Materials for enhanced photoprotection and methods of making thereof

Abstract

In some examples, the present application relates to a sunscreen composition comprising; zinc oxide; an emollient; and an antioxidant; wherein the zinc oxide exhibits a uniform morphology consisting of tetrapods. In some examples, the present application relates to a method of making a sunscreen composition, the method comprising: providing a composition comprising zinc metal; heating the composition to create zinc oxide tetrapods; mixing the zinc oxide tetrapods with an emollient and an antioxidant to create a dispersion; and heating the dispersion.

Description

[0001] Attorney Docket No. 206030-0335-00WO

[0002] TITLE

[0003] Materials for Enhanced Photoprotection and Methods of Making Thereof

[0004] CROSS REFERENCE TO RELATED APPLICATIONS

[0005] The present application claims priority to U.S. Provisional Application No. 63 / 699,477, filed September 26, 2024, and U.S. Provisional Application No. 63 / 697,712, filed September 23, 2024, all of which applications are incorporated by reference herein in their entireties.

[0006] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0007] This invention was made with government support under NSF Award No. 2136522 awarded by The National Science Foundation. The Government has certain rights in the invention.

[0008] BACKGROUND OF THE INVENTION

[0009] Current sunscreen compositions face several significant limitations that hinder their application and efficiency. One of their primary challenges is photostability, where sustained ultraviolet (UV) radiation over a time period causes a significant drop in sun protection factor (SPF) value. Additionally, commercially available sunscreens often struggle with non-uniform UV absorption, causing uneven photoprotection of the skin.

[0010] There remains a need in the art for sunscreen compositions. The present invention satisfies this unmet need.

[0011] SUMMARY OF THE INVENTION

[0012] In some examples, the present application relates to a sunscreen composition comprising: zinc oxide; an emollient; and an antioxidant; wherein the zinc oxide exhibits a uniform morphology consisting of tetrapods. In some examples, the zinc oxide tetrapods have average diameters between 1 pm and 100 pm. In some examples, the zinc oxide tetrapods have central nodes and arms extending outward from the central nodes, wherein the arms have lengths of between 2 pm and 40 pm. In some examples, the zinc oxide tetrapods are uniformly dispersed throughout the composition. In some examples, the emollient is selected from the group Attorney Docket No. 206030-0335-00WO consisting of C to C15 alkyl benzoate, di octyl adipate, octyl stearate, octyl dodecanol, hexyl laurate, octyldodecyl neopentanoate, cyclomethicone, glycerol oleate, dicapryl ether, dimethicone, phenyl trimethicone, isopropyl myristate, caprylic / capric triglyceride, propylene glycol dicaprylate / dicaprate, decyl oleate, alkyl benzoate, mineral oil, polyolefins, isostearic acid, hydroxystearic acid, oleic acid, linoleic acid, ricinoleic acid, behenic acid, eruicie acid, petrolatum and combinations thereof. In some examples, the antioxidant is selected from the group consisting of sodium metabisulfite, N-acetyl-cysteine, lipoic acid, dihydrolipoic acid, resveratrol, lactoferrin, ascorbic acid, butylated hydroxytoluene, retinoids, tocopherol acetate, tocotrienols, ubiquinone, flavonoids and combinations thereof. In some examples, the composition comprises between 1.0 and 40.0 % (wt / wt) of zinc oxide tetrapods. In some examples, the composition comprises between 0.1 and 60.0 % (wt / wt) of emollient. In some examples, the composition comprises between 1.0 and 40.0 % (wt / wt) of antioxidant. In some examples, the composition has a sun protection factor value greater than 1.4 after 60 minutes of sun exposure. In some examples, the sunscreen composition is comprised in a sunscreen formulation.

[0013] In some examples, the present invention relates to a method of making a sunscreen composition, the method comprising: providing a composition comprising zinc metal; heating the composition to create zinc oxide tetrapods; mixing the zinc oxide tetrapods with an emollient and an antioxidant to create a dispersion; and heating the dispersion. In some examples, the composition further comprises ethanol. In some examples, the ratio of zinc:ethanol is between 3: 1 and 1 : 1. In some examples, the composition further comprises a sacrificial oxidant. In some examples, the step of heating the composition comprises contacting the composition with a flame. In some examples, the step of contacting the composition with a flame is in the presence of oxygen. In some examples, the composition is heated for a temperature of at least 600 °C. In some examples, the zinc oxide tetrapods have a diameter between 1 pm and 100 pm. In some examples, the zinc oxide tetrapods are in an amount of between 1.0 and 40.0% (wt / wt).

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following detailed description of embodiments of the invention will be better understood when read in conjunction with the appended drawings. It should be understood that Attorney Docket No. 206030-0335-00WO the invention is not limited to the precise arrangements and instrumentalities of the embodiments shown in the drawings.

[0016] Figure 1 depicts an illustrative scheme of a creation of a zinc oxide tetrapod photoprotective tetrapod dispersion.

[0017] Figure 2 depicts a series of scanning electron microscopy (SEM) images of tetrapod zinc oxide morphologies.

[0018] Figure 3 depicts an illustrative scheme of flame transport synthesis of zinc oxide tetrapods.

[0019] Figure 4 depicts a SEM image of flame-synthesized ZnO (left) and a transmission electron microscopy image (TEM; right). The SEM image includes a scale bar of 50 pm and the TEM image includes a scale bar of 2 pm.

[0020] Figure 5 depicts a scheme representing the anisotropic growth of ZnO with the wurtzite host lattice (left) and an x-ray diffraction (XRD) spectrum of flame-synthesized ZnO (right).

[0021] Figure 6 depicts an exemplary scheme for preparing a sunscreen dispersion formulation.

[0022] Figure 7 depicts an exemplary scheme for preparing a sunscreen dispersion formulation.

[0023] Figure 8 depicts images of tetrapod dispersion mixtures.

[0024] Figure 9 depicts light microscopy images of 20% (w / w) sunscreen containing flame- synthesized ZnO. Scale bar for left image is 200 pm and scale bar for right image is 100 pm.

[0025] Figure 10 depicts a SEM image of 20% (w / w) sunscreen containing flame-synthesized ZnO. Scale bar is 300 pm.

[0026] Figure 11 depicts a schematic of an oil-in-water (O / W) sunscreen emulsion containing a flame-synthesized ZnO dispersion.

[0027] Figure 12 depicts a chart with data comparing sunscreen sun protection factor (SPF) values over time of hexagonal ZnO (5% (w / w)) sunscreen versus tetrapod ZnO (5% (w / w)) sunscreen.

[0028] Figure 13 depicts a chart with data from absorbance measurements of 20% (w / w) flame- synthesized ZnO sunscreen versus 20% (w / w) solution-gel fabricated (sol gel) ZnO sunscreen.

[0029] Figure 14 depicts a chart with data from reflectance measurements of 20% (w / w) flame- synthesized ZnO sunscreen versus 20% (w / w) sol gel ZnO sunscreen.

[0030] Figure 15 depicts images with colors generated from the absorbance data on Figure 13. Attorney Docket No. 206030-0335-00WO

[0031] Figure 16 depicts a chart with lightness and saturation data values of 20% (w / w) flame- synthesized ZnO sunscreen and 20% (w / w) sol gel ZnO sunscreen on white and black backgrounds.

[0032] DETAILED DESCRIPTION

[0033] It is to be understood that the Figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for the purpose of clarity, many other elements used in sunscreen compositions. Those of ordinary skill in the art may recognize that other elements and / or steps are desirable and / or required in implementing the present invention. However, because such elements and steps are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements and steps is not provided herein. The disclosure herein is directed to all such variations and modifications to such elements and methods known to those skilled in the art.

[0034] As used herein, each of the following terms have the meanings associated with it as specified below. Unless defined otherwise, all technical and scientific terms used herein generally have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0035] The articles “a” and “an” are used herein to refer to one or to more than one (i.e. to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element.

[0036] As used herein, the term “about” will be understood by persons of ordinary skill in the art and will vary to some extent depending on the context in which it is used. As used herein when referring to a measurable value such as an amount, a temporal duration, and the like, the term “about” is meant to encompass variations of ±20% or ±10%, more preferably ±5%, even more preferably ±1%, and still more preferably ±0.1% from the specified value, as such variations are appropriate to perform the disclosed methods.

[0037] Throughout this disclosure, various aspects of the invention can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all Attorney Docket No. 206030-0335-00WO the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 2.7, 3, 4, 5, 5.3, and 6. This applies regardless of the breadth of the range.

[0038] Description

[0039] The present invention relates to materials for enhanced photoprotection and methods of making thereof.

[0040] Sunscreen Composition

[0041] In some embodiments, the present invention relates to a sunscreen composition. In some embodiments, the sunscreen composition comprises zinc oxide, an emollient, and / or an antioxidant. In some examples, the sunscreen composition is comprised in a sunscreen formulation, which may comprise any other suitable ingredients including, but not limited to UV absorbers and / or a UV blockers, emollients, oils, emulsifiers, stabilizers, humectants, preservatives, surfactants, and additives known in the art.

[0042] In some embodiments, the composition further comprises an ultraviolet (UV) absorber and / or a UV blocker, including, but not limited to, titanium oxide, titanium dioxide, calcium phosphate, p-aminobenzoic acid (PABA); padimate O (OD-PABA, octyldimethyl-PABA, o- PABA); phenylbenzimidazole sulfonic acid (Ensulizole, Eusolex 232, PBSA, Parsol H); cinoxate (2 -Ethoxyethyl p-methoxycinnamate), dioxybenzone (Benzophenone-8), oxybenzone (Benzophenone-3, Eusolex 4360, Escalol 567), homosalate (Homomethyl salicylate, HMS), menthyl anthranilate (Meradimate), octocrylene (Eusolex OCR, 2-cyano-3, 3 diphenyl acrylic acid, 2-ethylhexylester), octylmethoxycinnamate (Octinoxate, EMC, OMC, Ethylmethoxycinnamate, Escalol 557, 2-ethylhexyl-paramethoxycinnamate, Parsol MCX), octyl salicylate (Octisalate, 2-Ethylhexyl salicylate, Escalol 587), sulisobenzone (2-Hydroxy-4- Methoxybenzophenone-5-sulfonic acid, 3-benzoyl-4-hydroxy-6-methoxybenzenesulfonic acid, Benzophenone-4, Escalol 577), trolamine salicylate (Triethanolamine salicylate), avobenzone (1- (4-methoxyphenyl)-3-(4-tert-butylphenyl)propane-l, 3-dione, Butyl methoxy dibenzoylmethane, BMDBM, Parsol 1789, Eusolex 9020), ecamsule (Mexoryl SX, Terephthalylidene Dicamphor Attorney Docket No. 206030-0335-00WO

[0043] Sulfonic Acid), 4-methylbenzylidene camphor (Enzacamene, Parsol 5000, Eusolex 6300, MBC), tinosorb M (Bisoctrizole, Methylene Bis-Benzotriazolyl Tetramethylbutylphenol, MBBT), tinosorb S (Bis-ethylhexyloxyphenol methoxyphenol triazine, Bemotrizinol, BEMT, anisotri azine), neo heliopan AP (Bisdisulizole Disodium, Disodium phenyl dibenzimidazole tetrasulfonate, bisimidazylate, DPDT), mexoryl XL (Drometrizole Trisiloxane), benzophenone-9 (Uvinul DS 49, CAS 3121-60-6, Sodium Dihydroxy Dimethoxy Disulfobenzophenone), uvinul T 150 (Octyl triazone, ethylhexyl triazone, EHT), uvinul A plus (Diethylamino Hydroxybenzoyl Hexyl Benzoate), uvasorb HEB (Iscotrizinol, Diethylhexyl butamido triazone, DBT), parsol SLX (Dimethico-diethylbenzalmal onate, Polysilicone-15), isopentenyl-4-m ethoxy cinnamate (Isoamyl p-Methoxy cinnamate, IMC, Neo Heliopan El 000, Amiloxate).

[0044] In some embodiments, the zinc oxide has a morphology including, but not limited to, tetrapods, hexagons, nanorods, spherical nanoparticles, nanosheets, needles, and combinations thereof. In some embodiments, the sunscreen composition comprises zinc oxide tetrapods which comprise a uniform three-dimensional morphology. In some embodiments, the sunscreen composition comprises zinc oxide tetrapods having a central node with at least 4 arms extending outwards at equal angles with respect to each other from the central node. In some embodiments, the zinc oxide tetrapods comprise uniform average lengths, which may be measured from the end of one arm to the end of furthest opposing arm. In some embodiments, the sunscreen composition comprises assemblies of zinc oxide tetrapods with geometrically defined architectures. These assemblies of zinc oxide tetrapods may be ordered and / or non-random.

[0045] In some embodiments, the composition comprises between 0.05 and 50.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises between 0.05 and 30.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises between 5.0 and 30.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises between 5.0 and 25.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises between 10.0 and 25.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises between 15.0 and 25.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises between 1.0 and 10.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises about 4%, about 5%, abou5 6%, about 15% (wt / wt), about 16% (wt / wt), about 17% (wt / wt), about 18% (wt / wt), about 19% Attorney Docket No. 206030-0335-00WO

[0046] (wt / wt), about 20% (wt / wt), about 21% (wt / wt), about 22% (wt / wt), about 23% (wt / wt), about 24% (wt / wt), about 25% (wt / wt), and about 30% (w / w) zinc oxide tetrapods.

[0047] In some embodiments, the composition comprises greater than 0.1% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises greater than 0.5% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises greater than 1.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises greater than 3.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises greater than 5.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises greater than 8.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises greater than 10.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises greater than 12.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises greater than 15.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises greater than 20.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises greater than 25.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises greater than 40.0% (wt / wt) of zinc oxide tetrapods.

[0048] In some embodiments, the composition comprises less than 0.1% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises less than 0.5% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises less than 1.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises less than 3.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises less than 5.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises less than 8.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises less than 10.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises less than 12.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises less than 15.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises less than 20.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises less than 25.0% (wt / wt) of zinc oxide tetrapods. In some embodiments, the composition comprises less than 40.0% (wt / wt) of zinc oxide tetrapods.

[0049] In some embodiments, the zinc oxide tetrapods in the composition have an average length of between 1 nm and 300 pm. In some embodiments, the zinc oxide tetrapods in the composition Attorney Docket No. 206030-0335-00WO have an average length of between 1 nm and 100 gm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of between 1 nm and 10 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of between 1 nm and 1 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of between 1 nm and 500 nm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of between 1 pm and 300 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of between 5 pm and 300 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of between 10 pm and 300 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of between 10 pm and 200 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of between 10 pm and 100 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of between 10 pm and 75 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of between 10 pm and 75 pm.

[0050] In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 1 nm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 50 nm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 100 nm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 150 nm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 500 nm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 1 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 3 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 5 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 10 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 25 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 50 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 75 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 100 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 125 pm. In some Attorney Docket No. 206030-0335-00WO embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 150 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of greater than 300 pm.

[0051] In some embodiments, the zinc oxide tetrapods in the composition have an average length of less than 500 nm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of less than 1 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of less than 3 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of size less than 5 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of less than 10 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of less than 25 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of size less than 50 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of less than 75 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of less than 100 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of less than 125 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of less than 150 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of size less than 300 pm. In some embodiments, the zinc oxide tetrapods in the composition have an average length of less than 500 pm. In some embodiments, the zinc oxide tetrapods have a range of length sizes in the same composition.

[0052] In some embodiments, the zinc oxide tetrapod assemblies have average lengths of between 1 nm to 500 pm, between 500 nm to 350 pm, between 1 pm to 300 pm, between 10 pm to 150 pm, between 30 pm to 120 pm, between 40 pm to 100 pm, and between 40 pm to 80 pm. In some embodiments, the zinc oxide tetrapod assemblies have average lengths of at least 5 nm, at least 500 nm, at least 1 pm, at least 5 pm, at least 10 pm, at least 20 pm, at least 30 pm, at least 40 pm, at least 50 pm, at least 100 pm, at least 120 pm, at least 150 pm, and least 200 pm. In some embodiments, the zinc oxide tetrapod assemblies have average lengths of less than 500 pm, less than 400 pm, less than 300 pm, less than 200 pm, and less than 100 pm. In some embodiments, the zinc oxide tetrapod assemblies have average lengths of about 20 pm, about 40 pm, about 60 pm, about 80 pm, about 100 pm, about 120 pm, and about 140 pm. Attorney Docket No. 206030-0335-00WO

[0053] In some embodiments, the zinc oxide tetrapods comprise a central node and at least four arms extending outward from the central node. In some embodiments, each arm has a length of between 1 nm to 300 pm, between 1 pm to 200 pm between 5 pm to 200 pm between 5 pm to 150 pm between 5 pm to 150 pm between 5 to 100 pm between 5 pm to 75 pm, between 5 pm to 50 pm, between 5 pm to 25 pm, and between 5 pm to 20 pm. In some embodiments, each arm has a length of about 1 pm, about 2 pm, about 3 pm, about 4 pm, about 5 pm, about 6 pm, about 7 pm, about 8 pm, about 9 pm, and about 10 pm. In some embodiments, the zinc oxide tetrapods have arms of different lengths.

[0054] Suitable emollients include those agents known for softening the skin, which include, but are not limited to, hydrocarbons, fatty acids, fatty alcohols, monoglycerides, diglycerides, and triglycerides. Petrolatum is a common hydrocarbon type of emollient conditioning agent. Other hydrocarbons that may be employed include alkyl benzoate, mineral oil, polyolefins such as polydecene, and paraffins, such as isohexadecane. Examples of fatty acids and alcohols include but are not limited to myristic, isostearic, hydroxystearic, oleic, linoleic, ricinoleic, behenic and eruicie acids and alcohols. Ester emollients include, but are not limited to, triglyceride esters, acetoglyceride esters, ethoxylated glycerides, all esters of fatty acids, ether esters, polyhydric alcohol esters and wax esters. Additional emollients or hydrophobic agents include, but are not limited to, Ci2to Cis alkyl benzoate, dioctyladipate, octyl stearate, octyldodecanol, hexyl laurate, octyldodecyl neopentanoate, cyclomethicone, glycerol oleate, dicapryl ether, dimethicone, phenyl trimethicone, isopropyl myristate, caprylic / capric triglycerides, propylene glycol di capryl ate / di caprate and decyl oleate.

[0055] In some embodiments, the composition comprises between 0.05 and 60.0 % (wt / wt) of emollient. In some embodiments, the composition comprises between 0.05 and 55.0 % (wt / wt) of emollient. In some embodiments, the composition comprises between 1.0 and 10.0 % (wt / wt) of emollient. In some embodiments, the composition comprises between 5.0 and 40.0 % (wt / wt) of emollient. In some embodiments, the composition comprises between 10.0 and 40.0 % (wt / wt) of emollient. In some embodiments, the composition comprises between 20.0 and 40.0 % (wt / wt) of emollient. In some embodiments, the composition comprises an emollient in an amount of about 2.0 % (wt / wt), about 4.0 % (wt / wt), about 5.0 % (wt / wt), about 6.0 % (wt / wt), about 8.0 % (wt / wt), about 10.0 % (wt / wt), about 25.0 % (wt / wt), about 28.0 % (wt / wt), about 29.0 % Attorney Docket No. 206030-0335-00WO

[0056] (wt / wt), about 30.0 % (wt / wt), about 31 .0 % (wt / wt), about 32.0 % (wt / wt), about 33.0 % (wt / wt), and / or about 35.0 % (wt / wt).

[0057] In some embodiments, the composition comprises greater than 0.1% (wt / wt) of emollient. In some embodiments, the composition comprises greater than 0.5% (wt / wt) of emollient. In some embodiments, the composition comprises greater than 1.0% (wt / wt) of emollient. In some embodiments, the composition comprises greater than 3.0% (wt / wt) of emollient. In some embodiments, the composition comprises greater than 5.0% (wt / wt) of emollient. In some embodiments, the composition comprises greater than 8.0% (wt / wt) of emollient. In some embodiments, the composition comprises greater than 10.0% (wt / wt) of emollient. In some embodiments, the composition comprises greater than 12.0% (wt / wt) of emollient. In some embodiments, the composition comprises greater than 15.0% (wt / wt) of emollient. In some embodiments, the composition comprises greater than 20.0% (wt / wt) of emollient. In some embodiments, the composition comprises greater than 25.0% (wt / wt) of emollient. In some embodiments, the composition comprises greater than 40.0% (wt / wt) of emollient.

[0058] In some embodiments, the composition comprises less than 0.1% (wt / wt) of emollient. In some embodiments, the composition comprises less than 0.5% (wt / wt) of emollient. In some embodiments, the composition comprises less than 1.0% (wt / wt) of emollient. In some embodiments, the composition comprises less than 3.0% (wt / wt) of emollient. In some embodiments, the composition comprises less than 5.0% (wt / wt) of emollient. In some embodiments, the composition comprises less than 8.0% (wt / wt) of emollient. In some embodiments, the composition comprises less than 10.0% (wt / wt) of emollient. In some embodiments, the composition comprises less than 12.0% (wt / wt) of emollient. In some embodiments, the composition comprises less than 15.0% (wt / wt) of emollient. In some embodiments, the composition comprises less than 20.0% (wt / wt) of emollient. In some embodiments, the composition comprises less than 25.0% (wt / wt) of emollient. In some embodiments, the composition comprises less than 40.0% (wt / wt) of emollient. In some embodiments, the composition comprises less than 50.0% (wt / wt) of emollient.

[0059] Examples of antioxidants include, but are not limited to, water-soluble antioxidants such as sulfhydryl compounds and their derivatives (e.g., sodium metabisulfite and N-acetyl-cysteine), lipoic acid and dihydrolipoic acid, resveratrol, lactoferrin, and ascorbic acid and ascorbic acid derivatives (e.g., ascorbyl palmitate and ascorbyl polypeptide). Oil-soluble antioxidants suitable Attorney Docket No. 206030-0335-00WO for use in the compositions of this invention include, but are not limited to, Vitamin E, butylated hydroxytoluene, retinoids (e.g., retinol and retinyl palmitate), tocopherols, tocopherol acetate, tocotrienols, and ubiquinone. Natural extracts containing antioxidants suitable for use in the compositions of this invention, include, but are not limited to, extracts containing flavonoids and isoflavonoids and their derivatives (e.g., genistein and diadzein), extracts containing resveratrol and the like. Examples of such natural extracts include grape seed, green tea, pine bark, and propolis.

[0060] In one embodiment, the antioxidant is tocopherol. Suitable forms of tocopherol include, but are not limited to, alpha, beta, delta, and gamma tocopherols, salts or derivatives of tocopherols are also included such as tocopherol acetate, tocopherol sulfate, tocopherol succinate, tocopherol nicotinate, tocopherol palmitate, tocopherol allophanate, tocopherol phosphate, tocopherol quinone, halogenated tocopherols, tocopherol esters, and tocopherol stereoisomers.

[0061] In some embodiments, the composition comprises between 0.1 and 40.0 % (wt / wt) of antioxidant. In some embodiments, the composition comprises between 0.1 and 15.0 % (wt / wt) of antioxidant. In some embodiments, the composition comprises between 0.1 and 10.0 % (wt / wt) of antioxidant. In some embodiments, the composition comprises between 0.1 and 5.0 %

[0062] (wt / wt) of antioxidant. In some embodiments, the composition comprises between 0.1 and 3.0 %

[0063] (wt / wt) of antioxidant. In some embodiments, the composition comprises between 0.1 and 2.0 %

[0064] (wt / wt) of antioxidant. In some embodiments, the composition comprises between 0.1 and 1.0 %

[0065] (wt / wt) of antioxidant. In some embodiments, the composition comprises an antioxidant in an amount of about 0.2 % (wt / wt), about 0.3 % (wt / wt), about 0.4 % (wt / wt), about 0.5 % (wt / wt), about 0.6 % (wt / wt), about 0.7 % (wt / wt), about 1.0 % (wt / wt), about 2.0 % (wt / wt), about 3.0 % (wt / wt), about 4.0 % (wt / wt), and / or about 5.0 % (wt / wt).

[0066] In some embodiments, the composition comprises greater than 0.1% (wt / wt) of antioxidant. In some embodiments, the composition comprises greater than 0.5% (wt / wt) of antioxidant. In some embodiments, the composition comprises greater than 1.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises greater than 3.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises greater than 5.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises greater than 8.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises greater than 10.0% (wt / wt) of Attorney Docket No. 206030-0335-00WO antioxidant. In some embodiments, the composition comprises greater than 12.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises greater than 15.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises greater than 20.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises greater than 25.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises greater than 40.0% (wt / wt) of antioxidant.

[0067] In some embodiments, the composition comprises less than 0.1% (wt / wt) of antioxidant. In some embodiments, the composition comprises less than 0.5% (wt / wt) of antioxidant. In some embodiments, the composition comprises less than 1.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises less than 3.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises less than 5.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises less than 8.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises less than 10.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises less than 12.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises less than 15.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises less than 20.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises less than 25.0% (wt / wt) of antioxidant. In some embodiments, the composition comprises less than 40.0% (wt / wt) of antioxidant.

[0068] In one embodiment, the composition has a sun protection factor (SPF) value greater than 0.1 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 0.5 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.0 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.1 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.2 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.25 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.3 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.35 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.4 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.45 after 60 minutes of sun exposure. Attorney Docket No. 206030-0335-00WO

[0069] In one embodiment, the composition has a sun protection factor value greater than 1.5 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.55 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.56 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.57 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.58 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value greater than 1.59 after 60 minutes of sun exposure. In one embodiment, the composition has a sun protection factor value of about 1.59 after 60 minutes of sun exposure.

[0070] The composition may further comprise one or more other cosmetically acceptable active agents including, but not limited to, oils, anti-acne agents, shine control agents, anti-microbial agents, anti-inflammatory agents, anti-mycotic agents, anti-parasite agents, external analgesics, sunscreens, photoprotectors, keratolytic agents, surfactants, moisturizers, nutrients, energy enhancers, anti-perspiration agents, astringents, deodorants, firming agents, anti-callous agents, and agents for skin conditioning.

[0071] Suitable surfactants include, but are not limited to, nonionic surfactant such as cetyl alcohol, cetearyl alcohol, polyoxyethylene sorbitan monolaureate (TWEEN®, (i.e., TWEEN®20), polyoxyethylene 23 lauryl ether (BRIJ®-35) or poly oxy ethylated octyl phenol (TRITON®); a zwitterionic surfactant such as 3-((3-cholamidopropyl) dimethylammonio)-! -propane sulfonate (CHAPS®); a cationic surfactant; or an anionic surfactant such as cholate, deoxycholate, sodium dodecyl sulfate, or TWEEN®-80.

[0072] Suitable oils include, but are not limited to, an animal oil, fish oil, a vegetable oil, a mineral oil, olive oil, sunflower oil, sesame oil, almond oil, com oil, orange oil, lime oil, black pepper oil, nutmeg oil, basil oil, rosemary oil, clove oil, grapefruit oil, fennel oil, coriander oil, bergamot oil, cinnamon oil, lemon oil, peppermint oil, garlic oil, thyme oil, maijoram oil, lemongrass oil, ginger oil, cardamon oil, liquid paraffin, cotton seed oil, peanut oil, nut oil, soy, rapeseed oil, vitamin E oil and derivatives thereof, including Vitamin E TPGS (d-alpha tocopheryl polyethylene glycol 1000 succinate), tallow-derived oil, silicone oil, castor oil, squalane oil, squalene oil, or any mixture thereof.

[0073] Method of Making a Sunscreen Composition Attorney Docket No. 206030-0335-00WO

[0074] In some embodiments, the present invention relates to a method of making a sunscreen composition. In some embodiments, the method comprises: providing a composition comprising zinc metal; heating the composition to create zinc oxide tetrapods; mixing the zinc oxide tetrapods with an emollient and an antioxidant to create a dispersion; and heating the dispersion. In some embodiments, the zinc oxide tetrapods, the emollient, and the antioxidant are described elsewhere herein. The zinc metal may be in the form of zinc microparticles and / or zinc powder.

[0075] In some embodiments, the composition further comprises a sacrificial oxidant including, but not limited to polyvinyl butyral (PVB), ethanol, and combinations thereof.

[0076] In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio between 5: 1 and 1 :5. In some embodiments the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio between 4: 1 and 1:2. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio between 3: 1 and 1 : 1. In some embodiments, the composition comprises zinc microp rticles and ethanol in a zinc: ethanol ratio of about 2: 1.

[0077] In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio greater than 1 :5. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio greater than 1 :3. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio greater than 1 :2. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio greater than 1 : 1. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio greater than 2: 1. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio greater than 3:1. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio greater than 4: 1. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio greater than 5: 1. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio greater than 8:1.

[0078] In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio less than 1 :5. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio less than 1 :3. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio less than 1 :2. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol Attorney Docket No. 206030-0335-00WO ratio less than 1 : 1 . In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio less than 2: 1. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio less than 3: 1. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio less than 4: 1. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio less than 5: 1. In some embodiments, the composition comprises zinc microparticles and ethanol in a zinc:ethanol ratio less than 8: 1.

[0079] In some embodiments, the composition comprising the zinc metal is heated to a temperature of at least 100 °C, at least 200 °C, at least 300 °C, at least 400 °C, at least 500 °C, at least 600 °C, at least 700 °C, at least 800 °C, and at least 900 °C. In some embodiments, the composition comprising the zinc metal is heated to a temperature of less than 3000 °C, less than 2000 °C, less than 1800 °C, less than 1500 °C, less than 1200 °C, less than 1100 °C, and less than 1000 °C. In some embodiments, the composition comprising the zinc metal is heated to a temperature of between about 100 °C and 3000 °C, between about 200 °C and 2000 °C, between about 300 °C and 2000 °C, between about 400 °C and 1500 °C, between about 500 °C and 1200 °C, between about 600 °C and 1200 °C, between about 700 °C and 1100 °C, and between about 800 °C and 1000 °C. In some embodiments, the composition comprising the zinc metal is heated to a temperature of about 700 °C, about 800 °C, about 900 °C, about 1000 °C, and about 1100 °C.

[0080] In some embodiments, the composition comprising the zinc metal is heated for at least 1 min, at least 10 min, at least 20 min, at least 30 min, at least 40 min, at least 50 min, at least 60 min, at least 70 min, at least 80 min, and at least 90 min. In some embodiments, the composition comprising the zinc metal is heated for less than 300 min, less than 250 min, less than 220 min, less than 200 min, less than 180 min, less than 150 min, less than 120 min, and less than 100 min. In some embodiments, the composition comprising the zinc metal is heated for between about 1 min and 500 min, about 5 min and 400 min, about 10 min and 300 min, about 20 min and 250 min, about 30 min and 200 min, about 50 min and 200 min, about 70 min and 150 min, and about 80 min and 120 min. In some embodiments, the composition comprising the zinc metal is heated for about 60 min, about 70 min, about 80 min, about 90 min, about 100 min, about 110 min, about 120 min, and about 130 min. Attorney Docket No. 206030-0335-00WO

[0081] In some embodiments, the step of heating the composition comprising zinc metal comprises contacting the composition with a flame in the presence of oxygen. In some embodiments, the step of heating the composition comprising zinc metal to a high temperature is done in a furnace such that the zinc microparticles sublimate in the furnace and create the zinc oxide tetrapods. In some embodiments, the step of heating the zinc metal to a high temperature is done in a microwave.

[0082] EXPERIMENTAL EXAMPLES

[0083] The invention is further described in detail by reference to the following experimental examples. These examples are provided for purposes of illustration only, and are not intended to be limiting unless otherwise specified. Thus, the invention should in no way be construed as being limited to the following examples, but rather, should be construed to encompass any and all variations which become evident as a result of the teaching provided herein.

[0084] Without further description, it is believed that one of ordinary skill in the art can, using the preceding description and the following illustrative examples, make and utilize the materials, devices, and kits of the present invention and practice the claimed methods. The following working examples, therefore, specifically point out exemplary embodiments of the present invention, and are not to be construed as limiting in any way the remainder of the disclosure.

[0085] Example 1 : Materials for Enhanced Photoprotection

[0086] A material dispersion that provides superior sun protection in sunscreens when compared to similar ultraviolet (UV) filter dispersions was developed. The sunscreen material is composed of UV-absorbing nanocrystals created by heating zinc (Zn) at high temperatures, then suspended within a skin-soothing emollient and antioxidant (Figure 1). Compared to hexagonal-shaped zinc oxide (ZnO) and conventional nanoparticles use in sunscreen applications, ZnO tetrapods have superior optical properties in the critical UV range, and significantly advantageous properties in terms of nanoparticle aggregation. ZnO tetrapods are also known to have useful antimicrobial and antiviral properties.

[0087] Zinc oxide (ZnO) tetrapods exhibit needle-like projections protruding from a central core (Figure 2). The tetrapodal shape is obtained by using flame transport synthesis, which involves heating Zn microparticles at a high temperature via a solid-vapor-solid growth process (Figure Attorney Docket No. 206030-0335-00WO

[0088] 3). Ethanol was employed as a sacrificial oxidant to enable combustion of the Zn precursor at high temperatures. Polyvinyl butyral was contemplated for use as sacrificial oxidant. Upon heating a furnace containing a 2: 1 mixture of zinc microparticles and ethanol to temperatures above 900 °C for 90 minutes, the flame generated produces a vapor, which then converts the zinc precursors to oxidized ZnO tetrapodal nanostructures. Figure 4 shows scanning electron microscopy images (SEM) and transmission electron microscopy (TEM) images of 0.1 g of flame-synthesized ZnO tetrapods. Figure 5 further depicts the anisotropic growth of ZnO within the wurtzite host lattice and an x-ray diffraction (XRD) spectrum of the flame-synthesized ZnO tetrapods. The inventive ZnO tetrapods are higher in crystallinity than other ZnO types used in conventional sunscreens. The ZnO tetrapods were then used to create a dispersion for usage in sunscreens.

[0089] The ZnO tetrapods were then incorporated into a dispersion that can be used for sunscreen formulations. In one demonstration, a 50 g dispersion was prepared by mixing 20 g of zinc oxide tetrapods, 29.75 mL of capryl ic / capric triglyceride, and 0.25 mL of tocopheryl acetate in a beaker. The mixture was then heated to 70 °C with agitation for 120 seconds and stirred at 200 rpm (Figure 6 and Figure 7). Once uniform, the ZnO tetrapod dispersion can be incorporated into a sunscreen formulation for use (Figure 8). Light microscope images of sunscreen containing this dispersion are shown in Figure 9. Figure 10 shows a SEM image of sunscreen containing this dispersion. Interlocking ZnO aggregates are visible in the SEM image. A schematic of an oil-in water sunscreen emulsion containing a flame-synthesized ZnO dispersion is shown in Figure 11.

[0090] Advantageous Effects

[0091] ZnO is utilized in cosmetic applications and often produced by wet chemistry, resulting in a non-uniform size and shape morphology. This results in non-uniform UV absorption when used in sunscreen formulations. Lack of uniformity in morphology of powdered ZnO nanocrystals also contributes to destabilization (separation and visible agglomeration of ZnO nanocrystals) in sunscreen formulations over time due to the difficulty of uniform suspension of ZnO throughout the formula. When ZnO nanocrystals aggregate over time or destabilize the sunscreen lotion in which they are dispersed, less UV radiation is absorbed, and therefore there is uneven photoprotection of the skin. However, ZnO tetrapods form 3D structures when they Attorney Docket No. 206030-0335-00WO contact one another (Figure 2 and Figure 4), which is advantageous for forming thin films on the skin for photoprotection.

[0092] When compared to an identically prepared dispersion that utilizes ZnO obtained by wet chemistry methods (sol gel), the tetrapod photoprotective dispersion exhibits greater absorbance in the UV, in addition to higher SPF values when exposed to sustained UV radiation over 60 minutes (Figure 12). Figure 13 shows the absorbance profile of flame-synthesized ZnO sunscreen versus sol gel ZnO sunscreen. Figure 14 shows the reflectance profile of 20% (w / w) flame-synthesized ZnO sunscreen versus 20% (w / w) sol gel ZnO sunscreen. The sun protection factor (SPF) of 20% (w / w) flame-synthesized ZnO sunscreen was calculated according to the Mansur equation to be 22.2. Meanwhile, the SPF of 20% (w / w) sol gel ZnO sunscreen was calculated to be 20.6. Flame-synthesized ZnO sunscreen clearly outperforms sol gel ZnO sunscreen by exhibiting superior stability in the presence of UV radiation, and therefore superior photoprotective properties when used in a sunscreen formulations. The absorbance data was then used to generate L*, a*, and b* color values and this data is depicted in Figure 15. TheUV / Vis- simulated color of 20% (w / w) flame-synthesized ZnO Sunscreen generated a warmer hue. Meanwhile, the UV / Vis-simulated color of 20% (w / w) sol gel ZnO sunscreen generated a chalky white hue. Lightness versus saturation profiles of each sunscreen are depicted in Figure 16. Lightness and saturation values were then obtained using a colorimeter to measure L*, a*, and b* color values. Sol gel sunscreens were grayer and bluer (white cast), whereas flame-synthesized sunscreens were warmer and more yellow for better blending.

[0093] The demonstrated tetrapod photoprotective dispersion contains caprylic / capric triglyceride and tocopheryl acetate (Vitamin E), which are both inexpensive, yet highly utilized materials in the cosmetic industry that are generally well -tolerated by most skin tones and types. Furthermore, these materials are globally approved for cosmetic usage. Dispersion of the ZnO tetrapods in the demonstrated caprylic / capric triglyceride and tocopheryl acetate mixture allows for a highly attractive alternative to other ZnO dispersions on the market, free of using volatile or undesirable cosmetic ingredients that may deter consumers from usage.

[0094] The disclosures of each and every patent, patent application, and publication cited herein are hereby incorporated herein by reference in their entirety. While this invention has been disclosed with reference to specific embodiments, it is apparent that other embodiments and Attorney Docket No. 206030-0335-00WO variations of this invention may be devised by others skilled in the art without departing from the true spirit and scope of the invention. The appended claims are intended to be construed to include all such embodiments and equivalent variations.

Claims

Attorney Docket No. 206030-0335-00WOCLAIMSWe claim:

1. A sunscreen composition comprising: zinc oxide; an emollient; and an antioxidant; wherein the zinc oxide exhibits a uniform morphology consisting of tetrapods.

2. The composition of claim 1, wherein the zinc oxide tetrapods have average diameters between 1 pm and 100 pm.

3. The composition of claim 1, wherein the zinc oxide tetrapods have central nodes and arms extending outward from the central nodes, wherein the arms have lengths of between 2 pm and 40 pm.

4. The composition of claim 1, wherein the zinc oxide tetrapods are uniformly dispersed throughout the composition.

5. The composition of claim 1, wherein the emollient is selected from the group consisting of C to C15 alkyl benzoate, dioctyladipate, octyl stearate, octyldodecanol, hexyl laurate, octyldodecyl neopentanoate, cyclomethicone, glycerol oleate, dicapryl ether, dimethicone, phenyl trimethicone, isopropyl myristate, caprylic / capric triglyceride, propylene glycol di capryl at e / di caprate, decyl oleate, alkyl benzoate, mineral oil, polyolefins, isostearic acid, hydroxystearic acid, oleic acid, linoleic acid, ricinoleic acid, behenic acid, eruicie acid, petrolatum and combinations thereof.

6. The composition of claim 1, wherein the antioxidant is selected from the group consisting of sodium metabisulfite, N-acetyl-cysteine, lipoic acid, dihydrolipoic acid, resveratrol, lactoferrin, ascorbic acid, butylated hydroxy toluene, retinoids, tocopherol acetate, tocotrienols, ubiquinone, flavonoids and combinations thereof.Attorney Docket No. 206030-0335-00WO7. The composition of claim 1, wherein the composition comprises between 1 .0 and 40.0 % (wt / wt) of zinc oxide tetrapods.

8. The composition of claim 1, wherein the composition comprises between 0.1 and 60.0 % (wt / wt) of emollient.

9. The composition of claim 1, wherein the composition comprises between 1.0 and 40.0 % (wt / wt) of antioxidant.

10. The composition of claim 1, wherein the composition has a sun protection factor value greater than 1.4 after 60 minutes of sun exposure.

11. A sunscreen formulation comprising the sunscreen composition of claim 1.

12. A method of making a sunscreen composition, the method comprising: providing a composition comprising zinc metal; heating the composition to create zinc oxide tetrapods; mixing the zinc oxide tetrapods with an emollient and an antioxidant to create a dispersion; and heating the dispersion.

13. The method of claim 12, where in the composition further comprises ethanol.

14. The method of claim 13, wherein the ratio of zinc:ethanol is between 3 : 1 and 1 : 1.

15. The method of claim 12, wherein the composition further comprises a sacrificial oxidant.

16. The method of claim 12, wherein the step of heating the composition comprises contacting the composition with a flame.Attorney Docket No. 206030-0335-00WO17. The method of claim 16, wherein the step of contacting the composition with a flame is in the presence of oxygen.

18. The method of claim 12, wherein the composition is heated for a temperature of at least 600 °C.

19. The method of claim 12, wherein the zinc oxide tetrapods have a diameter between 1 pm and 100 pm.

20. The method of claim 12, wherein the zinc oxide tetrapods are in an amount of between 1.0 and 40.0% (wt / wt).

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