 minutes at a temperature of 10°C to 30°C under conditions of a pH value of 4 to 9. Furthermore, the step of adding metal ions or clusters thereof to the aqueous solution in which the inorganic particles having catechins coordinately bonded to their surfaces are dispersed may be a step of adding the metal ions or clusters thereof and then stirring at 10°C to 100°C for 1 minute to 6 hours.In this case, the content of the metal ions or clusters thereof may be 1 part by weight or less, for example, 0.05 to 1 part by weight, for example, 0.05 to 0.5 parts by weight, for example, 0.05 to 0.2 parts by weight, for example, 0.05 to 0.1 parts by weight, for example, 0.1 to 1 part by weight, for example, 0.2 to 1 part by weight, for example, 0.5 to 1 part by weight, relative to 100 parts by weight of the inorganic particles added. The reaction rate can be controlled by changing the temperature and pH. After the synthesis of the metal-organic framework is completed, the mixture can be washed two or more times using a nano- or microporous filter or centrifuged to remove the supernatant, and then re-dispersed in water to obtain a dispersion, or the washed particles can be dried and pulverized to produce a powder.

[0056] The thickness of the "catechin-based metal-organic framework" thin film uniformly formed on metal oxide nanoparticles by the method of the present invention can be adjusted depending on the ratio of catechins to inorganic metal oxide particles used in the synthesis, and the inorganic metal oxide particles with the metal-organic framework formed on their surfaces do not aggregate even when mixed in an aqueous phase at a high weight ratio, are stably dispersible at low viscosity, and do not discolor the catechins even when stored for long periods at room temperature or high temperatures. Furthermore, while characteristic coordinate bond colors generally appear in various spectral regions depending on the type of inorganic metal oxide nanoparticles and catechins, the inorganic metal oxide particles with the "catechin-based metal-organic framework" coordinated on their surfaces using the composition used in the present invention exhibit an initial light yellowish-brown color that changes to white during aging, and have been confirmed to exhibit no color change due to oxidation of the catechin molecules even during long-term storage.

[0057] The catechins, metal ions, and inorganic particles used in the method for producing the surface-treated inorganic particles are the same as those described above in relation to the surface-treated inorganic particles, unless otherwise specified.

[0058] Yet another embodiment provides a dispersion in which the surface-treated inorganic particles are dispersed.

[0059] The solid content in the dispersion may be 0.1% by weight to 70% by weight based on the total amount of the dispersion.

[0060] Yet another embodiment provides a cosmetic composition comprising the surface-treated inorganic particles or the dispersion.

[0061] Both the dispersion and the cosmetic composition contain inorganic metal oxide particles coated with the "catechin-based metal-organic framework," which maintains the excellent antioxidant properties of catechins while preventing browning in the formulation even when left for a long period of time, thereby significantly improving the marketability of the product compared to conventional products containing catechins.

[0062] Cosmetic formulations that can be used with the surface-treated inorganic metal oxide particles include lotions, nourishing creams, nourishing lotions, eye creams, essences, cleansing creams, cleansing lotions, packs, body lotions, body creams, body essences, makeup bases, foundations, ointments, gels, creams, and patches. Ingredients other than the surface-treated inorganic metal oxide particles include oils and fats typically found in cosmetic compositions, moisturizers, emollients, surfactants, organic and inorganic pigments, organic powders, UV absorbers, preservatives such as phenoxyethanol or 1,2-hexanediol, bactericides, antioxidants, plant extracts, pH adjusters, alcohols, colorants, fragrances such as artificial fragrances, blood circulation enhancers, cooling agents, antiperspirants, and purified water. Other ingredients that may be added are not limited to these, and any of the above ingredients may be added within a range that does not impair the objectives and effects of the present invention.

[0063] When the dosage form of the present invention is a solution or emulsion, a solvent, solubilizer, or emulsifier is used as a carrier component, such as water, ethanol, isopropanol, ethyl carbonate, ethyl acetate, benzyl alcohol, benzyl benzoate, propylene glycol, 1,3-butyl glycol oil, glycerol aliphatic esters, polyethylene glycol, or sorbitan fatty acid esters.

[0064] When the dosage form of the present invention is a suspension, the carrier component may be a liquid diluent such as water, ethanol or propylene glycol, a suspending agent such as ethoxylated isostearyl alcohol, polyoxyethylene sorbitol ester and polyoxyethylene sorbitan ester, microcrystalline cellulose, aluminum metahydroxide, bentonite, agar or tragacanth.

[0065] When the dosage form of the present invention is a paste, cream or gel, the carrier component may be an animal oil, a vegetable oil, wax, paraffin, starch, tragacanth, a cellulose derivative, polyethylene glycol, silicone, bentonite, silica, talc or zinc oxide.

[0066] When the dosage form of the present invention is a powder or spray, lactose, talc, silica, aluminum hydroxide, calcium silicate, or polyamide powder is used as a carrier component, and particularly in the case of a spray, a propellant such as chlorofluorohydrocarbon, propane / butane, or dimethyl ether can be additionally contained.

[0067] As described above, the composition containing the surface-treated inorganic particles or the dispersion thereof according to one embodiment can be used not only as a cosmetic composition but also as an external skin preparation.

[0068] The formulation of the external skin preparation is not limited to these, but examples thereof include liquid application agents, sprays, lotions, gels, pastes, ointments, aerosols, powders, and transdermal absorption agents.

[0069] Pharmaceutically acceptable carriers for the topical skin preparations vary depending on the formulation, but include hydrocarbons such as petrolatum, liquid paraffin, and gelling hydrocarbons (Plastibase); animal and vegetable oils such as heavy-chain fatty acid triglycerides, lard, hard fat, and cocoa butter; higher fatty acid alcohols and fatty acids and their esters such as cetanol, stearyl alcohol, stearic acid, and isopropyl palmitate; water-soluble bases such as polyethylene glycol, 1,3-butylene glycol, glycerol, gelatin, sucrose, and sugar alcohols; emulsifiers such as glycerin fatty acid esters, polyoxyl stearate, and polyoxyethylene hydrogenated castor oil; adhesives such as acrylates and sodium alginate; propellants such as liquefied petroleum gas and carbon dioxide; and preservatives such as parahydroxybenzoates. In addition to these, stabilizers, fragrances, colorants, pH adjusters, diluents, surfactants, preservatives, antioxidants, and the like may also be added as needed. The topical skin preparations are preferably applied to senescent cells using conventional methods.

[0070] The topical skin preparation can also be applied by adhering it to a solid support, such as a wound release cover of a conventional adhesive bandage. Adhesion can be achieved by saturating the solid support with a composition according to an embodiment and then dehydrating it. For example, the adhesion of the composition according to an embodiment to the solid support can be improved by first coating the solid support with an adhesive. Examples of such adhesives include polyacrylates and cyanoacrylates. Many of these formulations are commercially available, including bandages with a non-adhesive wound release cover in the form of a perforated plastic film (Smith & Nephew Ltd.); Johnson & Johnson's BAND-AID in the form of a thin strip, patch, spot, or flexible strip; Curity CURAD Ouchless bandage from Colgate-Palmolive Co. (Kendall); and STIK-TITE elastic strip from American White Cross Laboratories Inc.

[0071] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the following examples. The present invention will be described in detail below with reference to the following examples. However, these examples are for the purpose of specifically explaining the present invention, and the scope of the present invention is not limited to these examples.

[0072] (Manufacturing example) Fabrication of titanium dioxide particles surface-treated with metal-organic frameworks (Production Example 1) Using titanium dioxide nanoparticles as seeds, composite nanoparticles were synthesized in which epigallocatechin gallate (EGCG), a catechin, was coated on the surface of titanium dioxide. First, TiO2 nanoparticles were added to an aqueous phase with EGCG (see Table 1 below) under weakly basic conditions at pH 8, and ultrasonic waves were applied at room temperature for approximately 5 minutes to induce surface coordination bonds. This mixture was then mixed with FeCl3 as a metal ion and stirred at 30°C for 30 minutes to form a metal-organic framework (MOF). The resulting EGCG-MOF-TiO2 dispersion was purified by filtering the powder through an aluminum oxide filter with pores of 200 nm or less, and then redispersing the resulting powder in purified water twice.

[0073] [Table 1] (unit: parts by weight)

[0074] (Production Example 2) The same procedure as in Production Example 1 was carried out, except that zinc oxide was used as the seed instead of titanium dioxide.

[0075] (Production Example 3) The same procedure as in Production Example 1 was carried out, except that gallocatechin gallate (GCG) was used instead of EGCG.

[0076] Preparation of cosmetic compositions: Examples 1 to 3 and Comparative Example 1 A cosmetic composition in the form of a W / O emulsion was prepared using the formulation in Table 2 below by a conventional method.

[0077] Specifically, in Examples 1 to 3 and Comparative Example 1, the oil phase component and powder component were heated to 75°C and uniformly mixed according to the composition shown in Table 2 below, and then the mixture was uniformly mixed with the aqueous phase component while stirring while maintaining the temperature at 75°C to produce a W / O emulsion.

[0078] [Table 2]

[0079] Preparation of cosmetic compositions: Examples 4 to 6 and Comparative Example 2 A cosmetic composition in the form of a paste powder was prepared using the formulation shown in Table 3 below in a conventional manner.

[0080] Specifically, in Examples 4 to 6 and Comparative Example 2, the powder components were mixed for 30 minutes using a Henschel mixer according to the compositions shown in Table 3 below, the oil phase components were heated to 80°C to dissolve uniformly, and the dissolved oil phase components were added to the powder components by spraying while mixing, and then the mixture was mixed for 30 minutes, pulverized in a pulverizer, and filtered to produce face powders.

[0081] [Table 3]

[0082] (evaluation) Experimental Example 1: Confirmation of surface coating film formation (TEM) The surfaces of the titanium dioxide nanoparticles surface-treated according to Preparation Example 1 were observed using a transmission scanning electron microscope (Tecnai F20 G2), and the results are shown in Figures 3 to 6. Figures 3 to 6 confirm that, unlike before coating (surface treatment), a uniform nanometer-thick metal-organic framework (MOF) thin film was formed on the surface of the titanium dioxide nanoparticles after coating (surface treatment).

[0083] Experimental Example 2: Radical scavenging rate (antioxidant capacity) evaluation The antioxidant activity of EGCG bound to titanium dioxide nanoparticles in Preparation Example 1 was confirmed using the DPPH test. Even if EGCG is stabilized by the formation of a metal-organic framework (MOF), its effectiveness may be halved if the antioxidant activity of EGCG is lost. Therefore, the radical scavenging rate was confirmed, and the results are shown in Figure 7. Figure 7 confirms that the surface-treated titanium dioxide particles in Preparation Example 1 exhibited a radical scavenging rate of approximately 70% compared to an ECGC aqueous solution of the same concentration. This indicates that the antioxidant activity is not lost even though EGCG is not supported in the pores within the MOF but forms the MOF framework itself.

[0084] Experimental Example 3: Comparison of color stability between surface-treated and simple mixed cases The changes in hue due to storage conditions for each of the cosmetic compositions according to Example 1 and Comparative Example 1 were observed with the naked eye (observed for 5 weeks at room temperature (25°C) and high temperature (40°C), respectively), and the results are shown in Table 4 below and Figures 8 to 11. From Table 4 below and Figures 8 to 11, it can be seen that the cosmetic composition according to Comparative Example 1 showed significant browning of EGCG over time, whereas the cosmetic composition according to Example 1 showed almost no browning.

[0085] [Table 4]

[0086] ○: Even after 5 weeks, there is no visible change in color compared to before 5 weeks. ×: After 5 weeks, there is a change in color (brownish) visible to the naked eye compared to before 5 weeks.

[0087] Experimental Example 4: Dispersion Stability Evaluation The surface potential of particles indicates the strength of the repulsive force between particles, which is an index of dispersion stability. Therefore, to confirm the effect of the MOF coating thin film on the surface potential of titanium dioxide, the zeta potential was measured, and the results are shown in Tables 5 and 6 below. Table 5 below shows the surface potential measured for the composition (aqueous solution) of Example 1 as the pH changed. The surface potential increased as the pH became closer to the base. Table 6 shows the average surface potential values ​​for the compositions (aqueous solutions) of Comparative Example 1, Example 1, Example 2, and Example 3 at pH 10.

[0088] [Table 5]

[0089] [Table 6]

[0090] From Tables 5 and 6, it can be seen that the surface potential values ​​of the titanium dioxide particles in the cosmetic compositions according to Examples 1 to 3 exhibit a greater negative charge value than the surface potential value of the titanium dioxide particles in the cosmetic composition according to Comparative Example 1, and that the negative surface potentials increase in the order of Example 1 < Example 2 < Example 3. This confirms that the surface-treated inorganic particles according to one embodiment have better dispersion stability than inorganic particles that are not surface-treated, and that such dispersion stability can be adjusted by the type of inorganic particles and the type of polyphenols that form the skeleton of the metal-organic framework.

[0091] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

Claims

1. The present invention comprises inorganic particles and a metal-organic framework bonded to the surfaces of the inorganic particles, the inorganic particles include titanium dioxide, zinc oxide, iron oxide, copper oxide, aluminum oxide, zirconium oxide, cerium oxide, barium oxide, silica, mica, talc, calamine, or a combination thereof; the metal constituting the metal-organic framework comprises iron, magnesium, zinc, manganese, titanium, molybdenum, cerium, zirconium, barium, aluminum, calcium, yttrium, or a combination thereof; The surface-treated inorganic particles have a metal-organic framework skeleton formed of catechins.

2. 2. The surface-treated inorganic particles according to claim 1, wherein the catechins comprise epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, catechin, catechin gallate, gallocatechin, gallocatechin gallate, or a combination thereof.

3. 2. The surface-treated inorganic particles according to claim 1, wherein the inorganic particles have a particle size of 10 nm to 100,000 nm.

4. A step of coordinating catechins to the surface of inorganic particles; polymerizing the coordinated catechins with metal ions; and purifying the surface-treated inorganic particles; Including, the inorganic particles include titanium dioxide, zinc oxide, iron oxide, copper oxide, aluminum oxide, zirconium oxide, cerium oxide, barium oxide, silica, mica, talc, calamine, or a combination thereof; The metal comprises iron, magnesium, zinc, manganese, titanium, molybdenum, cerium, zirconium, barium, aluminum, calcium, yttrium, or a combination thereof; A method for producing surface-treated inorganic particles.

5. The step of coordinating catechins to the surface of the inorganic particles includes: The method for producing surface-treated inorganic particles according to claim 4, comprising the steps of dispersing inorganic particles in an aqueous solution, adding the catechins, and stirring the mixture.

6. The step of polymerizing the coordinated catechins with a metal ion comprises:

6. The method for producing surface-treated inorganic particles according to claim 5, comprising the step of adding the metal ions or clusters thereof to an aqueous solution in which inorganic particles having catechins coordinated to the surface thereof are dispersed.

7. The method for producing surface-treated inorganic particles according to claim 5 , wherein the content of the catechins is 20 parts by weight or less relative to 100 parts by weight of the inorganic particles added.

8. 6. The method for producing surface-treated inorganic particles according to claim 5, wherein the step of adding and dispersing inorganic particles in the aqueous solution, adding the catechins, and stirring the mixture is carried out at a pH of 4 to 9, at a temperature of 10°C to 30°C, and for 1 minute to 60 minutes.

9. 7. The method for producing surface-treated inorganic particles according to claim 6, wherein the step of adding metal ions or clusters thereof to the aqueous solution in which the inorganic particles having catechins coordinately bonded to the surfaces thereof are dispersed comprises adding the metal ions or clusters thereof and then stirring the mixture at 10°C to 100°C for 1 minute to 6 hours.

10. 5. The method for producing surface-treated inorganic particles according to claim 4, wherein the step of purifying the surface-treated inorganic particles comprises repeatedly filtering the particles using a filter having nano- or micro-pores or centrifuging the particles to remove a supernatant.

11. 5. The method for producing surface-treated inorganic particles according to claim 4, wherein the catechins include epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, catechin, catechin gallate, gallocatechin, gallocatechin gallate, or a combination thereof.

12. The method for producing surface-treated inorganic particles according to claim 4, wherein the inorganic particles have a particle size of 10 nm to 100,000 nm.

13. A dispersion in which the surface-treated inorganic particles according to claim 1 are dispersed.

14. 14. The dispersion of claim 13, wherein the solid content in the dispersion is 0.1% to 70% by weight, based on the total weight of the dispersion.

15. A cosmetic composition comprising the surface-treated inorganic particles according to claim 1 or the dispersion according to claim 13.

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