COSMETIC COMPOSITIONS CAPABLE OF PRODUCING LOCALIZED SURFACE PLASMONIC RESONANCE IN RESPONSE TO INDOOR AND/OR OUTDOOR LIGHTING SOURCES

Abstract

A topical skin composition and methods for its use are described. The composition can include a plurality of first plasmonic noble metal nanostructures having an aspect ratio of greater than 1 and being configured to absorb electromagnetic radiation from an artificial light source and/or from a solar radiation source to produce a first localized surface plasmon resonance (LSPR), and a plurality of second plasmonic noble metal nanostructures having an aspect ratio of greater than 1 and being configured to absorb electromagnetic radiation from a solar radiation source to produce a second LSPR.

Claims

1. A topical skin composition comprising: (a) a plurality of first plasmonic noble metal nanostructures having an aspect ratio of greater than 1 and being configured to absorb electromagnetic radiation from an artificial light source and/or from a solar radiation source to produce a first localized surface plasmon resonance (LSPR); and (b) a plurality of second plasmonic noble metal nanostructures having an aspect ratio of greater than 1 and being configured to absorb electromagnetic radiation from a solar radiation source to produce a second LSPR.

2. The topical skin composition of claim 1, wherein: the plurality of first plasmonic noble metals are configured to absorb electromagnetic radiation having a wavelength of 580 nm to 650 nm to produce the first LSPR; and the plurality of second plasmonic noble metals are configured to absorb electromagnetic radiation having a wavelength of 651 nm to 750 nm to produce the second LSPR.

3. The topical skin composition of claim 2, wherein: the plurality of first plasmonic noble metals are configured to absorb electromagnetic radiation having a wavelength of 600 nm to 630 nm to produce the first LSPR; and the plurality of second plasmonic noble metals are configured to absorb electromagnetic radiation having a wavelength of 675 to 725 to produce the second LSPR.

4. The topical skin composition of claim 2, wherein: the aspect ratio of the plurality of first plasmonic noble metal nanostructures is 1.7 to 2.5; and the aspect ratio of the plurality of second plasmonic noble metal nanostructures is 2.5 to 3.5.

5. The topical skin composition of claim 1, further comprising a plurality of third plasmonic noble metal nanostructures having an aspect ratio of greater than 1 and being configured to absorb electromagnetic radiation having a wavelength of 751 to 900 nm to produce a third LSPR.

6. The topical skin composition of claim 5, wherein the aspect ratio of the plurality of third plasmonic noble metal nanostructures is 3.5 to 5.0.

7. The topical skin composition of claim 1, further comprising: a plurality of fourth plasmonic noble metal nanostructures having an aspect ratio of greater than 1 and being configured to absorb electromagnetic radiation having a wavelength of 901 to 1150 nm, preferably about 1000 nm to 1100 nm, to produce a fourth LSPR, wherein the aspect ratio of the plurality of fourth plasmonic noble metal nanostructures is 5.0 to 7.5; plurality of fifth plasmonic noble metal nanostructures having an aspect ratio of greater than 1 and being configured to absorb electromagnetic radiation having a wavelength of 1151 to 1400 nm, to produce a fifth LSPR, wherein the aspect ratio of the plurality of fifth plasmonic noble metal nanostructures is 7.5 to 10.2; a plurality of sixth plasmonic noble metal nanostructures having an aspect ratio of greater than 1 and being configured to absorb electromagnetic radiation having a wavelength of 1401 to 1800 nm to produce a sixth LSPR, wherein the aspect ratio of the plurality of sixth plasmonic noble metal nanostructures is 10.2 to 14.5; or combinations thereof.

8. The topical skin composition of claim 1, wherein the plurality of first plasmonic noble metal nanostructures are configured to absorb electromagnetic radiation from an artificial light source selected from a fluorescent light source, a light emitting diode light source, or a laser source, or a mixture thereof.

9. The topical skin composition of claim 1, wherein the solar radiation source is natural sunlight, a solar simulator, an incandescent light source, or halogen light source.

10. The topical skin composition of claim 1, wherein the plurality of first, second, third, fourth, fifth, and/or sixth plasmonic noble metal nanostructures are gold, silver, or platinum plasmonic nanostructures, or alloys thereof, preferably plasmonic gold nanostructures.

11. The topical skin composition of claim 1, wherein the plurality of first, second, third, fourth, fifth, and sixth plasmonic noble metal nanostructures are nanorods.

12. The topical skin composition of claim 11, wherein the first, second, third, fourth, fifth and/or sixth LSPR(s) are produced along the longitudinal axis of the first, second, third, fourth, fifth and/or sixth plasmonic noble metal nanostructures, respectively.

13. The topical skin composition of claim 1, wherein the composition is an emulsion, preferably an oil-in-water emulsion.

14. The topical skin composition of claim 1, wherein the composition is a cream, a lotion, a solution, a gel, a suspension, or an anhydrous powder or stick.

15. The topical skin composition of claim 1, wherein the composition comprises 0.0001 wt. % to 20 wt. %, of the first, second, third, fourth, fifth and/or sixth plurality of plasmonic noble metal nanostructures, based on the total weight of the composition.

16. A method comprising topically applying the composition of claim 1 to skin.

17. The method of claim 16, wherein the composition is subjected to electromagnetic radiation from: an artificial light source and/or from a solar radiation source and the plurality of first plasmonic noble metal nanostructures produces a first LSPR; and/or a solar radiation source and the plurality of second plasmonic noble metal nanostructures produces a second LSPR, the plurality of third plasmonic noble metal nanostructures produces a third LSPR, the plurality of fourth plasmonic noble metal nanostructures produces a fourth LSPR, the plurality of fifth plasmonic noble metal nanostructures produces a fifth LSPR, and/or the plurality of sixth plasmonic noble metal nanostructures produces a sixth LSPR, wherein the produced first and/or second and/or third LSPR(s) reduce(s) free radicals and/or oxidants.

18. The method of claim 16, wherein: the aspect ratio of the plurality of first plasmonic noble metal nanostructures is 1.7 to 2.5 and wherein the nanostructures absorb electromagnetic radiation having a wavelength of 580 nm to 650 nm to produce the first LSPR; and/or the aspect ratio of the plurality of second plasmonic noble metal nanostructures is 2.5 to 3.5 and wherein the nanostructures absorb electromagnetic radiation having a wavelength of 651 nm to 750 nm to produce the second LSPR; the aspect ratio of the plurality of third plasmonic noble metal nanostructures is 3.5 to 5.0 and wherein the nanostructures absorb electromagnetic radiation having a wavelength of 751 nm to 900 nm to produce the third LSPR; the aspect ratio of the plurality of fourth plasmonic noble metal nanostructures is 5.0 to 7.5 and wherein the nanostructures absorb electromagnetic radiation having a wavelength of 901 nm to 1150 nm to produce the fourth LSPR; the aspect ratio of the plurality of fifth plasmonic noble metal nanostructures is 7.5 to 10.2, and wherein the nanostructures absorb electromagnetic radiation having a wavelength of 1151 nm to 1400 nm to produce the fifth LSPR; and/or the aspect ratio of the plurality of sixth plasmonic noble metal nanostructures is 10.2 to 14.5, and wherein the nanostructures absorb electromagnetic radiation having a wavelength of 1401 nm to 1800 nm to produce the sixth LSPR.

19. The method of claim 16, wherein the artificial lighting source is a fluorescent light source, a light emitting diode light source, or a laser source, or a mixture thereof.

20. The method of claim 16, wherein the solar radiation source is natural sunlight, a solar simulator, an incandescent light source, or a halogen light source.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed description and upon reference to the accompanying drawings.

[0030] FIG. 1 provides a comparison of spherically shaped nanoparticles and nanorods (absorbance was normalized to that of 30 nm for nanoparticles at 400 nm). NPS is nanoparticles and NRS is nanorods.

[0031] FIG. 2 depicts a light spectra for commercial LED lights sources and a fluorescent light source.

[0032] FIG. 3 depicts graphs of relative light intensity versus wavelength for different commercial light sources.

[0033] FIG. 4 depicts the ASTM G173-03 reference solar spectrum.

[0034] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings. The drawings may not be to scale.

DETAILED DESCRIPTION OF THE INVENTION

[0035] The topical skin formulations of the present invention can include a plurality of first, second, third, or more plasmonic noble metal nanostructures. Each plurality of nanostructures can have an aspect ratio of greater than one (1), which allows for the tuning of the nanoparticles to have desired plasmonic peaks (plasmonic peak and LSPR peak can be used interchangeably throughout this specification). By having blends of different plasmonic nanostructures (and therefore blends of different plasmonic peaks) in any given topical skin formulation, the resulting formulation can continue to produce LSPR(s) in response to different lighting conditions. Thus, the topical skin formulations of the present invention can be specifically tuned to match desired lighting conditions. This can allow for compositions of the present invention to produce LSPRs in response to specific lighting sources (e.g., artificial light sources and/or natural lighting sources such as sunlight). A technical advantage of this when compared with known cosmetic compositions is that the composition can continue to produce therapeutically effective amounts of LSPR irrespective of whether the lighting conditions change (e.g., change from LED lighting to incandescent light or change from artificial lighting to natural sunlight and vice versa.). In one preferred embodiment, it has been discovered that the creation of plasmonic nanostructures having a plasmonic peak of 600 nm to 630 nm can be used for both indoor lighting sources (LED, incandescent, fluorescent, laser, etc.) and outdoor lighting sources (e.g., natural sunlight or light from a solar simulator) to produce a desired LSPR. Even further, it has also been discovered that nanostructures having a plasmonic peak of 651 nm to 750 nm, preferably 675 nm to 725 nm, or more preferably about 700 nm, work well in response to outdoor lighting conditions (e.g., natural sunlight, incandescent light, halogen lights or solar simulator). Still further, it has been discovered that nanostructures having a plasmonic peak of 751 nm to 900 nm, preferably 850 nm, also works well in outdoor lighting conditions. By including various blends/combinations of such nanostructures in any given topical skin composition, the composition can continue to produce a robust LSPR response under changing lighting conditions (e.g., moving from outdoors to indoors or indoors to outdoors or a change from LED light to incandescent light, etc.).

[0036] These and other non-limiting aspects of the present invention are discussed in further detail in the following sections with reference to the Figures.

A. Plasmonic Noble Metal Nanostructures

[0037] The oscillations of electrons in the conduction band of noble metal nanostructures can induce oscillating electric fields on the surface of the nanostructures. These oscillating electric fields produce a LSPR. The LSPR is triggered when a nanostructure absorbs a sufficient amount of light having a given wavelength, thereby resulting in the oscillation of the electrons. For any given nanostructure capable of producing a LSPR, there is a corresponding light absorbance spectrum that triggers the LSPR response. This absorbance spectrum is generally referred to as the plasmonic or LSPR peak.

[0038] Plasmonic noble metal nanostructures can be designed or tuned to have a desired plasmonic peak. In particular, this tuning can occur by modifying the shape of the nanostructure to have a particular aspect ratio. Aspect ratio refers to the length divided by the width of a nanostructure. A length and a width of a given nanostructure can each be a straight-line distance measured between outermost surfaces of the nanostructure, where the length is the largest such distance and the width is perpendicular to the length. FIG. 1 illustrates the tuning concept guided by modifying the aspect ratio of a plasmonic gold nanostructure. In particular, the plasmonic peaks of gold spherical nanoparticles (NPS) are compared to gold rod-shaped nanostructures (NRS). The NPS, which has an aspect ratio of about 1, has a plasmonic peak of around 520 nm. By comparison, the peaks shift towards longer wavelengths (from higher to lower energy wavelengths or from blue light to red light and infrared light) when their respective aspect ratios are increased. For instance, gold NRS having an aspect ratio of 2.8 have a plasmonic peak of about 670 nm. Gold NRS having an aspect ratio of 3.71 have a plasmonic peak of about 760 nm. Gold NRS having an aspect ratio of 4.5 have a plasmonic peak of about 850 nm. Therefore, by changing the dimensions of the nanostructures, the nanostructures can be tuned to produce LSPRs at selected wavelengths having sufficient light intensities. Thus, combinations/blends/mixtures of plasmonic nanostructures can be created in the context of the present invention that can be used to produce therapeutically effective LSPRs in response to particular lighting conditions. By way of example only, a combination of plasmonic noble metal nanostructures can include: (1) a plurality of a first set of nanostructures that produce a first LSPR in response to any given artificial light source (e.g., light emitting diodes, fluorescent lights, lasers, etc.) or solar radiation source (natural sunlight, incandescent lights, halogen lights, or a solar simulator); and (2) a plurality of a second set of nanostructures that the produce a second LSPR in response to any given artificial light source or a solar radiation source. Combinations can include three, four, five, six, seven, or more sets of nanostructures each tuned to a given light wavelength and intensity, and hence, a given light source. This allows for the creation of combinations that can produce LSPRs in response to any combination of light sources. For example, a combination of plasmonic nanostructures can produce LSPRs in response to a light emitting diode (LED) source and solar radiation. Another combination of plasmonic nanostructures can produce LSPRs in response to a LED source and a fluorescent light source. A further combination of plasmonic nanostructures can produce LSPRs in response to a LED source and an incandescent light source. Another combination of plasmonic nanostructure can produce LSPRs in response to a LED source and a laser source or a halogen source. Yet another combination of plasmonic nanostructures can produce LSPRs in response to a LED source, solar radiation, and a fluorescent light source. Still further, another combination of plasmonic nanostructures can produce LSPRs in response to a LED source, a fluorescent light source, and an incandescent light source. Another combination of plasmonic nanostructures can produce LSPRs in response to a LED source, solar radiation, a fluorescent light source, and an incandescent light source. In the context of the present invention, any combination of nanoparticles can be created such that the resulting combination produces LSPRs in response to any desired lighting source. Further, and as discussed below and throughout this specification, these combinations can be incorporated into topical skin compositions, thereby resulting in compositions can produce effective LSPRs in response to changing lighting conditions (e.g., a user having the composition on skin moves from indoors to outdoors, or vice versa, or changes artificial lighting sources (e.g., LED to incandescent, or vice versa)).

[0039] The plasmonic noble metal nanostructures of the present invention can typically have an aspect ratio of greater than 1. The shapes of such nanostructures can be ovals, rectangles, rods, pyramids, random, etc., with rod-shaped nanostructures being preferred (i.e., nanorods, which can also be referred to as nanowires). The general shape of a nanorod is that it has an aspect ratio of greater than 1 and has a generally stick-like or dowel-like shape. Nanorods can be generally straight in the longitudinal direction but can also have some curvature or bend in the longitudinal direction. The aspect ratios of the nanostructures of the present invention can be tuned or designed to be greater than 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9., 3., 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4,9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11.0, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12.0, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 13.0, 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 13.9, 14.0, 14.1, 14.2, 14.3, 14.4, 14.5, 14.6, 14.7, 14.8, 14,9, 15.0 or more, or any range therein. These various aspect ratios can be used to ensure that the nanostructures respond to desired or targeted light sources. By way of example, and with reference to FIG. 2, the light spectrum and relative intensity of commercial LED lights (Philips A19 60W 2700K and Cree TW T8 2700K) and a fluorescent light source are provided. The primary intensity peaks of the aforementioned commercially available LED lights are around 600 nm to 630 nm. The fluorescent light has an intensity peak of around 620 nm. It has been discovered that an aspect ratio of about 1.7 to about 2.5, preferably about 1.9 to about 2.3, can be used to produce a plasmonic noble metal nanostructure that exhibits a plasmonic peak within this 600 nm to 630 nm range, thereby making such a nanostructure tuned to produce an LSPR in response to such lighting sources. FIG. 3 displays general light intensity versus wavelength relationships for different lights resources. This can be used as guidance in illustrating how to selectively tune a nanostructure of the present invention to a given light source. Further, and with reference to FIG. 4, which concerns the natural light spectrum, a nanostructure having a plasmonic peak of 600 nm to 630 nm can also be capable of producing an LSPR in response to solar radiation (e.g., natural sunlight, an incandescent light source, or a halogen light source or light from a solar simulator) Still further, it has been discovered that an aspect ratio of 2.5 to 3.5, preferably about 3.0, can be used to produce a plasmonic nanostructure having a plasmonic peak within 651 nm to 750 nm, preferably about 675 nm to 725 nm, or more preferably about 700 nm, which can be beneficial for producing an LSPR in response to natural sunlight or light produced from a solar simulator. Similarly, it has been discovered that an aspect ratio of 3.5 to 5.0, preferably about 4.5, can be used to produce a plasmonic nanostructure having a plasmonic peak within 751 nm to 900 nm, preferably about 850 nm, which can also be beneficial for producing an LSPR in response to natural sunlight or light produced from a solar simulator. Even further, is has been discovered that an aspect ratio of: 1) 5.0 to 7.5, preferably 6.0 to 7.0, can be used to produce a plasmonic nanostructure having a plasmonic peak within 901 to 1150 nm, preferably about 1000 nm to 1100 nm in response to electromagnetic radiation; 2). 7.5 to 10.2, preferably 8.0 to 9.2, can be used to produce a plasmonic nanostructure having a plasmonic peak within 1151 to 1400 nm, preferably about 1200 nm to 1300 nm in response to electromagnetic radiation; and 3) 10.2 to 14.5, preferably 11.2 to 12.5, can be used to produce a plasmonic nanostructure having a plasmonic peak within 1401 to 1800 nm, preferably about 1500 nm to 1600 nm in response to electromagnetic radiation. Therefore, use of these combinations of such nanostructures in topical skin formulations can result in a formulation that can be capable of producing LSPRs in various indoor lighting conditions and/or outdoor lighting conditions.

[0040] Plasmonic noble metal nanostructures such as nanorods can be purchased from a variety of commercial sources. For example, Sigma-Aldrich Co. LLC, St. Louis, Mo. (USA) and Nanopartz Inc., Loveland Colo. (USA), each offer gold, platinum, and palladium nanorods in different lengths.

[0041] In addition to purchasing plasmonic noble metal nanostructures, there are many techniques known to those having skill in the art for making such nanostructures. By way of example, U.S. Pat. No. 7,691,176 to Niidome et al., which is incorporated by reference, explains that conventional methods of making plasmonic metal nanorods (e.g., gold nanorods) include an electrolytic method, a chemical reduction method, or a photo-reduction method. With the electrolytic method (See, for example, Yu et al., Phys. Chem. B, 1997, 101, p. 6661) a solution containing a cationic surfactant can be electrolyzed by constant current, and gold clusters can be leached from a gold plate at the anode, thereby generating gold nanorods. The surfactant that can be used can be a quaternary ammonium salt having a structure in which four hydrophobic substituents are bonded to a nitrogen atom. Additionally, a compound (e.g., tetradodecylammonium bromide (TDAB)) in which an autonomous molecular assembly is not formed can be added to the solution. When gold nanorods are being produced, the source of the gold can be gold clusters that are leached from a gold plate at the anode. Ultrasonic waves can be radiated during electrolysis, a silver plate can be immersed in the solution, and the growth of the gold nanorods can be accelerated.

[0042] By comparison, the chemical reduction method (See, Jana et al., J. Phys. Chem. B, 2001, 105, p. 4065) can include reduction of chlorauric acid with NaBH.sub.4 to generate gold nanoparticles. These nanoparticles, which are considered seed particles, can then be grown in solution to produce nanorods. The length of the gold nanorods can be determined according to the quantitative ratio of the seed particles to the chlorauric acid added to the growth solution. With the chemical reduction method, it can be possible to generate longer gold nanorods in comparison with the above-described electrolytic method. For this chemical reduction method, two reaction baths for the preparation and reaction to grow the seed particles can be used. Chemical reduction is also known as seeded growth method can be used for preparing gold nanorods as it produces high yields of rods. Gold nanorods with desired aspect ratios can be obtained by justifying the rod growth condition, including surfactant (CTAB, for instance) and its concentration, silver ion (AgNO.sub.3 for instance) content, temperature and duration, as well as solvent used.

[0043] With respect to the photo-reduction method (See, Kim et al., Am. Chem. Soc., 2002, Vol. 124, p. 143160 chloroauric acid can be added to a solution that can be similar to the solution used in the electrolytic method. Ultraviolet irradiation can reduce the chloroauric acid. For irradiation, a low-pressure mercury lamp can be used. In the photo-reduction method, gold nanorods can be generated without producing seed particles. Further, the length of the gold nanorods can be controlled by the irradiation time, with shorter times correlating to shorter rods, and longer times correlating to longer rods.

[0044] For each production method, the desired plasmonic noble-metal or precursor material thereof (e.g., noble metal salt) can be used. In some particular embodiments of the present invention, the plasmonic noble-metal nanostructures include noble metals selected from gold, silver, palladium, platinum, or alloys thereof In preferred instances, gold or silver can be used, with gold being more preferable. Further, the produced nanostructures of the present invention can be mixed into and/or dispersed in aqueous or hydrophobic phases of any given topical skin composition and remain stable. This allows for the inclusion of the plasmonic noble metal nanostructures of the present invention in all types of topical skin compositions, including the non-limiting compositions discussed throughout the specification and directly below.

B. Topical Skin Compositions

[0045] The plasmonic noble metal nanostructures of the present invention can be incorporated into topical skin compositions of the present invention. This provides the compositions with the ability to produce LSPR(s) in response to light sources based on the plasmonic peaks of the nanostructures present within the composition. Therefore, topical skin compositions can be designed to produce LSPRs irrespective of whether the end user is present in an environment that largely includes indoor or artificial lighting or in an environment that largely includes solar radiation such as in an outdoor setting. Stated another way, the compositions of the present invention can be tuned to deliver a desired LSPR response for indoor and/or outdoor applications, which can be beneficial in providing the end-user with continuous therapeutically effective LSPR responses in instances where the end user is indoor (e.g., home or office) and moves to the outdoors, and vice versa, or changes a given lighting source (e.g., LED to incandescent lighting, and vice versa).

[0046] 1. Structure of Compositions

[0047] The topical compositions of the present invention can be structured or formulated into a variety of different forms. Non-limiting examples include emulsions (e.g., water-in-oil, water-in-oil-in-water, oil-in-water, silicone-in-water, water-in-silicone, oil-in-water-in-oil, oil-in-water-in-silicone emulsions), creams, lotions, solutions (both aqueous and hydro-alcoholic), anhydrous bases (such as lipsticks and powders), gels, masks, peels, and ointments. Variations and other structures will be apparent to the skilled artisan and are appropriate for use in the present invention. Such structures can be prepared by known techniques using standard mixing, heating, and/or cooling steps. By way of example only, the plasmonic noble metal nanostructures can be incorporated into an existing topical skin composition by simple mixing procedures. This would allow the nanostructures to be dispersed throughout the composition. Generally, selected nanostructures of the present invention can be added to an existing formulation under standard mixing procedures, thereby dispersing the nanostructures throughout the existing formulation. A standard in-tank batch mixer (e.g., high shear disperser and low shear agitators) offered by Admix, Inc., Londonderry, N.H. (USA)), can be used. Alternatively, the plasmonic noble metal nanostructures can be incorporated into any given topical skin composition during the preparing of the composition. By way of example, an oil-in-water emulsion-based topical skin composition includes a continuous aqueous phase and a dispersed hydrophobic phase. The stability of such emulsions is typically derived from the use of surfactants, which can work to maintain the existence of the continuous and discontinuous phases and reduce the occurrence of phase separation. Non-limiting examples of such surfactants that can be used in the context of the present invention include nonionic, cationic, anionic, and zwitterionic emulsifiers. By way of example, McCutcheon's Emulsifiers & Detergents 1986 describes a wide variety of non-limiting surfactants that can be used in the context of this invention. Specific non-limiting examples include esters of glycerin, esters of propylene glycol, fatty acid esters of polyethylene glycol, fatty acid esters of polypropylene glycol, esters of sorbitol, esters of sorbitan anhydrides, carboxylic acid copolymers, esters and ethers of glucose, ethoxylated ethers, ethoxylated alcohols, alkyl phosphates, polyoxyethylene fatty ether phosphates, fatty acid amides, acyl lactylates, and soaps. During the preparing of such an emulsion, it is typical to produce the aqueous and oil phases in separate containers followed by mixing the two phases in the presence of a surfactant to obtain said emulsion. The ingredients in such phases can be standard cosmetic ingredients known and used in the cosmetics industry, non-limiting examples of which are provided below. The nanostructures of the present invention can be added to the aqueous and/or to the oily phase prior to mixing the phases together. The phases can then be mixed together under typical mixing, heating, and/or cooling conditions to create the emulsion. Similar, mixing, heating, and/or cooling steps can be used to make other formulations such as those noted above (e.g., creams, lotions, solutions (both aqueous and hydro-alcoholic), anhydrous bases (such as lipsticks and powders), gels, masks, peels, and ointments).

[0048] 2. Cosmetic Ingredients

[0049] The topical skin compositions of the present invention can include a variety of cosmetically acceptable ingredients. By way of example, the CTFA International Cosmetic Ingredient Dictionary and Handbook (2004 and 2008 versions) describes a wide variety of non-limiting cosmetic ingredients that can be used in the context of the present invention. Examples of these ingredients include: fragrance agents (artificial and natural; e.g., gluconic acid, phenoxyethanol, and triethanolamine); dyes and color ingredients (e.g., Blue 1, Blue 1 Lake, Red 40, titanium dioxide, D&C blue no. 4, D&C green no. 5, D&C orange no. 4, D&C red no. 17, D&C red no. 33, D&C violet no. 2, D&C yellow no. 10, and D&C yellow no. 11); flavoring agents/aroma agents (e.g., Stevia rebaudiana (sweetleaf) extract, and menthol); adsorbents; lubricants; solvents; moisturizers (including, e.g., emollients, humectants, film formers, occlusive agents, and agents that affect the natural moisturization mechanisms of the skin); water-repellants; UV absorbers (physical (e.g., titanium dioxide, zinc oxide) and chemical absorbers (e.g., avobenzone, octocrylene, oxybenzone, homosalate, para-aminobenzoic acid (PABA), etc.); essential oils; vitamins (e.g., A, B, C, D, E, and K); trace metals (e.g., zinc, calcium and selenium); anti-irritants (e.g., steroids and non-steroidal anti-inflammatories); botanical extracts (e.g., Aloe vera, chamomile, cucumber extract, Ginkgo biloba, ginseng, rosemary, etc.); anti-microbial agents, antioxidants (e.g., BHT and tocopherol); chelating agents (e.g., disodium EDTA and tetrasodium EDTA); preservatives (e.g., methylparaben and propylparaben); pH adjusters (e.g., sodium hydroxide and citric acid); absorbents (e.g., aluminum starch octenylsuccinate, kaolin, corn starch, oat starch, cyclodextrin, talc, and zeolite); skin bleaching and lightening agents (e.g., hydroquinone and niacinamide lactate); humectants (e.g., sorbitol, urea, methyl gluceth-20, saccharide isomerate, and mannitol); exfoliants, waterproofing agents (e.g., magnesium/aluminum hydroxide stearate); skin conditioning agents (e.g., aloe extracts, allantoin, bisabolol, ceramides, dimethicone, hyaluronic acid, biosaccharide gum-1, ethylhexylglycerin, pentylene glycol, hydrogenated polydecene, octyldodecyl oleate, dipotassium glycyrrhizate, etc.), silicone containing compounds (e.g., polyorganosiloxanes such as dimethicone, cyclomethicone, polysilicone-11, phenyl trimethicone, trimethylsilylamodimethicone, stearoxytrimethylsilane, etc.), and mixtures thereof.

[0050] 3. Amounts of Ingredients

[0051] The topical skin compositions of the present invention can include any amount of the plasmonic noble metal nanostructures, cosmetic ingredients, and/or other ingredients discussed in this specification. The amounts of such ingredients within the compositions can vary depending on the desired effects of the compositions, its tactile properties, its structure, etc. In non-limiting embodiments, the compositions can include, consist essentially of, or consist of, in their final form, for example, at least about 0.0001%, 0.001%, 0.01%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 99% or any range derivable therein, of at least one of the ingredients that are mentioned throughout the specification and claims. In non-limiting aspects, the percentage can be calculated by weight or volume of the total composition.

[0052] 4. Products

[0053] The compositions of the present invention can be incorporated into a variety of cosmetic products. Non-limiting examples of such products include sunscreen products, sunless skin tanning products, hair products (e.g., shampoos, conditioners, colorants, dyes, bleaches, straighteners, and permanent wave products), fingernail products, moisturizing creams, skin creams and lotions, softeners, day lotions, gels, ointments, foundations, night creams, lipsticks and lip balms, cleansers, toners, masks, deodorants, antiperspirants, exfoliating compositions, shaving-related products (e.g., creams, bracers and aftershaves), pre-moistened wipes and washcloths, tanning lotions, bath products such as oils, foot care products such as powders and sprays, skin colorant and make-up products such as foundations, blushes, rouges eye shadows and lines, lip colors and mascaras, baby products (e.g., baby lotions, oils, shampoos, powders and wet wipes), and skin or facial peel products. Additionally, the cosmetic products can be formulated as leave-on or rinse-off products.

C. Use of Topical Skin Compositions

[0054] The topical skin care compositions of the present invention can be used to provide benefits to skin. By way of example, the compositions can be applied to skin (e.g., the face, the neck, the arms, the hands, the chest, the abdomen, the back, the legs, and/or the feet). When the appropriate type of light contacts the composition, the plasmonic nanostructures can absorb light having a certain energy level/wavelength and produce an LSPR response. As explained throughout this specification, the nanostructures can be designed to produce an LSPR(s) in response to artificial light or solar radiation such as natural light or light from a solar simulator. This allows the composition to be designed to work in a targeted lighting environment (e.g., the office environment, the home environment, outdoors, or any combination thereof). Without wishing to be bound by theory, it is believed that the produced LSPR(s) response can be beneficial to skin. By way of example, it is believed that the produced LSPR(s) can reduce the presence of free-radicals and/or oxidants present on the surface of the skin, present within various layers of the skin (e.g., epidermal layer, dermal layer, and/or hypodermal layer), and/or present in various skin cells (e.g., keratinocytes, melanocytes, Merkel cells, and/or Langerhans cells). Again, and without wishing to be bound by theory, it is believed that any given LSPR response can aid in neutralizing the free-radical or oxidative properties of a given free-radical or oxidant by neutralizing unpaired electrons present on the free-radical molecule. By neutralizing these unpaired electrons, the damaging effects of free-radicals on cellular components of the skin such as structural proteins (e.g., collagen, elastin, fibronectin, and laminin), cell membranes, etc., can be reduced. Therefore, it is believed that the compositions of the present invention can help treat, formation of fine lines or wrinkles, sun-damaged skin, skin-inflammatory conditions, skin aging (dark) spots, non-elastic or loosened skin caused by reduced presence of structural proteins, and other skin conditions that may be associated with oxidative damage to skin.

[0055] Still further, the compositions of the present invention can be used to treat skin conditions associated with dry skin, itchy skin, flaky skin, inflamed skin, erythemic skin, pain associated with erythemic skin, sensitive skin, pruritus, spider veins, lentigo, age spots, senile purpura, keratosis, melasma, blotches, nodules, sun damaged skin, dermatitis (including, but not limited to seborrheic dermatitis, nummular dermatitis, contact dermatitis, atopic dermatitis, exfoliative dermatitis, perioral dermatitis, and stasis dermatitis), psoriasis, folliculitis, rosacea, acne, postules, nodules, whiteheads, blackheads, impetigo, erysipelas, erythrism, eczema, sun burns, burned skin, open wounds, skin- inflammatory skin conditions, etc. Even further, the compositions of the present invention through the LSPR activation can be used to (1) reduce tyrosinase activity, TNF- activity, lipoxygenase activity, and/or matrix metallopeptidase (MMP) (e.g., MMP-1, MMP-3, and/or MMP-9) activity in skin cells and/or (2) activate or increase production of collagen, elastin, fibronectin, and/or laminin in skin. By way of example, reduction in tyrosinase activity can be used to treat hyper-pigmented skin, uneven skin, melasmic skin, dark spots, aged spots, sun spots, blotchy skin, etc. Reduction of TNF- activity can be used to treat inflamed skin, red skin, erythemic skin, sun burned skin, burned skin, or other skin-related diseases that are also inflammatory diseases. Reduction in lipoxygenase activity and MMP activity can be used to maintain or reduce collagen breakdown in skin cells and can be used to treat (reduce the appearance of) fine lines and wrinkles, sagging skin, loose skin, or non-elastic skin. Activation or upregulation of collagen, elastin, fibronectin, and/or laminin production in skin can also be used to treat (reduce the appearance of) fine lines and wrinkles, sagging skin, loose skin, or non-elastic skin.

[0056] All of the compositions and methods disclosed and claimed in this specification can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit, and scope of the invention.

EXAMPLES

[0057] The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only, and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters, which can be changed or modified to yield essentially the same results.

Example 1

Prophetic Method of Making Plasmonic Noble Metal Nanoparticles

[0058] Seeded growth is the major method for producing gold nanorods. The sub 2 nm seed is synthesized by adding HAuCl.sub.4 (0.01 M) into a CTAB (0.1 M) solution. After mixing for 30 minutes, chilled NaBH.sub.4 will be added under vigorous stirring. Then the mixture will be heated gently for about 20 minutes at 60 C. to obtain the seed solution. The growth solution will be include 0.1 M CTAB, 0.01 M HAuCl.sub.4, 0.01 M AgNO.sub.3, and 0.1 M Ascorbic acid. The seed solution will be added to the growth solution to obtain gold nanorods. The Aspect ratio will be tuned by adjusting the conditions of the growth solution; including the CTAB concentration, silver ion concentration, HAuCl.sub.4 concentration, growth temperature and duration, and solvent. Potential suppliers of nanoparticles are Nanopartz Inc., Loveland, Colo. (USA), NanoComposix, Inc. San Diego, Calif. (USA) and Sona Nanotech Ltd (Canada).

Prophetic Example 2

Blends of Plasmonic Noble Metal Nanoparticles

[0059] The following procedure can be followed to identify appropriate plasmonic noble metal nanoparticle blends or combinations (e.g., combinations of gold nanorods having different plasmonic peaks) that can be used in the topical skin compositions of the present invention. First, a selection of specific gold nanorods having different aspect ratios can be identified. As discussed above, the differing aspect ratios can result in different plasmonic peaks, with larger aspect ratios resulting in plasmonic peaks that have a longer wavelength and smaller aspect ratios resulting in plasmonic peaks having a shorter wavelength. Second, evaluation of the gold nanorods can be performed by comparing the areas under the absorbance peaks of the nanorods vis--vis a gold spherical nanoparticle. By way of example, FIG. 1 provides an absorbance comparison of gold (Au) nanospheres (NPS) having a diameter of 30 nm with gold (Au) nanorods (NRS) having varying aspect ratios ranging from 2.8 (10 mm28 mm), 3.71 (7 nm26 nm), and 4.5 (8 nm36 nm). The absorbance was normalized to that of a 30 nm NPS at 400 nm. Comparing to the 30 nm Au NPS, the plasmonic peak areas are 2.07 times for the NRS having an aspect ratio of 2.8, and 2.67 times for the NRS having an aspect ratio of 3.71. FIG. 1 confirms that the plasmonic peaks can be tuned with varying the aspect ratio of a given nanorod. By considering the spectra of indoor light sources and outdoor/natural sunlight, blends of plasmonic nanorods can be developed for cosmetic applications such that an LSPR can be produced by a targeted/selected light source. FIGS. 2 to 4 provide lamp spectra for indoor lighting sources (e.g., fluorescent, LED, incandescent and halogen) and the standard solar spectrum at air mass (AM) 1.5, respectively. It is hypothesized that the plasmonic nanorods having a plasmonic peak at about 600 nm to 630 nm can be used for indoor lighting applications. For outdoor lighting applications (e.g., sunlight or solar simulators), a combination of plasmonic nanorods having plasmonic peaks at about 600 nm, 700 nm, and 850 nm, can be used.

Prophetic Example 3

Preparation of a Topical Skin Care Composition and Efficacy of the Composition

[0060] The following includes an in vitro bioassay that can be used to measure the anti-oxidant capacity of any one of the plasmonic noble metal nanostructures or combinations of such nanostructures disclosed in the specification. The assay relies on the ability of a sample formulation having the nanostructures of the present invention to inhibit the oxidation of ABTS (2,2-azino-di-[3-ethylbenzthiazoline sulphonate]) to ABTS+by metmyoglobin. The capacity of the nanostructures present in the formulation to prevent ABTS oxidation is compared with that of Trolox, a water-soluble tocopherol analogue, and is quantified as molar Trolox equivalents. Anti-Oxidant capacity kit # 709001 from Cayman Chemical (Ann Arbor, Mich. USA) can be used for this in vitro bioassay. The protocol can be followed according to manufacturer recommendations. A light source can be used that would trigger an LSPR response from the nanostructures (e.g., natural sunlight, a solar simulator, an LED light source, a fluorescent light source, a halogen light source, a laser light source, or an incandescent light source, etc.) depending on the plasmonic peaks of the nanostructures being tested.