Ultraviolet blocking composite structure, manufacturing method therefor, and ultraviolet blocking cosmetic composition comprising same

Abstract

The present invention relates to an ultraviolet blocking composite structure and an ultraviolet blocking cosmetic composition comprising same and, more specifically, to an ultraviolet blocking composite structure, which has excellent blocking performance for broadband ultraviolet rays including UVA and UVB and has less cytotoxic effects caused by photoactivity.

Description

UV-blocking composite structure, method for producing the same, and UV-blocking cosmetic composition comprising the same

[0001] The present invention relates to a composite structure for UV protection, a method for preparing the same, and a cosmetic composition for UV protection comprising the same. The present invention claims the benefit of Korean Patent Application No. 10-2024-0038561, filed with the Korean Intellectual Property Office on March 20, 2024, the entire contents of which are incorporated herein by reference.

[0002] Ultraviolet (UV) rays in sunlight are known to accelerate photoaging and painful erythema of the human dermis. UV rays reaching humans are classified as UVB (290-320 nm) and UVA (320-400 nm). UVA is a long-wave UV ray that can penetrate clothing and human skin more deeply. Its relatively low energy level does not cause acute skin inflammation, but it can affect skin aging over time. UVB is a medium-wave UV ray that is mostly absorbed by the epidermis. However, its high energy level can cause blisters and rashes, and long-term exposure can cause erythema, inflammation, and skin aging.

[0003] Sunscreen formulations are generally divided into organic and inorganic types. Organic sunscreens have limitations, such as short photostability and the potential for skin irritation. Zinc oxide (ZnO) nanoparticles and titanium dioxide (TiO2) nanoparticles are inorganic UV-blocking agents known for their superior UV-scattering properties, blocking UVA and UVB rays, respectively.

[0004] However, it is known that ZnO and TiO2 nanoparticles can absorb ultraviolet rays and exhibit photocatalytic activity, which can generate reactive oxygen species (ROS), which can cause harmful effects on the body, such as DNA strand damage, inflammatory responses, apoptosis, and cellular abnormalities. Furthermore, nanoparticles with a particle size of less than 100 nm, unlike non-nanoparticles, can penetrate the stratum corneum of the skin and be absorbed into the body, which remains a potential risk. Meanwhile, a method of coating nanoparticles has been proposed in an attempt to block the cytotoxicity caused by the photocatalytic activity of ZnO and TiO2 nanoparticles, but the photocatalytic effect, which is most prominent in anatase TiO2, could not be completely avoided.

[0005] In addition, it has been pointed out that inorganic UV-blocking materials based on ZnO and TiO2 are difficult to disperse and dissolve, and therefore UV-blocking cosmetics containing them have a white cloudy appearance, making them less pleasant to use.

[0006] The technical problem to be achieved by the present invention is to provide a UV blocking material that can provide broadband UV protection including UVA and UVB and is safe from concerns about cytotoxicity due to reactive oxygen species (ROS).

[0007] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the description below.

[0008] One embodiment of the present invention provides a composite structure for blocking ultraviolet rays, comprising: a hollow core; two or more porous shell layers; and a hollow layer positioned between the two or more porous shell layers, wherein the porous shell layer comprises a conjugate of zinc oxide (ZnO) nanoparticles and titanium dioxide (TiO2) nanoparticles.

[0009] Another embodiment of the present invention provides a method for manufacturing the above ultraviolet-blocking composite structure, comprising the steps of: preparing a porous carbon support; absorbing zinc and titanium into the porous carbon support; and calcining the porous carbon support into which zinc and titanium have been absorbed to obtain the above composite structure.

[0010] Another embodiment of the present invention provides a cosmetic composition for blocking ultraviolet rays, comprising the above-described composite structure for blocking ultraviolet rays.

[0011] A composite structure for blocking ultraviolet rays according to one embodiment of the present invention may have excellent blocking performance against broadband ultraviolet rays including UVA and UVB.

[0012] A composite structure for blocking ultraviolet rays according to one embodiment of the present invention may have excellent photostability.

[0013] A composite structure for blocking ultraviolet rays according to one embodiment of the present invention can reduce the formation of reactive oxygen species (ROS) due to photoactivity and significantly reduce cytotoxicity.

[0014] A cosmetic composition for blocking ultraviolet rays according to one embodiment of the present invention may have a high sun protection factor (SPF) and may prevent whitening.

[0015] The effects of the present invention are not limited to the effects described above, and effects not mentioned will be clearly understood by those skilled in the art from the present specification and the attached drawings.

[0016] Figure 1 is a schematic diagram of a cross-section of a composite structure for blocking ultraviolet rays according to one embodiment of the present invention.

[0017] Figure 2 is a diagram showing the ultraviolet ray blocking and electron transfer mechanism in a conjugate of zinc oxide (ZnO) nanoparticles and titanium dioxide (TiO2) nanoparticles.

[0018] Figure 3 is a drawing showing SEM images (a, b, c), TEM images (d, e, f), STEM images (g), and EDS mapping images (h, i, j) of the composite structure of Example 1.

[0019] Figure 4 shows an HR-TEM image (a) of the composite structure of Example 1 and an enlarged HR-TEM image (b) of the outer shell layer.

[0020] Figure 5 is a drawing showing an XRD pattern for the composite structure of Example 1.

[0021] Figure 6 is a drawing showing an XPS spectrum for the composite structure of Example 1.

[0022] Figure 7 is a drawing showing the UV-vis absorbance spectra for the composite structure of Example 1, the ZnO nanoparticles of Comparative Example 1, and the TiO2 nanoparticles of Comparative Example 2.

[0023] Figure 8 is a drawing showing the BET (Brunauer-Emmett-Teller) isotherm (a) for the composite structure of Example 1 and the size distribution (b) of pores present in the porous shell layer of the composite structure of Example 1.

[0024] Figure 9 is a diagram showing UV-vis absorbance spectra before and after 5 hours of UV simulation for the composite structure of Example 1, ZnO nanoparticles of Comparative Example 1, TiO2 nanoparticles of Comparative Example 2, and nanoparticle mixture of Comparative Example 3.

[0025] Figure 10 is a drawing showing the decomposition performance of the composite structure of Example 1, ZnO nanoparticles of Comparative Example 1, TiO2 nanoparticles of Comparative Example 2, and nanoparticle mixture of Comparative Example 3 for methylene blue.

[0026] Figure 11 is a diagram showing cell viability for DMEM medium containing the composite structure of Example 1, ZnO nanoparticles of Comparative Example 1, TiO2 nanoparticles of Comparative Example 2, and nanoparticle mixture of Comparative Example 3 at concentrations of 1, 2, 5, and 10 μg / mL, respectively.

[0027] Figure 12 is a photograph of a cream-type sunscreen manufactured in Comparative Example 7, Example 2, and Example 3.

[0028] Figure 13 is a drawing showing SEM images for Comparative Example 7 (a, b) and Example 2 (c, d).

[0029] Figure 14 is a drawing showing the results of transmittance measurements for the UV blockers of Example 2, Comparative Examples 4 to 6, and Reference Example.

[0030] Figure 15 is a drawing showing the results of a whitening phenomenon evaluation experiment of the sunscreen of Example 2 on subjects with various skin colors.

[0031] Throughout this specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0032] Throughout this specification, when it is said that an element is "on" another element, this includes not only cases where the element is in contact with the other element, but also cases where another element exists between the two elements.

[0033] Throughout this specification, the unit “parts by weight” may mean the weight ratio between each component.

[0034] Throughout this specification, “A and / or B” means “A and B, or A or B.”

[0035] One embodiment of the present invention provides a composite structure for blocking ultraviolet rays, comprising: a hollow core; two or more porous shell layers; and a hollow layer positioned between the two or more porous shell layers, wherein the porous shell layer comprises a conjugate of zinc oxide (ZnO) nanoparticles and titanium dioxide (TiO2) nanoparticles.

[0036] A composite structure for blocking ultraviolet rays according to one embodiment of the present invention may have excellent blocking performance against broadband ultraviolet rays including UVA and UVB.

[0037] A composite structure for blocking ultraviolet rays according to one embodiment of the present invention may have excellent photostability. That is, the composite structure for blocking ultraviolet rays may have an excellent characteristic in which the ultraviolet absorption ability does not change even when exposed to sunlight.

[0038] According to one embodiment of the present invention, a composite structure for blocking ultraviolet rays includes a porous shell layer containing a conjugate of zinc oxide (ZnO) nanoparticles and titanium dioxide (TiO2) nanoparticles, thereby reducing the formation of reactive oxygen species (ROS) due to photoactivity and significantly reducing cytotoxicity. Specifically, the conjugated ZnO and TiO2 nanoparticles can be photogenerated by each other. - / h + It can act as a recombination site of the pair, so that the formation of reactive oxygen species (ROS) can be significantly reduced.

[0039] The composite structure for blocking ultraviolet rays according to one embodiment of the present invention can be well dispersed in a matrix of an aqueous phase, a fatty phase, or an emulsion phase, and there can be no agglomeration of particles.

[0040] Figure 1 is a schematic diagram of a cross-section of a composite structure for blocking ultraviolet rays according to one embodiment of the present invention.

[0041] Referring to FIG. 1, a composite structure for blocking ultraviolet rays according to one embodiment of the present invention may be spherical in shape and has a multilayer core-shell structure including a hollow core, two or more porous shell layers surrounding the hollow core, and a hollow layer positioned between the two or more porous shell layers.

[0042] According to one embodiment of the present invention, a composite structure for blocking ultraviolet rays may include a porous shell layer having two or more layers and five or fewer layers. More specifically, the composite structure may include a porous shell layer having two, three, four, or five layers.

[0043] In the present specification, the two or more porous shell layers included in the composite structure may be referred to as a first porous shell layer, a second porous shell layer, a third porous shell layer, etc. in the order of proximity to the hollow core, and similarly, a hollow layer located between the two or more porous shell layers may also be referred to as a first hollow layer, a second hollow layer, etc.

[0044] According to one embodiment of the present invention, the composite structure is spherical and may have an average diameter of 0.1 µm to 5 µm. More specifically, the average diameter of the composite structure may be 0.1 µm to 3 µm, 0.1 µm to 2 µm, 0.1 µm to 1 µm, 0.1 µm to 0.8 µm, 0.2 µm to 1 µm, 0.2 µm to 0.8 µm, 0.2 µm to 0.6 µm, 0.3 µm to 1 µm, 0.3 µm to 0.8 µm, 0.3 µm to 0.6 µm, or 0.3 µm to 0.5 µm. Since the composite structure is a fine particle having an average diameter satisfying the above-described range, it cannot pass through the outer layer of the skin (stratum corneum) and there is no harmful risk due to absorption into the body.

[0045] According to one embodiment of the present invention, the porous shell layer includes a conjugate of zinc oxide (ZnO) nanoparticles and titanium dioxide (TiO2) nanoparticles.

[0046] Figure 2 is a diagram showing the ultraviolet ray blocking and electron transfer mechanism in a conjugate of zinc oxide (ZnO) nanoparticles and titanium dioxide (TiO2) nanoparticles.

[0047] Referring to Fig. 2, the band gaps of ZnO nanoparticles and TiO2 nanoparticles are very similar, and the conduction band of TiO2 is located higher than that of ZnO. Therefore, when ZnO nanoparticles and TiO2 nanoparticles come into contact with each other, the Fermi level in the TiO2 crystal lattice shifts for energy balance, and a type II heterojunction is formed. A potential barrier is formed at the junction (interface) of the two solid-state semiconductor materials as a result of the bending of the energy band. In addition, the bonded ZnO and TiO2 nanoparticles transmit photogenerated e to each other. - / h + It can act as a recombination site for the pair, which can significantly reduce the formation of reactive oxygen species (ROS).

[0048] The above ZnO nanoparticles may have a wurtzite crystal structure. The above TiO2 nanoparticles may have at least one crystal structure selected from anatase, rutile, and brookite, and preferably have a crystal structure of anatase, rutile, or a mixture of anatase and rutile.

[0049] The average diameter of each of the ZnO nanoparticles and the TiO2 nanoparticles may range from 1 to 100 nm.

[0050] According to one embodiment of the present invention, the porous shell layer may include zinc oxide (ZnO) and titanium dioxide (TiO2) in an atomic ratio of 1:1 to 1:3.

[0051] According to one embodiment of the present invention, the band gap of the composite structure may be 4 eV or more. Since the band gap of the composite structure is 4 eV or more, the composite structure may have excellent blocking performance against broadband ultraviolet rays including UVA and UVB. More specifically, the band gap of the composite structure may be 4 eV or more and 10 eV or less.

[0052] According to one embodiment of the present invention, the porous shell layer may include mesopores having a pore diameter in the range of 2 nm to 50 nm and macropores having a pore diameter in the range of more than 50 nm to 1000 nm. Since the porous shell layer includes the mesopores and macropores, it can appropriately absorb sunlight and prevent reflection of visible light, thereby preventing unwanted white turbidity.

[0053]

[0054] Another embodiment of the present invention provides a method for manufacturing the above ultraviolet ray blocking composite structure, comprising the steps of: preparing a porous carbon support; absorbing (adsorbing) zinc and titanium onto the porous carbon support; and calcining the porous carbon support into which zinc and titanium have been absorbed (adsorbed) to obtain the above composite structure.

[0055] According to one embodiment of the present invention, the porous carbon support may be carbon microspheres (CMS).

[0056] The above carbon microspheres contain a large number of mesopores and are rich in functional groups such as OH, -C=O, and -COC, so they can absorb metal ions through electrostatic interactions.

[0057] According to one embodiment of the present invention, the average diameter of the carbon microspheres may be 0.1 μm to 5 μm. Specifically, the average diameter of the carbon microspheres may be 0.1 μm to 3 μm, 0.1 μm to 2 μm, 0.1 μm to 1 μm, 0.1 μm to 0.8 μm, 0.2 μm to 1 μm, 0.2 μm to 0.8 μm, 0.2 μm to 0.6 μm, 0.3 μm to 1 μm, 0.3 μm to 0.8 μm, 0.3 μm to 0.6 μm, or 0.3 μm to 0.5 μm. By satisfying the above-described range of the average diameter of the carbon microspheres, a composite structure for blocking ultraviolet rays that cannot pass through the outer layer of the skin (stratum corneum) and does not pose a harmful risk due to absorption into the body can be manufactured.

[0058] According to one embodiment of the present invention, the carbon microspheres may be manufactured by a hydrothermal synthesis method using a sugar compound and sodium bicarbonate as disclosed in Korean Patent No. 10-2316874 B1, but the method for obtaining the carbon microspheres is not limited thereto. The carbon microspheres may also be manufactured by a known method other than the hydrothermal synthesis method using other carbohydrates, fats, proteins, or polymeric substances known to be capable of manufacturing carbon microspheres.

[0059] According to one embodiment of the present invention, in the step of absorbing zinc and titanium into the porous carbon support, zinc and titanium may be sequentially absorbed into the porous carbon support or zinc and titanium may be absorbed simultaneously.

[0060] According to one embodiment of the present invention, the absorption of zinc or titanium into the porous carbon support can be performed by a step of mixing the porous carbon support with a zinc precursor solution or a titanium precursor solution. The simultaneous absorption of zinc and titanium into the porous carbon support can be performed by mixing the porous carbon support, a zinc precursor solution, and a titanium precursor solution.

[0061] Specifically, the method of mixing the precursor solution and the porous carbon support may be to add the porous carbon support to the precursor solution and disperse the porous carbon support in the precursor solution through ultrasonic treatment.

[0062] According to one embodiment of the present invention, when zinc and titanium are sequentially absorbed into the porous carbon support, a step of obtaining a porous carbon support in which zinc or titanium is absorbed, washing it, and then drying it may be further included between the mixing process with each precursor solution.

[0063] According to one embodiment of the present invention, each of the zinc precursor solution and the titanium precursor solution may include a solvent together with the zinc precursor and the titanium precursor.

[0064] According to one embodiment of the present invention, the zinc precursor and the titanium precursor may each independently be at least one selected from the group consisting of nitrate, ammonium salt, sulfate, and chloride, or a hydrate thereof. Specifically, it is preferably a nitrate or a chloride, or a hydrate thereof. For example, the zinc precursor may be ZnCl2, and the titanium precursor may be TiCl4.

[0065] According to one embodiment of the present invention, after mixing the zinc precursor solution and the porous carbon support, maturation may be performed before obtaining a zinc-absorbed porous carbon support. This maturation process can prevent the formation of aggregates and obtain a zinc-absorbed porous carbon support of uniform size.

[0066] Similarly, after mixing the titanium precursor solution and the porous carbon support, maturation can be performed before obtaining a porous carbon support with titanium absorbed. This maturation process can prevent the formation of aggregates and obtain a porous carbon support with titanium absorbed of a uniform size.

[0067] According to one embodiment of the present invention, the aging may be performed at a temperature of 20°C to 60°C, 20°C to 50°C, 30°C to 60°C, 20°C to 40°C, 30°C to 50°C, 40°C to 60°C, 30°C to 40°C, or 40°C to 50°C for 15 to 72 hours, 15 to 40 hours, 15 to 35 hours, 20 to 35 hours, 15 to 30 hours, or 20 to 30 hours. When the aging is performed within the above time and temperature ranges, zinc and titanium can be well absorbed onto the porous carbon support, so that the distribution of zinc oxide (ZnO) nanoparticles and titanium dioxide (TiO2) nanoparticles in the finally manufactured composite structure can be uniform. By controlling the maturation time within the above-described time range, the number of porous shell layers included in the composite structure can be controlled to be 2 or more layers and 5 or less layers.

[0068] According to one embodiment of the present invention, the carbon support can be removed during the calcination process, and thus the ultraviolet-blocking composite structure of the present invention can be obtained.

[0069] According to one embodiment of the present invention, the calcination can be performed at a temperature of 400°C to 600°C in an air atmosphere for 1 to 5 hours.

[0070] Another embodiment of the present invention provides a cosmetic composition for blocking ultraviolet rays, comprising a composite structure for blocking ultraviolet rays according to an embodiment of the present invention.

[0071] A cosmetic composition for blocking ultraviolet rays according to one embodiment of the present invention can have a high ultraviolet protection factor (SPF) and prevent whitening by including the above-described ultraviolet ray blocking complex structure.

[0072] According to one embodiment of the present invention, the composite structure for blocking ultraviolet rays may be included in an amount of 0.1 to 20 wt% based on the total weight of the composition.

[0073] A cosmetic composition for blocking ultraviolet rays according to one embodiment of the present invention can satisfy a sun protection factor (SPF) value of 40 or more, 45 or more, 50 or more, 55 or more, 60 or more, or 65 or more.

[0074] The above UV protection index value may be a value calculated by a standard formula represented by the following mathematical expression 1.

[0075] [Mathematical Formula 1]

[0076]

[0077] (T λ is the spectral transmittance of the sample, and S λ is the solar spectral irradiance, and E λ is the CIE Erythemal spectral effectiveness.)

[0078] The cosmetic composition for blocking ultraviolet rays according to one embodiment of the present invention can be manufactured in any formulation commonly manufactured in the art.

[0079] A cosmetic composition for blocking ultraviolet rays according to one embodiment of the present invention may include any other ingredients commonly used in the field of ultraviolet ray blocking cosmetics, except for the ultraviolet ray blocking functional ingredient including the above-described ultraviolet ray blocking composite structure.

[0080] For example, the above-described UV-blocking cosmetic composition may include ingredients such as organic solvents, solubilizers, thickeners, gelling agents, softeners, antioxidants, suspending agents, stabilizers, foaming agents, fragrances, surfactants, purified water, moisturizers, ionic or nonionic emulsifiers, fillers, metal ion sequestering agents, chelating agents, preservatives, humectants, essential oils, dyes, pigments, hydrophilic or lipophilic active agents, sweeteners, vitamins, and antioxidants, depending on the formulation or function of the final product.

[0081] Hereinafter, the present invention will be described in detail using examples. However, the examples according to the present invention may be modified in various ways, and the scope of the present invention is not limited to the examples described below. The examples in this specification are provided to more fully explain the present invention to those of ordinary skill in the art.

[0082] Reagents and Materials

[0083] All reagents were purchased from Sigma-Aldrich Co., Ltd., Korea, and used without further purification. Zinc chloride (ZnCl2) and titanium tetrachloride (TiCl4) were used as zinc and titanium metal precursors, respectively.

[0084] Example 1. Preparation of composite structures (TiO2@ZnO PHMMs) for UV protection

[0085] Carbon microspheres were prepared by pre-synthesizing them under hydrothermal conditions using sucrose. Specifically, 13 g of sucrose was added to 31 ml of deionized water and stirred at 500 rpm for 30 minutes. Then, 30.05 g of NaHCO was added and stirred for 10 minutes to prepare a solution. This solution was transferred to a 250 ml hydrothermal reactor, sealed in a Teflon container, and reacted at 200 °C for 130 minutes to obtain a brown product. The resulting product was washed five times with deionized water and ethanol and dried at 80 °C for 12 hours to obtain carbon microspheres.

[0086] In the first step, 2 g of the synthesized carbon microspheres were dissolved in 50 mL of a 3 M ZnCl2 solution, and the microspheres were dispersed by sonication for 5 minutes. The container containing the dispersion was transferred to an oil bath at 50°C, stirred for 24 hours, and then filtered. The filtered residue was washed twice with deionized water (DI water) and then twice with absolute ethanol, and dried at 70°C for 24 hours to obtain a black powder containing zinc-absorbed carbon microspheres.

[0087] In the second step, 1.5 g of the black powder was dispersed in 50 mL of a 3 M TiCl4 solution, the dispersion was stirred at 50°C for 24 hours, and then filtered. The filtered residue was washed three times with deionized water and then twice with anhydrous ethanol, and dried at 70°C for 24 hours to obtain a powder containing carbon microspheres absorbed with zinc and titanium.

[0088] In the third step, in order to calcinate the carbon microspheres, the powder obtained in the second step was heated to 500°C at 1°C / min in an air atmosphere, maintained at 500°C for 3 hours, and then naturally cooled to room temperature to produce a white powder including the UV-blocking composite structure of the present invention.

[0089] Comparative Example 1. Zinc oxide nanoparticles (ZnO NPs)

[0090] ZnO nanoparticles, which are spherical in shape and have a diameter ranging from 40 to 100 nm, were purchased from Sigma-Aldrich, Korea.

[0091] Comparative Example 2. Titanium oxide nanoparticles (TiO2NPs)

[0092] TiO2 anatase nanoparticles with a spherical shape and a diameter ranging from 30 to 50 nm were purchased from Sigma-Aldrich, Korea.

[0093] Comparative Example 3. Mixture of zinc oxide nanoparticles and titanium oxide nanoparticles (ZnO:TiO2=1:1 NPs Mixture)

[0094] ZnO nanoparticles and TiO2 nanoparticles of Comparative Examples 1 and 2 were prepared by mixing them in a molar ratio of 1:1.

[0095] <Experimental Example 1. Characteristic Analysis of Composite Structures>

[0096] (1) Micro-shape analysis of composite structures

[0097] To analyze the microstructure of the composite structure of Example 1, a field-emission scanning electron microscope (FE-SEM, Hitachi S-4800) was used. High-resolution transmission electron microscope (HR-TEM) images were captured using a 200 kV field-emission electron gun (Tecnai G2 F20 STWIN). Prior to microscopic analysis, the sample was placed in a vacuum at 200°C overnight to remove internal gases.

[0098] Figure 3 is a drawing showing SEM images (a, b, c), TEM images (d, e, f), STEM images (g), and EDS mapping images (h, i, j) of the composite structure of Example 1.

[0099] Referring to parts (a) to (c) of Fig. 3 (SEM images), it was confirmed that the composite structure of Example 1 had a spherical particle shape and a diameter in the range of about 300 to 500 nm. This suggests that the composite structure of Example 1 is a fine particle, not a nanoparticle, and thus cannot pass through the outer layer of the skin (stratum corneum), thereby avoiding related health effects.

[0100] Referring to parts (d) to (f) (TEM image) and part (g) (STEM image) of Fig. 3, it was confirmed that the composite structure of Example 1 was composed of a hollow core, three shell layers surrounding the core, and cavities existing between the three shell layers.

[0101] Referring to parts (h) to (j) of Fig. 3 (EDS mapping image), a shell layer in which Zn, Ti, and O elements are concentrated and distributed and a cavity existing between these shell layers were confirmed.

[0102] Figure 4 shows an HR-TEM image (a) of the composite structure of Example 1 and an enlarged HR-TEM image (b) of the outer shell layer.

[0103] Referring to Fig. 4, it was confirmed that the shell layer of the composite structure was a structure in which ZnO nanoparticles were bonded to TiO2 nanoparticles to form a heterojunction. By analyzing the HR-TEM image above, it was confirmed that the nanoparticles (the part indicated as ZnO) had a lattice spacing of 0.26 nm, which is the same as the interplanar spacing of the (100) plane of ZnO having a wurtzite crystal structure, and the nanoparticles (the part indicated as TiO2) had a lattice spacing of 0.35 nm, which is the same as the interplanar spacing of the (101) plane of TiO2 having an anatase crystal structure, thereby confirming the junction in which ZnO nanoparticles were bonded to TiO2 nanoparticles.

[0104] (2) Structural analysis of composite structures (XRD)

[0105] The crystal structure of the composite structure of Example 1 was determined through X-ray diffraction analysis. Specifically, the analysis was performed using an X-ray diffractometer (PANalytical X'Pert PRO) under the conditions of Cu K radiation (0.154056 nm), an angle range of 10-80°, a step size of 0.02°, 40 kV, and 30 mA. Fig. 5 is a drawing showing the XRD pattern for the composite structure of Example 1.

[0106] Referring to Fig. 5, the XRD pattern for the composite structure of Example 1 showed six main diffraction peaks (indicated as "A") corresponding to anatase TiO2 nanoparticles, and ZnO was a minor phase. In addition, a shoulder peak was observed near the (101) peak at 2θ of 25.5°, suggesting that the distance between the diffraction crystal planes of TiO2 increased and the crystal structure changed due to ZnO. These results supported the development of the composite structure of the present invention, which improves the crystallinity of TiO2 and ZnO nanoparticles.

[0107] Furthermore, X-ray photoemission spectroscopy (XPS) was performed on the composite structure of Example 1. Fig. 6 is a diagram showing the XPS spectrum of the composite structure of Example 1.

[0108] Referring to Figure 6, the presence of three elements, zinc (Zn), titanium (Ti), and oxygen (O), was confirmed, and the strong peak observed at 36.83 eV corresponds to the Zn-O bond within the hexagonal wurtzite crystal structure, and the peak at 453.22 eV for Ti 2p corresponds to the Ti-O bond, which is a characteristic Ti present in the TiO2 anatase phase. 4+It may be attributed to. In addition, it was confirmed that Zn-O bonds exist at the lattice oxygen (O) of TiO2 and the intrinsic site within the zinc matrix through the peak indicated as O 1s in the spectrum. These XPS results strongly suggest that the composite structure according to the present invention is a heterojunction microsphere composed of crystalline ZnO and TiO2, and it was confirmed that the atomic ratio of ZnO and TiO2 is about 1.5:1.

[0109] (3) UV blocking property evaluation

[0110] The effectiveness of the composite structure as a UV blocking material was evaluated using a UV-vis spectrometer (UV-i Selection, Shimadzu Corporation, Japan). Furthermore, the band gaps for the composite structure and nanoparticles were calculated using Tauc plots. The band gap of ZnO was estimated by a direct allowed transition with n = 1 / 2, whereas the band gap of TiO2 anatase was calculated by an indirect allowed transition with n = 2. The indirect allowed transition was chosen because the composite structure contained a larger amount of TiO2 than ZnO. The UV region band of TiO2 nanoparticles is the result of an electrical transition from the valence band (generated by the O 2p state) to the transition band (generated by the Ti 3d state), whereas the UV region of ZnO nanoparticles is caused by a transition from the last occupied level (the valence band generated by the O 2p state) to the first free level in the conduction band corresponding to the Zn 4s level.

[0111] Figure 7 is a drawing showing the UV-vis absorbance spectra for the composite structure of Example 1, the ZnO nanoparticles of Comparative Example 1, and the TiO2 nanoparticles of Comparative Example 2.

[0112] The calculated band gap and maximum absorption wavelength for the composite structure of Example 1 and the ZnO and TiO2 nanoparticles of Comparative Examples 1 and 2 are summarized in Table 1 below.

[0113] Example 1 (composite structure) Comparative Example 1 (ZnO nanoparticles) Comparative Example 2 (TiO2 nanoparticles) Band gap 4.33 eV 3.34 eV 3.23 eV Maximum absorption wavelength 302 nm 371 nm 317 nm

[0114] Referring to Fig. 7, it was confirmed that the composite structure of Example 1 had increased absorbance compared to ZnO and TiO2 nanoparticles. In addition, the red shift of the band gap of the composite structure (compared to ZnO and TiO2 nanoparticles) is correlated with the coexistence of ZnO and TiO2 nanoparticles in a single microsphere. As the carrier concentration increases, the Fermi level position shifts to the conduction band, and as a result, the Burstein-Moss effect can lead to a wide band gap. It was confirmed that the composite structure provides excellent broadband UV protection function as can be seen from the high absorbance and wide band gap values.

[0115] (4) Confirmation of specific surface area and porosity

[0116] To investigate the surface area and porosity characteristics of the composite structure of Example 1, N2 adsorption-desorption analysis was performed. Part (a) of Fig. 8 is a diagram showing the BET (Brunauer-Emmett-Teller) isotherm for the composite structure of Example 1. Referring to part (a) of Fig. 8, the BET isotherm for the composite structure of Example 1 exhibits a hysteresis loop within the relative pressure range (P / P0), which indicates the notable porous characteristics of the composite structure. The hysteresis loop indicates the presence of capillary condensation and desorption, which are generally associated with mesoporous materials.

[0117] In addition, the pore size present in the porous shell layer was calculated using NLDFT (non-local density functional theory). Part (b) of Fig. 8 is a diagram showing the size distribution of pores present in the porous shell layer of the composite structure of Example 1. Referring to part (b) of Fig. 8, it can be confirmed that most of the pores are within the mesopore and macropore range, which is important because the mesopore and macropore of the material often contribute to increasing the surface area and improving the absorption properties.

[0118] The BET surface area of ​​the composite structure of Example 1 is 43.862 m 2 / g, indicating a significant available surface for potential interactions. The average pore diameter within the composite structure of Example 1 was measured to be 76.698 Å.

[0119] <Experimental Example 2. Evaluation of Photostability of Composite Structures>

[0120] The photostability of the materials of the examples and comparative examples was evaluated through the experiments below.

[0121] (1) Observation of peak changes before and after UV simulation

[0122] The composite structure of Example 1 and the nanoparticles of Comparative Examples 1 to 3 were each dissolved in N-methyl-2-pyrrolidone (NMP) and thoroughly stirred to improve homogeneity. Then, 3 μL aliquots were taken and placed in small glass vials without tapering so that the vials would not interfere with UV light, thereby preparing experimental sample solutions.

[0123] A UV simulation was performed for 5 hours on the sample solution in which the composite structure of Example 1 and the nanoparticles of Comparative Examples 1 to 3 were each dissolved, and UV-vis absorbance spectra were analyzed before and after the simulation. The UV simulation was performed by exposing the experimental sample solution to an AM1.5G solar simulator (Abet Technologies, Inc. 168 Old Gate Lane, Milford, Connecticut 06460) using an AM1.5G air mass filter for approximately 300 minutes.

[0124] Figure 9 is a diagram showing UV-vis absorbance spectra before and after 5 hours of UV simulation for the composite structure of Example 1, ZnO nanoparticles of Comparative Example 1, TiO2 nanoparticles of Comparative Example 2, and nanoparticle mixture of Comparative Example 3.

[0125] Referring to Fig. 9, the ZnO nanoparticles of Comparative Example 1 showed superior photostability because there was no significant change in the absorbance peak before and after UV simulation, whereas the TiO2 nanoparticles showed a significant decrease in the absorbance peak after UV simulation, confirming poor photostability. Furthermore, in the case of the mixture of ZnO nanoparticles and TiO2 nanoparticles, the absorbance increased several times more than in other cases after UV simulation, confirming poor photostability. On the other hand, in the case of the composite structure of Example 1, there was no significant change in the absorbance peak in the UVA and UVB regions before and after UV simulation, confirming excellent photostability.

[0126] Also, referring to FIG. 9, in the case of the composite structure of Example 1 in which ZnO and TiO2 nanoparticles exist as a conjugate, the conjugated ZnO and TiO2 nanoparticles serve as recombination sites for photogenerated e- / h+ pairs, so the formation of reactive oxygen species (ROS) such as H2O2 and OH is small, whereas in Comparative Example 3 in which ZnO and TiO2 nanoparticles are simply mixed, the above effect was not observed.

[0127] (2) Dye decomposition experiment

[0128] First, 100 mL of a distilled water solution containing 10 ppm methylene blue was prepared, and this solution was transferred to a round-bottom flask. Then, 20 mg of each of the composite structure of Example 1, the ZnO nanoparticles of Comparative Example 1, the TiO2 nanoparticles of Comparative Example 2, and the nanoparticle mixture of Comparative Example 3 were added to the solution. The obtained mixed solution was stirred for 30 minutes in an environment not exposed to light. Before exposure to light, 2 mL of each mixed solution was aliquoted to establish a reference concentration (C0). Then, the light source was activated to expose each mixed solution to ultraviolet light, and 2 mL was aliquoted and collected at 10-minute intervals over 100 minutes. At this time, the container containing the collected sample was wrapped with aluminum foil to prevent the influence of external light on the collected sample. Each collected sample was centrifuged to obtain a supernatant, and the UV-vis absorbance of the supernatant was measured to quantify the degree of dye decomposition.

[0129] Figure 10 is a drawing showing the decomposition performance of the composite structure of Example 1, the ZnO nanoparticles of Comparative Example 1, the TiO2 nanoparticles of Comparative Example 2, and the nanoparticle mixture of Comparative Example 3 for methylene blue.

[0130] Referring to Fig. 10, the ZnO nanoparticles of Comparative Example 1, the TiO2 nanoparticles of Comparative Example 2, and the nanoparticle mixture of Comparative Example 3 showed degradation rates of 42%, 27%, and 36%, respectively, for 100 minutes, whereas the composite structure of Example 1 showed the lowest dye degradation performance with a degradation rate of close to 4%. Through this, it was confirmed that the composite structure of Example 1 had lower photocatalytic activity than ZnO nanoparticles, TiO2 nanoparticles, and the mixture of ZnO nanoparticles and TiO2 nanoparticles, and that the formation of reactive oxygen species (ROS) due to photoactivity was reduced. This suggests that the cytotoxicity of the composite structure of Example 1 can be reduced.

[0131] <Experimental Example 3. Biocompatibility Evaluation of Composite Structures>

[0132] To confirm the cytotoxicity and biocompatibility of the composite structure of Example 1 and the nanoparticles of Comparative Example 1, the nanoparticles of Comparative Example 2, and the nanoparticle mixture of Comparative Example 3, an MTT assay was performed.

[0133] Dulbecco's Modified Eagle Medium (DMEM) medium containing the composite structure of Example 1 and the nanoparticles of Comparative Example 1, nanoparticles of Comparative Example 2, and nanoparticle mixture of Comparative Example 3 at concentrations of 1, 2, 5, and 10 μg / mL, respectively, was used as a sample, and pure DMEM medium was used as a control. 5 x 10 3 cells / cm 2 Human fibroblast cell line (HFB4) with a density of 100 μg / ml was used. Cells were cultured in sample medium using 24-well plates and then incubated at 37°C and 5% CO2 for 72 hours. Then, the sample medium was removed, and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) was added to each well, and cell viability, which can be calculated as the ratio of viable cells to total cells, was evaluated using an optical analyzer. All data points in the viability analysis were expressed as the mean ± standard deviation. Statistical analysis was performed using an unpaired Student's t test to determine the statistical significance of the difference between the means of individual sample groups.

[0134] Figure 11 is a diagram showing cell viability for DMEM medium containing the composite structure of Example 1, ZnO nanoparticles of Comparative Example 1, TiO2 nanoparticles of Comparative Example 2, and nanoparticle mixture of Comparative Example 3 at concentrations of 1, 2, 5, and 10 μg / mL, respectively.

[0135] The cell viability evaluated at a higher concentration of 10 μg / mL was about 83.2% for ZnO nanoparticles, about 95.1% for TiO2 nanoparticles, and about 93.2% for the mixture of ZnO and TiO2 nanoparticles, and surprisingly, the composite structure of Example 1 exhibited the highest cell viability (96.2%) among the tested materials. The observed pattern in cell viability clearly showed that both types of nanoparticles and their 1:1 mixture tended to show a decreasing cell viability with increasing concentration. However, the composite structure of Example 1 was confirmed to maintain a relatively high cell viability even at a concentration of 10 μg / mL.

[0136] This demonstrates the excellent biocompatibility of the composite structure of Example 1, suggesting less cytotoxicity compared to individual TiO2 and ZnO nanoparticles and their mixtures. The composite structure of Example 1 exhibits favorable biocompatibility properties, making it a valuable candidate for applications such as sunscreens and compatibility with biological systems.

[0137] Examples 2 to 3 and Comparative Examples 4 to 7. Preparation of sunscreen cream

[0138] To study the UV blocking performance of the manufactured UV blocking composite structure, a UV blocking cream was manufactured according to the COLIPA manufacturing method of the European Cosmetics Association.

[0139] A cream-type sunscreen was directly manufactured by carefully mixing each ingredient according to the composition shown in Table 2 below.

[0140] Ingredients (weight parts) Example 2 Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Fatty phase Emulsifier 5.0 5.0 5.0 5.0 5.0 5.0 Cocoa butter oil (theobroma oil) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Glyceryl Stearate 3.5 3.5 3.5 3.5 3.5 3.5 Stearic acid 2.0 2.0 2.0 2.0 2.0 2.0 Aqueous phase Water 7 1.0 7 1.0 7 1.0 7 1.0 7 1.0 7 1.0 Sorbitol 5.0 5.0 5.0 5.0 5.0 Triethanolamine 1.0 1.0 1.0 1.0 1.0 Natural α-Cresol 0.5 0.5 0.5 0.5 0.5 0.5 UV blocking substance Example 152.5 ----Comparative Example 1 5 2.5 ----Comparative Example 2 5 5 2.5 ----Comparative Example 3 5

[0141] Specifically, the fatty phase component and the aqueous phase component were heated separately to a temperature in the range of 60 to 70°C to ensure complete dissolution of each content, and then the fatty phase component was gradually added to the aqueous phase component under continuous stirring. Stirring was maintained until an emulsion was formed and the mixture was cooled to room temperature (20 to 22°C). Then, the UV-blocking compositions of Example 1 and Comparative Examples 1 to 3 were each mixed with the emulsion as shown in Table 2 above. Figure 12 is a photograph of the cream-type UV-blockers prepared in Comparative Example 7, Example 2, and Example 3.

[0142] <Experimental Example 4. Evaluation of UV Protection Index of UV Blocking Agents Including Composite Structures>

[0143] SEM images were taken for Comparative Example 7, which is a blank cream without added UV blocking material, and Example 2, which includes the composite structure of the present invention. Figure 13 is a drawing showing SEM images for Comparative Example 7 (a, b) and Example 2 (c, d).

[0144] Referring to FIG. 13, in the sunscreen of Example 2, the composite structure of the present invention was very uniformly dispersed in the cream-like matrix, with no noticeable agglomeration, indicating that a sunscreen cosmetic including the composite structure of the present invention can provide consistent and effective UV blocking function.

[0145] <Experimental Example 5. Evaluation of UV Protection Index of UV Blocking Agents Including Composite Structures>

[0146] The sun protection factor (SPF) index was calculated for the sunscreens of Example 2 and Comparative Examples 4 to 6 as follows.

[0147] Prepare a polymethyl methacrylate plate of 50 mm x 50 mm size, and apply 1.5 mg / cm of each of the UV blockers of Example 2 and Comparative Examples 4 to 6 to the plate using a coated finger. 2 was applied. For accurate results, three plates with the sample applied were prepared for each case. Then, the plates with the sample applied were exposed to ultraviolet rays using a solar simulator (An ABET technology AM 1.5 G solar simulator), and the transmittance was measured within the wavelength range of 290 to 400 nm using a spectrophotometer (UV-i Selection, Shimadzu Corporation, Japan). Then, the SPF index was calculated using the standard SPF calculation formula, Mathematical Expression 1 below.

[0148] [Mathematical Formula 1]

[0149]

[0150] (T λ is the spectral transmittance of the sample, and S λ is the solar spectral irradiance, and E λis the CIE Erythemal spectral effectiveness.)

[0151] As a reference example, the transmittance and SPF index were evaluated in the same manner as above using Eau Thermale Avene sunscreen (purchased from a retail store located in Gyeongsan-si, South Korea) labeled with an SPF index of 50+.

[0152] Figure 14 is a drawing showing the results of transmittance measurements for the UV blockers of Example 2, Comparative Examples 4 to 6, and Reference Example.

[0153] Referring to Fig. 14, the sunscreen of Example 2 showed excellent ultraviolet ray blocking performance for a wide range of ultraviolet rays including UVA and UVB, and in particular, it showed excellent ultraviolet ray blocking performance in both UVB and UVA regions compared to the sunscreen of Comparative Example 6, which simply mixed ZnO nanoparticles and TiO2 nanoparticles.

[0154] The SPF indices calculated for the sunscreens of Example 2 and Comparative Examples 4 to 6 and the sunscreen of the Reference Example are shown in Table 3 below. Referring to Table 3 below, the sunscreen of Example 2 had a significantly higher SPF indices than the sunscreens of Comparative Examples 4 to 6, indicating superior sunscreen performance. In the case of the Reference Example, the SPF indices were calculated to be 53, confirming the reliability of the experiment.

[0155] Example 2 Comparative Example 4 Comparative Example 5 Comparative Example 6 Reference Example SPF Value 6525183353

[0156] <Experimental Example 6. Evaluation of whitening phenomenon of UV blocker including composite structure> In order to evaluate the whitening phenomenon of UV blocker according to the present invention, 3 cm of hand skin of experimenters with various skin colors according to Fitzpatrick skin type classification 2In Example 2, 50 mg of the sunscreen prepared was applied using a finger, rubbed in for 1 minute, waited for 5 minutes, and then an optical photograph image was taken. As a control, the blank cream of Comparative Example 7 was used. Figure 15 is a drawing showing the results of an experiment evaluating the whitening phenomenon of the sunscreen of Example 2 on subjects with various skin colors.

[0157] Referring to Figure 15, for all subjects with various skin colors, there was no difference when the sunscreen of Example 2 was used compared to the natural skin color or the control group.

[0158] Although the present invention has been described above through limited embodiments, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

Claims

1. A composite structure comprising a hollow core; two or more porous shell layers; and a hollow layer positioned between the two or more porous shell layers; A composite structure for blocking ultraviolet rays, wherein the porous shell layer comprises a conjugate of zinc oxide (ZnO) nanoparticles and titanium dioxide (TiO2) nanoparticles.

2. In claim 1, The above composite structure is a spherical structure and has an average diameter of 0.1㎛ to 5㎛, which is a composite structure for blocking ultraviolet rays.

3. In claim 1, A composite structure for blocking ultraviolet rays, wherein the band gap of the composite structure is 4 eV or more.

4. In claim 1, A composite structure for blocking ultraviolet rays, wherein the porous shell layer includes mesopores having a pore diameter in the range of 2 nm to 50 nm and macropores having a pore diameter in the range of more than 50 nm to 1000 nm.

5. In claim 1, The above composite structure is a composite structure for blocking ultraviolet rays, which comprises a porous shell layer having two or more layers and five or fewer layers.

6. A cosmetic composition for blocking ultraviolet rays, comprising a composite structure for blocking ultraviolet rays according to claim 1.

7. In claim 6, A cosmetic composition for blocking ultraviolet rays, wherein the above-mentioned ultraviolet ray blocking complex structure is included in an amount of 0.1 to 20 wt% based on the total weight of the composition.

8. In claim 6, A cosmetic composition for sun protection having a sun protection factor (SPF) value of 60 or higher.

9. A method for manufacturing a composite structure for blocking ultraviolet rays according to claim 1, Step of preparing a porous carbon support; A step of absorbing zinc and titanium into the porous carbon support; and A method for producing a composite structure for blocking ultraviolet rays, comprising the step of calcining a porous carbon support in which zinc and titanium are absorbed to obtain the composite structure.

10. In claim 9, A method for manufacturing a composite structure for blocking ultraviolet rays, wherein the above calcination is performed at a temperature of 400°C to 600°C in an air atmosphere for 1 to 5 hours.

11. In claim 9, A method for manufacturing a composite structure for blocking ultraviolet rays, wherein the porous carbon support is carbon microspheres.

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