Long ellipsoid-shaped composite particle and cosmetic composition containing same

Abstract

The purpose of this invention is to provide a composite particle that singly blocks both ultraviolet light and infrared light at the same time, has good dispersibility and photothermal effect, and is highly safe. The present invention relates to a long ellipsoid-shaped composite particle comprising a Au nanorod, a Pt nanoparticle coating layer containing Pt nanoparticles provided on the surface of the Au nanorod, and a Au nanooutermost layer provided on the surface of the Pt nanoparticle coating layer.

Description

Spheroidal composite particles and cosmetic composition containing the same

[0001] The present invention relates to prolate ellipsoidal composite particles and cosmetic compositions containing the same.

[0002] Skin aging is caused by various factors, one of which is photoaging caused by exposure to ultraviolet light. Skin aging caused by ultraviolet light has long been known, and various ultraviolet light blocking materials have been developed. In recent years, near-infrared light has also been considered a cause of skin aging, and accordingly, infrared light blocking materials have also been developed.

[0003] For example, Patent Document 1 discloses a cosmetic composition for simultaneously blocking ultraviolet and infrared rays, which contains an ultraviolet-blocking inorganic material, an infrared-blocking inorganic material, and a dispersant. Patent Document 2 discloses a cosmetic composition containing, as an active ingredient, a composite powder comprising infrared-blocking particles and ultraviolet-blocking particles coated on one surface of the infrared-blocking particles.

[0004] Japan Special Table No. 2022-533797 Publication Japanese Special Table No. 2012-519166

[0005] The cosmetic composition for simultaneous blocking of ultraviolet and infrared rays described in Patent Document 1 contains an ultraviolet blocking material and an infrared blocking material, respectively, to simultaneously block ultraviolet light and infrared light. In such a cosmetic composition, it is necessary to adjust the content ratio of each blocking inorganic material and select the type of dispersant. Furthermore, when attempting to mix the cosmetic composition with other active ingredients, the blocking materials tend to aggregate, resulting in a cloudy appearance.

[0006] Furthermore, in the composite powder described in Patent Document 2, titanium oxide (titanium dioxide) is used for the ultraviolet-blocking particles and infrared-blocking particles, but titanium oxide is classified as a group that may be carcinogenic to humans in the carcinogenicity classification established by the International Agency for Research on Cancer (IARC) (also abbreviated as IARC carcinogenicity classification), and there are safety concerns.

[0007] Therefore, an object of the present invention is to provide a composite particle that simultaneously blocks both ultraviolet light and infrared light with a single particle, has good dispersibility and photothermal effect, and is highly safe.

[0008] As a result of extensive research, the present inventors have discovered that the above-mentioned problems can be solved by using prolate ellipsoidal composite particles (hereinafter also abbreviated as "Au / Pt / Au prolate ellipsoidal nanoparticles") comprising Au nanorods, a Pt nanoparticle coating layer containing Pt nanoparticles provided on the surface of the Au nanorods, and an Au nanooutermost layer provided on the surface of the Pt nanoparticle coating layer, and have completed the present invention.

[0009] That is, the present invention is as follows: 1. A prolate ellipsoidal composite particle comprising an Au nanorod, a Pt nanoparticle coating layer containing Pt nanoparticles provided on the surface of the Au nanorod, and an Au nano outermost layer provided on the surface of the Pt nanoparticle coating layer. 2. The prolate ellipsoidal composite particle according to 1 above, which has absorption maxima simultaneously in the wavelength range of 200 nm to 400 nm and in the wavelength range of 700 nm or more. 3. The prolate ellipsoidal composite particle according to 2 above, which further has absorption maxima in the wavelength range of 500 nm to 700 nm. 4. The prolate ellipsoidal composite particle according to 1 above, which has a major axis of 100 nm to 1000 nm and a minor axis of 50 nm to 300 nm. 5. The prolate ellipsoidal composite particle according to 1 above, wherein the Au nanorod has a minor axis diameter of 5 nm to 20 nm and a major axis diameter of 15 nm to 200 nm. 6. 6. The prolate spheroidal composite particle according to 1 above, wherein the Au nanorods have an aspect ratio of 3 or more. 7. The prolate spheroidal composite particle according to 1 above, wherein the Pt nanoparticles have an aspect ratio of 1 to 2. 8. The prolate spheroidal composite particle according to 1 above, wherein the Pt nanoparticle coating layer has a thickness of 1 nm to 100 nm. 9. The prolate spheroidal composite particle according to 1 above, wherein the Au nano outermost layer has a thickness of 1 nm to 200 nm. 10. A cosmetic composition containing the prolate spheroidal composite particle according to any one of 1 to 9 above.

[0010] The composite particles of the present disclosure use a single particle rather than multiple types of particles to simultaneously block both ultraviolet light and infrared light, which results in good dispersibility and can be easily mixed with other cosmetic ingredients.

[0011] Furthermore, in the composite particles of the present disclosure, the Pt nanoparticle coating layer, which is an intermediate layer, is coated on the outside with an Au nano outermost layer, so that even when used in cosmetics, etc., the Pt is prevented from coming into direct contact with the skin and does not induce inflammatory reactions such as allergies. Furthermore, the Au in the outermost layer of the composite particles of the present disclosure has a low ionization tendency and is unlikely to release metal ions that cause inflammatory reactions such as allergies, so that from this perspective as well, the inflammatory reactions are unlikely to occur.

[0012] Furthermore, in the composite particles of the present disclosure, the rod-shaped Au nanoparticles (Au nanorods) serving as the core have a photothermal effect, absorbing light energy and generating heat. The Au nanorods are coated with an outermost Au nanolayer via a Pt nanoparticle coating layer, thereby increasing their volume compared to the Au nanorods. This increases the scattering and absorption intensity depending on the particle volume, further enhancing the photothermal effect. This leads to anti-aging effects, such as destroying melanin-producing cells (melanocytes) that cause age spots, promoting skin cell turnover, and suppressing the occurrence of age spots. Furthermore, the composite particles of the present disclosure use Au and Pt, which are not classified as carcinogenic by the IARC, and therefore can be used as highly safe cosmetic materials.

[0013] FIG. 1 is a schematic diagram of a cross section of a prolate ellipsoidal composite particle according to one embodiment of the present invention. FIG. 2 is a diagram showing the results of electron microscopy of an example of an Au nanorod. FIG. 3 is a diagram showing the results of electron microscopy of an example of a Pt / Au nanorod. FIG. 4 is a diagram showing the results of electron microscopy of a prolate ellipsoidal composite particle (Au / Pt / Au prolate ellipsoidal nanoparticle) according to one embodiment of the present invention. FIG. 5 is a schematic diagram showing the shape of a prolate ellipsoidal composite particle (Au / Pt / Au prolate ellipsoidal nanoparticle) according to one embodiment of the present invention. FIG. 6 is a diagram showing the extinction spectrum of Example 1 (Au nanorod). FIG. 7 is a diagram showing the extinction spectrum of Example 2 (Pt / Au nanorod). FIG. 8 is a diagram showing the extinction spectrum of Example 3 (Pt / Au nanorod). FIG. 9 is a diagram showing the extinction spectrum of Example 4 (Au / Pt / Au prolate ellipsoidal nanoparticle). FIG. 10 is a diagram showing the extinction spectrum of Example 5 (Au / Pt / Au prolate ellipsoidal nanoparticle). Figure 11 shows the extinction spectrum of Example 6 (Au / Pt / Au prolate ellipsoidal nanoparticles). Figure 12 shows the results of evaluating the thermal properties of nanoparticles on a substrate. Figure 13A shows the results of evaluating the photothermal effect of nanoparticles in a simulated cosmetic. Figure 13B shows the results of evaluating the photothermal effect of nanoparticles in a simulated cosmetic.

[0014] The present invention will be described in detail below based on the embodiments, but the present invention is not limited to the following embodiments and can be implemented in any modified form within the scope of the gist of the present invention.

[0015] In this specification, the use of "to" to indicate a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0016] In this specification, "blocking light" does not necessarily mean blocking 100% of the light, but also means blocking a certain percentage of the light that is less than 100%.

[0017] [Prolate ellipsoidal composite particle] The prolate ellipsoidal composite particle of this embodiment (hereinafter also referred to as the present composite particle) is characterized by including an Au nanorod, a Pt nanoparticle coating layer containing Pt nanoparticles provided on the surface of the Au nanorod, and an Au nano outermost layer provided on the surface of the Pt nanoparticle coating layer.

[0018] The composite particle has an oblong ellipsoidal shape. FIG. 5 is a schematic diagram showing the shape of an oblong ellipsoidal composite particle (Au / Pt / Au oblong ellipsoidal nanoparticle) 50 according to one embodiment of the present invention. In this specification, "oblong ellipsoidal" refers to a curved surface that extends symmetrically along a central axis in three-dimensional space, the cross section of which is elliptical and has a major axis and a minor axis. Depending on the ratio of the major axis to the minor axis, the oblong ellipsoidal shape can take on a more elongated or spherical shape. Specifically, as shown in FIG. 5, the oblong ellipsoidal shape can be defined by the ratio of the lengths in the two axial directions, that is, the diameter of the major axis 51 and the diameter of the minor axis 52. In addition, the oblong ellipsoid has a radius of curvature.

[0019] The major axis of the present composite particles is preferably 100 nm or more, more preferably 125 nm or more, and even more preferably 150 nm or more, and is preferably 1000 nm or less, more preferably 500 nm or less, and even more preferably 300 nm or less. When the major axis of the present composite particles is 100 nm or more, the composite particles can be prevented from penetrating into the dermis, and when it is 1000 nm or less, the dispersibility of the particles can be sufficiently maintained.

[0020] The major axis of the composite particle is determined by measuring the major axis dimensions of rectangles circumscribing 50 composite particles of the present embodiment randomly selected from the TEM image and averaging the measurements.

[0021] The minor axis of the present composite particles is preferably 50 nm or more, more preferably 75 nm or more, even more preferably 100 nm or more, and is preferably 300 nm or less, more preferably 250 nm or less, and even more preferably 200 nm or less. When the minor axis of the present composite particles is 50 nm or more, the Pt has a structure in which it is sufficiently coated with Au, and when it is 300 nm or less, the composite particles do not aggregate and can maintain sufficient dispersibility.

[0022] The minor axis of the composite particle is determined by measuring the minor axis dimensions of rectangles circumscribing 50 composite particles of the present embodiment randomly selected from the TEM image and averaging the measurements.

[0023] The present composite particles preferably have simultaneous absorption maxima in the wavelength range of 200 nm to 400 nm and in the wavelength range of 700 nm or more when dispersed in a solution. This allows them to simultaneously block ultraviolet light and infrared light. In the present composite particles, the absorption maxima in the wavelength range of 200 nm to 400 nm are thought to be derived from Pt nanoparticles, and the absorption maxima in the wavelength range of 700 nm or more are thought to be derived from the major axis of the prolate ellipsoid.

[0024] The composite particles preferably also have an absorption maximum in the wavelength range of 500 to 700 nm when dispersed in a solution. In the composite particles, the absorption maximum in the wavelength range of 500 to 700 nm is thought to be derived from the minor axis of the prolate ellipsoid.

[0025] As used herein, the term "absorption maximum" refers to the change in extinction from an increase to a decrease at a certain wavelength in the extinction spectrum of the combined absorption and scattering components of the composite particle. The presence or absence of an absorption maximum can be analyzed by the method described in the Examples.

[0026] A schematic diagram of the present composite particle is shown in Figure 1. As shown in Figure 1, the present composite particle 10 has a Pt nanoparticle coating layer 12 containing Pt nanoparticles provided on the surface of an Au nanorod 11, and an Au nano outermost layer 13 provided on the surface of the Pt nanoparticle coating layer 12. Each element will be described in detail below.

[0027] (Au Nanorods) The present composite particles contain Au nanorods. In this specification, "Au nanorods" refers to rod-shaped Au nanoparticles. In this specification, "rod-like" refers to a one-dimensional shape, typically a rod-like shape whose length is longer than its diameter. An example of a rod-like shape is a cylindrical shape. Figure 2 is a microscopic image of an example of an Au nanorod.

[0028] The Au nanorods in this embodiment preferably have an aspect ratio of at least 3. In this specification, the "aspect ratio of the Au nanorods" refers to the ratio of the long axis to the short axis of the particle [long axis / short axis].

[0029] The Au nanorods can sufficiently absorb infrared light when their aspect ratio is 3 or greater. The aspect ratio of the Au nanorods is preferably 3 or greater, more preferably 4 or greater, even more preferably 5 or greater, particularly preferably 6 or greater, and is, for example, 10 or less.

[0030] The "nano" in Au nanorods means that both the major and minor axes of the particles are on the order of nanometers, that is, 1 nm or more and less than 1 μm (less than 1000 nm).

[0031] The major axis of the Au nanorod is preferably 15 nm or more, more preferably 50 nm or more, even more preferably 100 nm or more, and is preferably 200 nm or less, more preferably 180 nm or less, and even more preferably 150 nm or less. By ensuring that the major axis diameter of the Au nanorod is 15 nm or more and 200 nm or less, the size required for the major axis of the prolate ellipsoid described below can be ensured in the composite particle.

[0032] The minor axis of the Au nanorod is preferably 5 nm or more, more preferably 10 nm or more, and is preferably 20 nm or less. When the minor axis of the Au nanorod is 5 nm or more and 20 nm or less, the size required for the minor axis of the oblong ellipsoid can be ensured.

[0033] The long and short axes of the Au nanorods were determined by measuring the long and short axes of 50 randomly selected particles from a transmission electron microscope (TEM) image and averaging the measurements. Specifically, the long axis of the Au nanorod was determined as the long axis of the rectangle circumscribing the TEM image of the particle, and the short axis of the circumscribing rectangle was determined as the short axis. Each of these measurements was taken for 50 particles, and the results were averaged.

[0034] The Au nanorods may be prepared by the method described later in the section on the method for producing rod-shaped composite particles, or commercially available products may be used. Examples of commercially available products include gold nanorods, 10 nm diameter (minor axis diameter (width)), λmax, 780 nm, dispersion in H ２ O, manufactured by Sigma-Aldrich (catalog number: 716812-25ML), and the like.

[0035] Au nanorods absorb infrared light and generate heat, thereby exhibiting a photothermal effect. In particular, in the present composite particle, the core Au nanorod is coated with an outermost Au nanolayer via a Pt nanoparticle coating layer (described later), thereby increasing its volume and increasing the scattering and absorption intensities depending on the volume, thereby further enhancing the photothermal effect.

[0036] (Pt nanoparticle coating layer) In this composite particle, a Pt nanoparticle coating layer containing Pt nanoparticles is provided on the surface of the Au nanorod. Figure 3 shows the results of microscopic observation of an example of a particle in which a Pt nanoparticle coating layer containing Pt nanoparticles is provided on the surface of an Au nanorod (also referred to as a "Pt / Au nanorod"). The Pt nanoparticle coating layer has the effect of absorbing and scattering ultraviolet light.

[0037] In this specification, "Pt nanoparticles" refers to Pt particles having an average particle size on the order of nanometers, i.e., 1 nm or more and less than 1 μm (less than 1000 nm). The average particle size of Pt nanoparticles is determined by measuring the Feret diameters of 50 particles randomly selected from a TEM image and averaging them.

[0038] In this embodiment, the average particle size of the Pt nanoparticles is preferably 1 nm to 60 nm. Having the average particle size of 60 nm or less can enhance the ultraviolet light absorption effect. The average particle size of the Pt nanoparticles is preferably 60 nm or less, more preferably 40 nm or less, and even more preferably 20 nm or less. Having the average particle size of the Pt nanoparticles be 1 nm or more can further enhance the photothermal effect of the Au nanorods.

[0039] In this embodiment, the Pt nanoparticles preferably have an aspect ratio of 1 to 2, and most preferably have an aspect ratio of 1, i.e., are spherical. Here, the aspect ratio of the Pt nanoparticles refers to the major axis / minor axis of the particle.

[0040] In this embodiment, the Pt nanoparticle coating layer contains Pt nanoparticles in an amount of 2.5×10 ６ Molar ~ 7 x 10 ６ It is preferable that the amount of Pt contained is 2.5 × 10 ６ The content of 7×10 mol or more has the effect of sufficiently absorbing ultraviolet light. ６ When the amount is less than 1 mole, the particles can be dispersed sufficiently without agglomeration.

[0041] The Pt nanoparticle coating layer is made of Pt nanoparticles in an amount of 3×10 per mole of composite particles. ６ It is more preferable that the content is 5×10 mol or more. ６ It is more preferable that the content is 6×10 mol or more. ６ It is more preferable that the content be less than 1 mole.

[0042] The Pt nanoparticle coating layer may contain components other than Pt nanoparticles, such as nanoparticles containing Ru, Rh, Pd, Ag, Os, and Ir. One or more of these components may be contained. The inclusion of these components provides the effect of absorbing and scattering ultraviolet light.

[0043] In this embodiment, the thickness of the Pt nanoparticle coating layer on the major axis side is preferably 1 nm to 100 nm so that the Pt nanoparticles coat the outer surfaces of the Au nanorod particles, which are the cores of the Au nanorod particles. A thickness of 1 nm or more on the major axis side of the Pt nanoparticle coating layer provides sufficient absorption of ultraviolet light, while a thickness of 100 nm or less allows the particles to be sufficiently dispersed without agglomerating.

[0044] In this composite particle, the surface of the Au nanorod is not completely covered with Pt nanoparticles without any gaps, but rather there are small gaps as shown in Figure 1. Therefore, the "thickness of the Pt nanoparticle coating layer on the major axis side" refers to the average thickness including the gaps.

[0045] In this embodiment, the thickness of the Pt nanoparticle coating layer on the major axis side is more preferably 5 nm or more, even more preferably 10 nm or more, and more preferably 90 nm or less, even more preferably 80 nm or less.

[0046] The thickness of the major axis of the Pt nanoparticle coating layer was calculated by subtracting the average major axis of the core Au nanorod from the average major axis of 50 particles (Pt / Au nanorods) randomly selected from the TEM image, each having a Pt nanoparticle coating layer on the surface. The result was divided by 2.

[0047] In order to coat the outer surfaces of the Au nanorod particles, which are the cores of the Pt nanoparticles, the thickness of the Pt nanoparticle coating layer on the minor axis side is preferably 1 nm to 100 nm. A thickness of 1 nm or more on the minor axis side of the Pt nanoparticle coating layer has the effect of sufficiently absorbing ultraviolet light, while a thickness of 100 nm or less allows the particles to be sufficiently dispersed without agglomerating.

[0048] The thickness of the Pt nanoparticle coating layer on the minor axis side is more preferably 5 nm or more, even more preferably 10 nm or more, and more preferably 90 nm or less, even more preferably 80 nm or less.

[0049] The thickness of the minor axis side of the Pt nanoparticle coating layer was calculated by subtracting the average minor axis diameter (width) of the core Au nanorod from the average minor axis diameter (width) of 50 particles (Pt / Au nanorods) with a Pt nanoparticle coating layer on the surface of the Au nanorods randomly selected from the TEM image, and dividing the result by 2.

[0050] (Au nano-outermost layer) In the present composite particle, an Au nano-outermost layer is provided on the surface of the Pt nanoparticle coating layer. In this specification, the "Au nano-outermost layer" refers to an Au film having a thickness on the order of nanometers, i.e., 1 nm or more but less than 1 μm (less than 1000 nm).

[0051] Figure 4 shows the results of microscopic observation of an example of a composite particle (Au / Pt / Au prolate ellipsoidal nanoparticle) in which a Pt nanoparticle coating layer containing Pt nanoparticles is provided on the surface of an Au nanorod core, and an Au nanoouter layer is provided on the surface of the Pt nanoparticle coating layer.

[0052] The present composite particles have an Au nano-outermost layer, so the Pt nanoparticle coating layer is not exposed on the surface of the composite particles. This prevents Pt from coming into direct contact with the skin when the present composite particles are used in cosmetics, etc., and can suppress the induction of inflammatory reactions such as allergies. Furthermore, the Au in the outermost layer of the present composite particles has a low ionization tendency and is less likely to release metal ions that cause inflammatory reactions such as allergies, making them less likely to cause inflammatory reactions from this perspective as well.

[0053] In this embodiment, the Au nano-outermost layer contains Au in an amount of 5×10 ６ ~400 x 10 ６ It is preferable that the amount of Au contained is 5×10 moles per mole of the composite particles. ６ By containing more than 400 × 10 moles of Au, Pt is coated and absorbs infrared light. ６ By containing the compound in an amount of less than 1 mole, the composite particles do not become spherical and infrared absorption can be maintained.

[0054] In this embodiment, the Au nano-outermost layer contains Au in an amount of 10×10 ６ It is more preferable that the content is 50×10 moles or more. ６ It is more preferable that the content is 300×10 mol or more. ６ It is more preferable that the content is 200×10 moles or less. ６ It is more preferable that the content be less than 1 mole.

[0055] In this embodiment, the thickness of the Au nano-outermost layer is preferably 1 nm to 200 nm. When the Au nano-outermost layer is 1 nm or more, it can cover the Pt nanoparticle coating layer, and when it is 200 nm or less, the composite particles do not become spherical and infrared absorption can be maintained.

[0056] The thickness of the Au nano-outermost layer is more preferably 5 nm or more, even more preferably 10 nm or more, and is more preferably 180 nm or less, even more preferably 150 nm or less.

[0057] The thickness of the outermost Au nanolayer was calculated by subtracting the average values ​​of the major and minor axes of the Pt / Au nanorods from the average values ​​of the major and minor axes of 50 composite particles (Au / Pt / Au prolate ellipsoidal nanoparticles) randomly selected from a transmission electron microscope (TEM) image, and dividing the result by 2.

[0058] [Method for Producing Prolate Spheroidal Composite Particles] One embodiment of the method for producing the composite particles preferably includes, for example, the following steps (1) to (3) in order: (1) a step of producing Au nanorods, (2) a step of providing a Pt nanoparticle coating layer on the surface of the Au nanorods produced in step (1) to produce Pt / Au nanorods, and (3) a step of providing an Au nano outermost layer on the surface of the Pt / Au nanorods produced in step (2) to produce Au / Pt / Au prolate spheroidal nanoparticles. Each step is described below.

[0059] (1) Step of Producing Au Nanorods Step (1) is a step of producing Au nanorods by reducing a gold source with a reducing agent in the presence of a protective agent using Au nanoclusters as nuclei. The Au clusters to be used as nuclei are prepared, for example, by dissolving HAuCl in a CTAB solution. ４ solution, NaBH ４ The mixture is stirred and aged at room temperature for 1 hour or more to obtain the desired product.

[0060] As used herein, "Au nanoclusters" refer to minute particles composed of gold atoms, typically having a diameter of several nanometers or less. Examples of the gold source include chloroauric acid, chloroaurate, potassium gold cyanide, and gold bromide. Examples of the reducing agent include inorganic compounds such as sodium borohydride and hydrazine, and organic acids or salts thereof such as hydroquinone, ascorbic acid, and citric acid.

[0061] Examples of the protective agent include surfactants such as hexadecyltrimethylammonium bromide and polyoxyethylene (20) sorbitan monolaurate, water-soluble polymers such as gelatin and BSA, and organic acid compounds such as citric acid.

[0062] The reduction conditions include, for example, standing or shaking preferably at 60° C. for 1 hour, or standing or shaking preferably at room temperature, preferably overnight.

[0063] (2) A step of providing a Pt nanoparticle coating layer on the surface of the Au nanorods prepared in step (1) to prepare Pt / Au nanorods. Step (2) is a step of reducing a platinum source with a reducing agent in the presence of a protective agent, using the Au nanorods prepared in step (1) as nuclei to prepare Pt / Au nanorods, which are particles having a Pt nanoparticle coating layer on the surface of the Au nanorods.

[0064] Examples of the platinum source include potassium chloroplatinate, platinum bromide, tetraammine platinum, etc. The protecting agent and the reduction conditions are the same as those in step (1).

[0065] (3) A step of forming an outermost Au nanolayer on the surface of the Pt / Au nanorods prepared in step (2) to produce Au / Pt / Au prolate ellipsoidal nanoparticles. Step (3) is a step of reducing a gold source with a reducing agent in the presence of a protective agent using the Pt / Au nanorods prepared in step (2) as cores to obtain Au / Pt / Au prolate ellipsoidal nanoparticles, which are the composite particles. The gold source, protective agent, and reduction conditions are the same as those in step (1).

[0066] [Cosmetic Composition] A cosmetic composition according to one embodiment of the present invention (hereinafter also referred to as the present cosmetic composition) contains the present composite particles described above.

[0067] The present cosmetic composition preferably contains 0.01 to 10% by mass of the present composite particles. When the present cosmetic composition contains 0.01% by mass or more of the present composite particles, it has the effect of simultaneously blocking ultraviolet light and infrared light. Furthermore, when the present cosmetic composition contains 10% by mass or less of the present composite particles, the particles do not aggregate and the cosmetic composition has good dispersibility.

[0068] The present cosmetic composition preferably contains the present composite particles in an amount of 0.05% by mass or more, even more preferably 0.07% by mass or more, and more preferably 5% by mass or less, even more preferably 2.5% by mass or less.

[0069] The cosmetic composition can be prepared in any formulation commonly used in the art, such as a water-in-oil or oil-in-water solution, suspension, emulsion, paste, gel, cream, lotion, powder, soap, surfactant-containing cleanser, oil, sunscreen, powder foundation, emulsion foundation, wax foundation, or spray formulation. Thus, the cosmetic composition can be prepared in a variety of formulations.

[0070] In addition to the present composite particles, the present cosmetic composition may contain components commonly used in cosmetic compositions, such as general adjuvants such as antioxidants, stabilizers, solubilizers, vitamins, pigments, and fragrances, and / or carriers. Carriers that can be used for each formulation are described below.

[0071] When the cosmetic composition is in the form of a powder or spray, examples of the carrier component include lactose, talc, silica, aluminum hydroxide, calcium silicate, or polyamide powder. In particular, when the cosmetic composition is in the form of a spray, chlorofluorohydrocarbon, propane / butane, or dimethyl ether may be additionally used.

[0072] When the cosmetic composition is in the form of a solution or emulsion, examples of the carrier component include a solvent, a solubilizer, or an emulsifier. Specific examples include water, ethyl alcohol, isopropanol, ethyl carbonate, ethyl acetate, benzyl alcohol, benzyl benzoate, propylene glycol, 1,3-butyl glycol oil, aliphatic glycerol esters, polyethylene glycol, and fatty acid esters of sorbitan.

[0073] When the cosmetic composition is in the form of a suspension, examples of the carrier component include a liquid diluent such as water, ethyl alcohol, or propylene glycol, a suspending agent such as ethoxylated isostearyl alcohol, polyoxyethylene sorbitol ester, or polyoxyethylene sorbitan ester, microcrystalline cellulose, aluminum metahydroxide, bentonite, agar, or tragacanth.

[0074] When the cosmetic composition is in the form of a paste, cream, or gel, examples of the carrier component include animal oil, vegetable oil, wax, paraffin, starch, tragacanth, cellulose derivatives, polyethylene glycol, silicone, bentonite, silica, talc, and zinc oxide.

[0075] When the cosmetic composition is in the form of a surfactant-containing cleanser, examples of the carrier component include fatty alcohol sulfates, fatty alcohol ether sulfates, sulfosuccinic acid monoesters, isocyanates, imidazolium derivatives, methyl taurates, sarcosinates, fatty acid amide ether sulfates, alkylamido betaines, fatty alcohols, fatty acid glycerides, fatty acid diethanolamides, vegetable oils, lanolin derivatives, and ethoxylated glycerol fatty acid esters.

[0076] The present cosmetic composition contains the present composite particles, which are single particles, and therefore can simultaneously block both ultraviolet light and infrared light, and the particles are uniform in size, so they have good dispersibility.

[0077] Furthermore, in the present composite particles, the Pt nanoparticle coating layer, which is the intermediate layer, is coated with an Au nano-outermost layer, so that even when the particles are contained in a cosmetic composition, the Pt is prevented from coming into direct contact with the skin, thereby suppressing inflammatory reactions such as allergies. Furthermore, the Au in the outermost layer of the present composite particles has a low ionization tendency and is unlikely to release metal ions that cause inflammatory reactions such as allergies, so that the particles are also unlikely to cause inflammatory reactions from this perspective.

[0078] Furthermore, since the Au nanorods in the present composite particles absorb light energy and generate heat, the core Au nanorods are coated with the outermost Au nanolayer via a Pt nanoparticle coating layer, which further enhances the photothermal effect. Therefore, by incorporating the present composite particles into a cosmetic composition, it is possible to achieve anti-aging effects such as destroying melanin-producing cells (melanocytes) that cause age spots, promoting skin cell turnover, and suppressing the occurrence of age spots.

[0079] As described above, the present specification discloses the following: [1] A prolate ellipsoidal composite particle comprising an Au nanorod, a Pt nanoparticle coating layer containing Pt nanoparticles provided on the surface of the Au nanorod, and an Au nano-outermost layer provided on the surface of the Pt nanoparticle coating layer. [2] The prolate ellipsoidal composite particle according to [1], which has absorption maxima simultaneously in a wavelength range of 200 nm to 400 nm and a wavelength range of 700 nm or more. [3] The prolate ellipsoidal composite particle according to [2], which further has absorption maxima in a wavelength range of 500 nm to 700 nm. [4] The prolate ellipsoidal composite particle according to any one of [1] to [3], which has a major axis of 100 nm to 1,000 nm and a minor axis of 50 nm to 300 nm. [5] The prolate ellipsoidal composite particle according to any one of [1] to [4], wherein the Au nanorod has a minor axis diameter of 5 nm to 20 nm and a major axis diameter of 15 nm to 200 nm. [6] The prolate ellipsoidal composite particle according to any one of [1] to [5], wherein the Au nanorods have an aspect ratio of 3 or more. [7] The prolate ellipsoidal composite particle according to any one of [1] to [6], wherein the Pt nanoparticles have an aspect ratio of 1 to 2. [8] The prolate ellipsoidal composite particle according to any one of [1] to [7], wherein the Pt nanoparticle coating layer has a thickness of 1 nm to 100 nm. [9] The prolate ellipsoidal composite particle according to any one of [1] to [8], wherein the Au nanooutermost layer has a thickness of 1 nm to 200 nm.

[10] A cosmetic composition containing the prolate ellipsoidal composite particle according to any one of [1] to [9].

[0080] Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments disclosed in this specification and can be appropriately modified and implemented without departing from the spirit of the invention. The embodiments disclosed in this specification can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention.

[0081] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0082] Test Example 1 Materials: Hexadecyltrimethylammonium bromide (CTAB): manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Hexadecyltrimethylammonium chloride (CTAC): manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Sodium tetrahydroborate powder (NaBH ４ ): FUJIFILM Wako Pure Chemical Industries, Ltd. Hydroquinone: FUJIFILM Wako Pure Chemical Industries, Ltd. L(+)-Ascorbic acid: FUJIFILM Wako Pure Chemical Industries, Ltd. Chloroauric acid solution 30.0 mass%: Tanaka Kikinzoku Kogyo Co., Ltd. Silver nitrate crystals: Tanaka Kikinzoku Kogyo Co., Ltd. Potassium chloroplatinate 47 mass%: Tanaka Kikinzoku Kogyo Co., Ltd.

[0083] (Method) 1. Preparation of Au nanoclusters CTAB, NaBH ４ and chloroauric acid were mixed to final concentrations of 100 mM, 0.6 mM, and 0.25 mM, respectively. The mixed solution was left to stand at room temperature for 1 hour to obtain brown gold nanoclusters.

[0084] 2. Preparation of Au nanorods CTAB, hydroquinone, chloroauric acid, and silver nitrate were mixed to final concentrations of 100 mM, 3 mM, 0.5 mM, and 0.4 mM, respectively. The gold nanoclusters prepared in step 1 above were added to the mixed solution so as to be diluted 100 times and mixed. The mixed solution was left standing overnight at room temperature to obtain Au nanorods.

[0085] 3. Preparation of Pt / Au nanorods CTAC and L(+)-ascorbic acid were mixed with the Au nanorods obtained in step 2 above to a final concentration of 10 mM. Potassium hexachloroplatinate was added to this mixed solution to a final concentration of 1-60 mM. This mixed solution was left to stand at 60°C for 1 hour to obtain Au nanorods coated with a Pt nanoparticle layer (Pt / Au nanorods).

[0086] 4. Preparation of Au / Pt / Au prolate spheroidal nanoparticles CTAC and L(+)-ascorbic acid were mixed with the Pt / Au nanorods obtained in step 3 above to a final concentration of 10 mM. Chloroauric acid was added to the mixed solution to a final concentration of 10 to 1000 mM. The mixed solution was left to stand at 60°C for 1 hour to obtain Au / Pt / Au prolate spheroidal nanoparticles.

[0087] 5. Analysis Method of Each Particle (UV, Visible, and Near-Infrared Extinction Spectra) Each of the Au nanorods, Pt / Au nanorods, and Au / Pt / Au prolate ellipsoidal nanoparticles prepared above was suspended in a 1 mM CTAB solution, and UV, visible, and near-infrared extinction spectra were obtained using a Spectrophotometer V-770 (Jusco Engineering Co., Ltd.). The results are shown in Figures 6 to 11. Figures 6 to 11 show the extinction spectra of Examples 1 to 6, respectively.

[0088] (Measurement of particle size and thickness) Each particle was suspended in water, and 1 μL of the suspension was dropped onto a collodion film-attached mesh (Nissin EM Co., Ltd.), followed by vacuum drying to prepare a sample. Images of 50 or more particles of each sample were obtained using a JEM-2100PLUS electron microscope (JEOL Ltd.), and their sizes were measured using ImageJ.

[0089] The major axis diameter of each particle was determined by measuring the major axis dimensions of a rectangle circumscribing 50 particles randomly selected from the TEM image and averaging the measurements. The minor axis diameter of each particle was determined by measuring the minor axis dimensions of a rectangle circumscribing 50 particles randomly selected from the TEM image and averaging the measurements.

[0090] The long and short axes of the Au nanorods were determined by measuring the long axis dimension of the rectangle circumscribing the TEM image of the particle, and the short axis dimension of the circumscribing rectangle, respectively, for 50 particles and averaging the measurements.

[0091] The thickness of the Pt nanoparticle coating layer on the major axis side was calculated by subtracting the average value of the major axis of the core Au nanorod from the average value of the major axes of 50 Pt / Au nanorods randomly selected from the TEM image, and dividing the result by 2.

[0092] The thickness of the Pt nanoparticle coating layer on the minor axis side was calculated by subtracting the average value of the minor axis of the core Au nanorod from the average value of the minor axis of 50 Pt / Au nanorods randomly selected from the TEM image, and dividing the result by 2.

[0093] The thickness of the outermost Au nanolayer was calculated by subtracting the average major and minor axes of the Pt / Au nanorods from the average major and minor axes of 50 Au / Pt / Au prolate nanoparticles randomly selected from a transmission electron microscope (TEM) image, and dividing the result by 2.

[0094] The results are shown in Table 1. In Table 1, Examples 1 to 3 are Reference Examples, and Examples 4 to 6 are Working Examples.

[0095]

[0096] Figure 6 shows the extinction spectrum of Example 1, Figure 7 shows the extinction spectrum of Example 2, Figure 8 shows the extinction spectrum of Example 3, Figure 9 shows the extinction spectrum of Example 4, Figure 10 shows the extinction spectrum of Example 5, and Figure 11 shows the extinction spectrum of Example 6. Example 2 shows the lower limit of the Pt amount in the composite particles of the present application, and Example 3 shows the upper limit of the Pt amount in the composite particles of the present application. Furthermore, Example 4 shows the lower limit of the Au amount in the outermost Au nanolayer in the composite particles of the present application, and Example 6 shows the upper limit of the Au amount in the outermost Au nanolayer in the composite particles of the present application.

[0097] As shown in FIGS. 6 to 11 , the Au / Pt / Au prolate ellipsoidal nanoparticles of Examples 4 to 6, which are working examples, had simultaneous absorption maxima in three wavelength regions: 200 nm to 400 nm, 500 nm to 700 nm, and 700 nm or longer, and were therefore able to simultaneously block ultraviolet light, visible light, and infrared light.

[0098] (Structure Identification) The results of electron microscope observation of Au nanorods (Example 7), Pt / Au nanorods (Example 8), and Au / Pt / Au prolate ellipsoidal nanoparticles (Example 9) are shown in Figures 2 to 4, respectively. The results of measuring the average major axis diameter and average minor axis diameter of Examples 7 to 9 are shown in Table 2. Examples 7 and 8 are reference examples, and Example 9 is an embodiment.

[0099]

[0100] Test Example 2 In this test example, Au / Pt / Au prolate ellipsoidal nanoparticles were coated on a plastic substrate using a silane coupling agent, and then the thermal properties of the Au / Pt / Au prolate ellipsoidal nanoparticles were evaluated on the substrate by measuring the temperature change due to laser irradiation.

[0101] Materials: Au / Pt / Au prolate nanoparticles, 11-mercaptoundecanoic acid (MUA) (Sigma 450561), 3-aminopropyltrimethoxysilane (APTMS) (Fujifilm Wako Pure Chemical Industries, Ltd. 323-74352), tris(hydroxymethyl)aminomethane (Nacalai Tesque 35409-45), 1N HCl (Fujifilm Wako Pure Chemical Industries, Ltd. 083-01095), polyoxyethylene (20) sorbitan monooleate (Fujifilm Wako Pure Chemical Industries, Ltd. 163-21625), 1N NaOH (Kanto Chemical Co., Ltd. 37847-79), compact plasma generator (Yamato Scientific PM100), 35mm dish for adherent cells (IWAKI 3000-035).・980nm laser (MDL-III-980-500mW FC31445) ・Radiation thermometer (Japan Sensor TMHX-CNE0500-0070E003)

[0102] (Method) 1. Coating of silane coupling agent on substrate: A 35 mm plastic dish was plasma treated for 15 minutes using a small plasma device to hydrophilize the surface of the dish. 2 mL of a 1% APTMS aqueous solution was added and allowed to stand at room temperature for 30 minutes. After standing, the dish was washed with purified water and air-dried.

[0103] 2. Protecting Agent Substitution for Au / Pt / Au Prolate Spheroidal Nanoparticles 950 μL of a dispersion containing 2.5 nM Au / Pt / Au prolate spheroidal nanoparticles was centrifuged, the supernatant removed, and then added to 950 μL of a 10 mM NaOH solution containing 1 mM 11-mercaptoundecanoic acid (MUA) to disperse the particles. This dispersion was aged at room temperature for 1 hour by shaking at 500 rpm. After aging, the dispersion was centrifuged again and the supernatant removed. Next, the nanoparticles were dispersed in a 10 mM tris(hydroxymethyl)aminomethane (Tris-HCl) solution adjusted to pH 8.5 and containing 0.1% by mass of polyoxyethylene (20) sorbitan monooleate to a particle concentration of 2.5 nM.

[0104] 3. Coating of Au / Pt / Au prolate spheroidal nanoparticles onto a substrate: 950 μL of the Au / Pt / Au prolate spheroidal nanoparticle dispersion liquid in which the protective material had been replaced in Test Example 2 (Method) 2. was placed in a plastic dish coated with a silane coupling agent in Test Example 2 (Method) 1., and the dish was shaken overnight at 500 rpm. The supernatant was removed, and the dish was washed with purified water and air-dried.

[0105] 4. Laser irradiation of substrate and temperature measurement. The center of the final plastic dish coated with Au / Pt / Au prolate nanoparticles was irradiated with a 980 nm laser (MDL-III-980-500 mW FC31445). The temperature of the irradiated area was measured using a radiation thermometer (Japan Sensor TMHX-CNE0500-0070E003). After the start of laser irradiation, the point at which the measured value stabilized was set as time 0, and the temperature change over the next 5 minutes was recorded.

[0106] The results are shown in Figure 12. In Figure 12, the solid line shows the results without Au / Pt / Au prolate spheroidal nanoparticles, and the dashed line shows the results with Au / Pt / Au prolate spheroidal nanoparticles. Figure 12 shows that the dish temperature increased with infrared irradiation in the dish containing Au / Pt / Au prolate spheroidal nanoparticles, demonstrating that the Au / Pt / Au prolate spheroidal nanoparticles of the present disclosure have a photothermal effect of absorbing light energy and generating heat.

[0107] Test Example 3: In this test example, the photothermal effect of Au / Pt / Au prolate spheroidal nanoparticles in simulated cosmetics was investigated. Specifically, Au / Pt / Au prolate spheroidal nanoparticles were added to commercially available cosmetics (sunscreen or foundation), which were then coated onto plastic substrates. The temperature change due to laser irradiation was measured to evaluate the photothermal properties of the Au / Pt / Au prolate spheroidal nanoparticles.

[0108] (Materials) Au / Pt / Au prolate ellipsoidal nanoparticles prepared in Test Example 2 (Method) 2. Commercially available cosmetics: Sunscreen (Rohto Pharmaceutical Skin Aqua Tone Up UV), Foundation (Shiseido Maquillage Dramatic Essence Liquid Ocher 10), 35 mm dish for adherent cells (IWAKI 3000-035), 980 nm laser (MDL-III-980-500 mW FC31445), Radiation thermometer (Japan Sensor TMHX-CNE0500-0070E003).

[0109] (Method) 1. Preparation of simulated cosmetics (mixing of commercial cosmetics with Au / Pt / Au prolate spheroidal particles) 90 mg of commercial cosmetics was weighed out, and 10 μL of a dispersion containing 25 nM Au / Pt / Au prolate spheroidal nanoparticles was added to it. After addition, the mixture was mixed with a medicine spoon until it was uniform.

[0110] 2. Coating onto a substrate 18 mg of the simulant cosmetic of Test Example 3 (Method) 1. or the commercially available cosmetic alone was weighed out into a 35 mm dish. The weighed simulant cosmetic or commercially available cosmetic was spread over the entire dish with a spatula.

[0111] 3. Laser irradiation of substrate and temperature measurement A 980 nm laser was irradiated onto the center of the plastic dish of Test Example 3 (Method) 2, and the temperature of the irradiated area was measured with a radiation thermometer. The time when the measured value stabilized after the start of laser irradiation was set to time 0, and the temperature change over 5 minutes from that time was measured.

[0112] The results are shown in Figures 13A and 13B. In Figure 13A, the solid line shows the results when only sunscreen was used, and the dashed line shows the results when Au / Pt / Au prolate spheroidal nanoparticles were added to the sunscreen. In Figure 13B, the solid line shows the results when only foundation was used, and the dashed line shows the results when Au / Pt / Au prolate spheroidal nanoparticles were added to the foundation. Figures 13A and 13B show that the temperature of the dish increased more with infrared irradiation when the Au / Pt / Au prolate spheroidal nanoparticles were present than when they were not present, demonstrating that the Au / Pt / Au prolate spheroidal nanoparticles of the present disclosure have a photothermal effect of absorbing light energy and generating heat, even when incorporated into cosmetics.

[0113] Test Example 4: In this test example, the optical properties of Au / Pt / Au prolate spheroidal nanoparticles in a simulated cosmetic were investigated. Specifically, Au / Pt / Au prolate spheroidal nanoparticles were added to a commercially available cosmetic, and the transmittance characteristics of the Au / Pt / Au prolate spheroidal nanoparticles were evaluated by measuring the ultraviolet and near-infrared absorbance of the resulting solution.

[0114] (Materials) Au / Pt / Au prolate ellipsoidal nanoparticle dispersion prepared in Test Example 2 (Method) 2. Commercially available cosmetics Sunscreen (Rohto Pharmaceutical Skin Aqua Tone Up UV) Foundation (Shiseido Maquillage Dramatic Essence Liquid Ocher 10) Spectrophotometer V-770 (Jasco Engineering Co., Ltd.)

[0115] (Method) 1. Mixing of commercial cosmetics with Au / Pt / Au prolate spheroidal nanoparticles 10 mg of commercial cosmetics was mixed with 990 μL of purified water to prepare a mixed solution. 10 μL of this solution was mixed with 10 μL of a dispersion containing 25 nM Au / Pt / Au prolate spheroidal nanoparticles to prepare a mixed solution.

[0116] 2. Measurement of transmittance The ultraviolet and near-infrared absorbance of the solution prepared in 1 was measured using a Spectrophotometer V-770. The transmittance was calculated from the obtained absorbance.

[0117] The results are shown in Tables 3 and 4.

[0118]

[0119]

[0120] As shown in Tables 3 and 4, the transmittance of ultraviolet and infrared rays was reduced in the presence of Au / Pt / Au prolate ellipsoidal nanoparticles compared to the absence of Au / Pt / Au prolate ellipsoidal nanoparticles. This indicates that the Au / Pt / Au prolate ellipsoidal nanoparticles of the present disclosure can effectively block ultraviolet and infrared light simultaneously even when incorporated into cosmetics.

[0121] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2024-073904) filed on April 30, 2024, the entirety of which is incorporated by reference. All references cited herein are incorporated in their entirety.

[0122] 10, 50: Prolate ellipsoidal composite particle 11: Au nanorod 12: Pt nanoparticle coating layer 13: Au nano outermost layer 51: Long axis 52: Short axis

Claims

1. A prolate ellipsoidal composite particle comprising an Au nanorod, a Pt nanoparticle coating layer containing Pt nanoparticles provided on the surface of the Au nanorod, and an Au nano outermost layer provided on the surface of the Pt nanoparticle coating layer.

2. The oblong ellipsoidal composite particle according to claim 1, which has absorption maxima simultaneously in the wavelength range of 200 nm to 400 nm and in the wavelength range of 700 nm or longer.

3. The oblong ellipsoidal composite particle according to claim 2, further having an absorption maximum in the wavelength range of 500 nm to 700 nm.

4. The oblong composite particle according to claim 1, wherein the major axis is from 100 nm to 1000 nm and the minor axis is from 50 nm to 300 nm.

5. The oblong composite particle according to claim 1, wherein the Au nanorods have a minor axis diameter of 5 nm or more and 20 nm or less and a major axis diameter of 15 nm or more and 200 nm or less.

6. The oblong ellipsoidal composite particle according to claim 1, wherein the aspect ratio of the Au nanorods is 3 or more.

7. The oblong ellipsoidal composite particles according to claim 1, wherein the aspect ratio of the Pt nanoparticles is 1 to 2.

8. The prolate ellipsoidal composite particle according to claim 1, wherein the thickness of the Pt nanoparticle coating layer is 1 nm to 100 nm.

9. The oblong ellipsoidal composite particle according to claim 1, wherein the thickness of the outermost Au nanolayer is 1 nm to 200 nm.

10. A cosmetic composition containing the prolate ellipsoidal composite particles according to any one of claims 1 to 9.

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