Metal nanoparticles and methods of making and compositions thereof

Abstract

A method of synthesizing a nanoparticle is described. The method comprises the steps of: providing a metal solution comprising at least one metal precursor and at least one solvent; providing a fatty acid solution comprising at least one fatty acid and at least one solvent; combining the metal solution and the fatty acid solution to provide a combined solution; and collecting the nanoparticle from the combined solution. Also described is a nanoparticle synthesized using the method, and compositions comprising the nanoparticle.

Description

[0001]Attorney Docket No.: 047162-5361-00WO METAL NANOPARTICLES AND METHODS OF MAKING AND COMPOSITIONS THEREOF CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 627,312, filed January 31, 2024, the entire contents of which are incorporated herein by reference. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with government support under EEC-1449500 awarded by the National Science Foundation. The government has certain rights in the invention. BACKGROUND OF THE INVENTION Nanotechnology is poised to unlock transformative advances in fields like electronics, medicine, and energy. At the foundation of nanotechnology is nanomanufacturing, the precise and controlled manipulation of materials at the nanoscale. Existing nanomanufacturing methods are low-throughout with most inorganic nanoparticles being synthesized in batches, requiring high-cost skilled labor and large characterization costs to address batch to batch variation and the lack of online manufacturing control. These time intensive and costly manufacturing processes limit the application of many proven nanomaterials by precluding their production at a meaningful scale. Affordable, customizable nanoparticle manufacturing would drastically lower barriers-to-entry for technologies poised to play an enabling role for industries from healthcare to green energy to agriculture. For instance, better nanoparticles would: improve agriculture with advanced nanofertilizers with fewer adverse environmental impacts (iron oxide, titanium dioxide, magnesium oxide); enable functionalized membranes and nanoengineered adsorbents for next-generation water treatment and purification; encourage heightened in-situ treatment and targeted remediation of environmental contaminants (iron oxide, zinc, and titanium oxide nanoparticles); generate an expansive nanomaterial library to evaluate the toxicological profiles of nanoengineered materials; lower costs of advanced cancer treatments and next-generation Attorney Docket No.: 047162-5361-00WO diagnostic imaging (gold nanoparticles); accelerate prototyping of energy storage methods (silicon nanoparticles); and increase the efficiency of catalytic processes for the hydrogen economy and electrochemical CO2conversion (palladium, gold, and copper nanoparticles, as well as shape and size-controlled mixtures thereof). Thus, there is a need in the art for improved compositions of and methods for inorganic nanoparticles. This invention satisfies this unmet need. SUMMARY OF THE INVENTION The present invention provides a method of synthesizing a nanoparticle, comprising the steps of: providing a metal solution comprising at least one metal precursor and at least one solvent; providing a fatty acid solution comprising at least one fatty acid and at least one solvent; combining the metal solution and the fatty acid solution to provide a combined solution; and collecting the nanoparticle from the combined solution. In some embodiments, the at least one metal precursor comprises an element selected from the group consisting of palladium, manganese, silver, gold, zinc, copper, iron, cobalt, nickel, platinum, any oxidation state thereof, and any combination thereof. In some embodiments, the at least one metal precursor comprises gold. In some embodiments, the at least one metal precursor is selected from the group consisting of chloroauric acid, iron chloride, copper chloride, manganese chloride, chloroplatinic acid, sodium tetrachloroplatinate, and combinations thereof. In some embodiments, the metal solution has a metal precursor concentration of between 0.1 mM and 50 mM. In some embodiments, the at least one fatty acid is selected from the group consisting of oleic acid, palmitoleic acid, linoleic acid, palmitic acid, lauric acid, vaccenic acid paullinic acid, elaidic acid, gondoic acid, erucic acid, nervonic acid, mead acid, myristic acid, salts thereof, and esters thereof. In some embodiments, the fatty acid solution has a fatty acid concentration of between 30 mM and 300 mM. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is between 3:1 and 30:1. In some embodiments, the fatty acid solution further comprises a salt of the at least one fatty acid. In some embodiments, the concentration of the nanoparticle in the combined solution is between 1 mM and 20 mM. Attorney Docket No.: 047162-5361-00WO In some embodiments, the step of providing a fatty acid solution further comprises the step of heating the fatty acid solution. In some embodiments, the step of combining the metal solution and the fatty acid solution further comprises the step of heating the combined solution. In some embodiments, the combined solution is heated to a final temperature between 30 °C to 100 °C. In some embodiments, the step of collecting the nanoparticle from the combined solution comprises the step of centrifuging the combined solution. In some embodiments, the method further comprises the step of combining the nanoparticle with a capping agent. In some embodiments, the capping agent comprises at least one functionality selected from the group consisting of a thiol, polyethylene glycol (PEG), and a fluorescein dye. In some embodiments, the present invention provides a nanoparticle synthesized using the method. In some embodiments, the nanoparticle has a diameter of about 5 nm to about 40 nm. In some embodiments, the present invention provides a composition comprising the nanoparticle and a solvent. In some embodiments, the solvent is selected from the group consisting of Dulbecco’s Modified Eagle Medium (DMEM), Rosswell Park Memorial Institute Medium (RPMI), and Minimum Essential Medium (MEM). BRIEF DESCRIPTION OF THE DRAWINGS 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 the invention is not limited to the precise arrangements and instrumentalities of the embodiments shown in the drawings. Figure 1 depicts transmission electron microscopy (TEM) micrographs, particle size distributions, and distribution statistics. Figure 2, comprising Figure 2A through Figure 2C, depicts representative stability testing and zeta potential. Figure 2A depicts aggregation kinetics in 1x PBS. Figure 2B depicts the zeta potential as a function of pH for purified oleate bilayer coated AuNPs in 27 / 1 NaOl / Au- precursor synthesis ratios. Figure 2C depicts the zeta potential as a function of pH for purified oleate bilayer coated AuNPs in 9 / 1 NaOl / Au-precursor synthesis ratios. Attorney Docket No.: 047162-5361-00WO Figure 3, comprising Figure 3A through Figure 3P, depicts representative time- resolved multiplexed spectroscopy. Figure 3A through Figure 3G depict absorbance evolution of further oleate / Au-precursor ratios at 40 ºC. Figure 3H depicts further correction factors for absorbance correction with turbidity as measured at 800 nm. Figure 3I through Figure 3O depict absorbance evolution of further oleate / Au-precursor ratios with upward pH adjustment to ≈ 9.1. Figure 3P depicts ratio of absorbance evolution between 530 nm and 500 nm. Figure 4, comprising Figure 4A through Figure 4I, depicts AuNP synthesis at different NaOl / Au ratios and temperatures. Figure 4A depicts spectral development for an oleate / precursor ratio of 27 / 1 at 40 ºC. Figure 4B depicts peak wavelength shift. Figure 4C depicts absorbance development. Figure 4D depicts spectral development for capping agent to Au precursor ratio 27 / 1 at 70 ºC. Figure 4E depicts spectral development for capping agent to Au precursor ratio 9 / 1 at 40 ºC. Figure 4F depicts spectral development for capping agent to Au precursor ratio 9 / 1 at 70 ºC. Spectra shown at intervals of 0.3, 5, 10, 15, 20, 30, 45, 60, 120, 180, 240, and 360 min in ascending order. Figure 4G depicts pH development during AuNP synthesis, measured in a round bottom flask setup for ratio 27 / 1. Figure 4H depicts pH development during AuNP synthesis, measured in a round bottom flask setup for ratio 9 / 1. Figure 4H depicts a representative titration curve of sodium oleate and suggested ranges of self-assembly forms (Suga et al., 2016, Langmuir, 32, 7606). Figure 5, comprising Figure 5A through Figure 5F, depicts representative reaction progression in a 96-well plate reader, 12-fold multiplicates (12 wells) per oleate / precursor ratio. Figure 5A depicts absorbance at 530 nm adjusted by turbidity. Figure 5B depicts absorbance at 800 nm adjusted by turbidity. Figure 5C depicts absorbance at 530 nm adjusted by turbidity. Figure 5D depicts the ratio of LSPR absorbances at 530 nm and 500 nm over 24 h. Figure 5E depicts micrographs of different oleate / precursor ratios with and without upward pH adjustment synthesized in conventional glassware at 25 ml scale and 70 °C. Figure 5F depicts particle sizes for aliquots at 3 h and 24 h for pH unadjusted and adjusted samples at ratio 9 / 1 shown in Figure 5E. Welch’s unpaired, unequal variance t-test, **** corresponds to P ≤ 0.0001, N > 450. Coefficients of size variation for particles obtained for 9 / 1 pH adj.3 h, 9 / 1 pH adj.24 h, 9 / 13 h, and 9 / 124 h are 19.7%, 29.3%, 19.0%, and 21.3%, respectively. Figure 6, comprising Figure 6A through Figure 6D, depicts a schematic for multiplexed fatty-acid self-assembly mediated gold nanoparticle synthesis. Figure 6A depicts Attorney Docket No.: 047162-5361-00WO thermocycler-based work process for gold nanoparticle synthesis. Figure 6B depicts transmission electron microscopy (TEM)-based particle diameter (ferret) for different NaOl / HAuCl4 ratios, over 1000 particles were counted for each ratio. Welch’s unpaired, unequal variance t-test, **** corresponds to P ≤ 0.0001. Coefficients of size variation for particles obtained of ratios 27 / 1, 15 / 1, 12 / 1, and 9 / 1 are 11.9%, 13.0%, 16.9%, and 30.1%, respectively. Figure 6C depicts photographs of multiplexed gold nanoparticle synthesis in a 96-well thermocycler plate and a 96- well plate reader plate and synthesis progression over 24 h. Controls are 1.100 mM HAuCl4, 2. 10 mM HAuCl4, 3.300 mM NaOl, 4. MilliQ water. Figure 6D depicts TEM micrographs of particles synthesized at different ratios corresponding to Figure 6B. Figure 7 depicts the influence on synthesis temperature on particle size in thermocycler-based synthesis for 27 / 1 ratio. N = 2705, 2204, and 1817, respectively. CV = 16.9%, 21,7%, and 14.0%, respectively. Welch’s unpaired, unequal SD t-test, **** corresponds to P ≤ 0.0001. Figure 8, comprising Figure 8A and Figure 8B, depict representative micrographs of AuNPs. Figure 8A depicts a micrograph of 9 / 1 ratio AuNP including anisotropic particles showing oleate surface coating. Figure 8B depicts a micrograph of 4.5 / 1 ratio AuNPs including anisotropic particles showing oleate surface coating. Figure 9, comprising Figure 9A through Figure 9D, depicts a representative synthesis scaleup to 0.5 g Au. Figure 9A depicts a round bottom flask setup prior to Au- precursor injection. Figure 9B depicts the reaction 24 h post-injection. Figure 9C depicts glassware post sample transfer. Figure 9D depicts glassware post sample transfer after double rinsing with milliQ water. Figure 10, comprising Figure 10A through Figure 10D, depicts data from the scale-up of 27 / 1 NaOL / Au synthesis ratio. Figure 10A depicts the particle size distribution obtained from thermocycler and scale-up synthesis for 27 / 1 ratio (250 ml, 0.49 g Au scale), NThermocycler= 2515, NScale-up= 1564. Figure 10B depicts resulting ultraviolet visible (UV-Vis) spectra after triple washing and dilution to OD520=1. Figure 10C depicts high-magnification TEM micrograph of 27 / 1 ratio AuNPs synthesized. Figure 10D depicts an aliquot of scale-up synthesis. Figure 11, comprising Figure 11A through Figure 11C, depicts results of ligand exchange with FITC-PEG-SH. Figure 11A depicts the ligand exchange process. Figure 11B Attorney Docket No.: 047162-5361-00WO depicts fluorescence intensity of FITC-PEG-SH functionalized gold nanoparticles and wash supernatant. Figure 11C depicts FTIR spectra for sodium oleate (powder), purified post synthesis oleic acid bilayer capped gold nanoparticles (4x washed by centrifugations), gold nanoparticles after capping layer exchange with fluorescent PEG thiol dye FITC-PEG-SH (5k) (3x washed after 72h incubation), and after an additional purification step (4x washed after 72h incubation). Figure 12, comprising Figure 12A through Figure 12D, depicts room temperature stability and autoclaving stability of oleate bilayer-coated gold nanoparticles. Figure 12A depicts a representative UV-vis spectrum before and after autoclaving for 20 minutes for freshly prepared oleate-bilayer coated AuNPs. Figure 12B depicts a representative UV-vis spectrum before and after autoclaving for 20 minutes for oleate-bilayer coated AuNPs stored at room temperature for 30 d. Figure 12C depicts a photograph of AuNPs stored for 30 d at room temperature prior to autoclaving. Figure 12D depicts a photograph of AuNPs stored for 30 d at room temperature post-autoclaving. Figure 13, comprising Figure 13A through Figure 13J, depicts stability testing of oleate bilayer capped gold nanoparticles in growth media. Figure 13A depicts a UV-Vis spectrum in DMEM. Figure 13B depicts a UV-Vis spectrum in OptiMEM. Figure 13C depicts a UV-Vis spectrum in 1% bovine serum albumin (BSA). Figure 13D depicts a UV-Vis spectrum in complete DMEM. Figure 13E depicts a UV-Vis spectrum in complete RPMI. Figure 13F depicts a photograph of the nanoparticles in in DMEM. Figure 13G depicts a photograph of the nanoparticles in in OptiMEM. Figure 13H depicts a photograph of the nanoparticles in in 1% bovine serum albumin (BSA). Figure 13I depicts a photograph of the nanoparticles in in complete DMEM. Figure 13J depicts a photograph of the nanoparticles in in complete RPMI. Figure 14, comprising Figure 14A and Figure 14B, depicts NaOl / OA self- assembly changes throughout the oleate mediated AuNP synthesis and bilayer coating Laurdan. Figure 14A depicts the photoluminescence peak shift evaluated in a temperature-controlled, stirred single cell setup, triplicate experiments. Figure 14B depicts multiplexed monitoring using plate reader fluorescence filter bands, 9-fold multiplicates (9 wells per oleate / Au-precursor ratio). Figure 15, comprising Figure 15A through Figure 15C, depicts representative characterization data of gold nanoseeds. Figure 15A depicts a representative TEM micrograph of Attorney Docket No.: 047162-5361-00WO gold nanoseeds. Figure 15B depicts a picture of gold nanoseeds in water. Figure 15C depicts a UV-Vis near-infrared (NIR) spectrum of gold nanoseeds. Figure 16, comprising Figure 16A through Figure 16C, depicts representative characterization data of platinum nanoparticles. Figure 16A depicts a representative TEM of platinum nanoparticles. Figure 16B depicts a representative energy dispersive x-ray (EDX) spectrum (sample prepared on lacey carbon copper grid). Figure 16C depicts EDX mapping. Figure 17, comprising Figure 17A through Figure 17E, depicts representative characterization data of platinum-gold nanoparticles. Figure 17A depicts a photo of platinum- gold nanoparticles in entries 29-32 of Example 2 from left to right. Figure 17B depicts low magnification EDX mapping of table entry 29 of Example 2. Figure 17C depicts a TEM of table entry 29 of Example 2. Figure 17D depicts an EDX spectrum of table entry 29 of Example 2 (sample prepared on lacey carbon copper grid). Figure 17E depicts high magnification EDX mapping of table entry 29 of Example 2. DETAILED DESCRIPTION Definitions Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As used herein, each of the following terms has the meaning associated with it in this section. 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. “About” as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of ±20%, ±10%, ±5%, ±1%, or ±0.1% from the specified value, as such variations are appropriate to perform the disclosed methods. As used herein, the term “nanoparticle” refers to particles having a particle size on the nanometer scale (e.g., about 1 nm – 10,000 nm). For example, the nanoparticle may have a particle size up to about 2,000 nm. In another example, the nanoparticle may have a particle size Attorney Docket No.: 047162-5361-00WO up to about 100 nm. In another example, the nanoparticle may have a particle size up to about 6 nm. As used herein, “nanoparticle” refers to a number of nanoparticles, including, but not limited to, liposomes, lipid nanoparticles, polymer nanoparticles, organic nanoparticles, inorganic nanoparticles, biocompatible nanoparticles, such as biocompatible organic nanoparticles, biocompatible inorganic nanoparticles, etc., nanoclusters, nanocapsules, core-shell nanocapsules, nanovesicles, micelles, block copolymer micelles, lamaellae shaped particles, polymersomes, dendrimers, emulsions, exosomes, self-emulsifying drug delivery systems (SEDDS), microspheres, micro-structured lipid carriers, nano-structured lipid carriers, and other nano-size particles of various other small fabrications that are known to those of skill in the art. Examples of suitable nanoparticles useful in the invention include, but are not limited to, those described in Wang et al., 2014, J. Nutri. Biochem., 25:363-376, which is incorporated herein by reference in its entirety. The shapes and compositions of nanoparticles may be guided during condensation of atoms by selectively favoring growth of particular crystal facets to produce spheres, rods, wires, discs, cages, core-shell structures and many other shapes. The definitions and understandings of the entities falling within the scope of nanocapsule are known to those of skill in the art, and such definitions are incorporated herein by reference and for the purposes of understanding the general nature of the subject matter of the present application. However, the following discussion is useful as a further understanding of some of these terms. The term “emulsion” as used herein refers to a mixture of two or more substances, such as liquids, that are normally immiscible, in which one substance forms droplets that are dispersed within another substance. One substance (the dispersed phase) is dispersed in the other (the continuous phase). Depending on the substances used, the droplets of an emulsion may be in the range of 1 nm to 100 μm, e.g., 1 nm to 100 nm, 1 μm to 50 μm, etc. For example, In some embodiments, the continuous phase is an aqueous phase and the dispersed phase is an organic (oily or hydrophobic) phase; that is, the emulsion is an oil-in-water emulsion. The terms “coat,” “coated,” or “coating,” as used herein, refer to at least a partial coating of the nanoparticle. One hundred percent coverage is not necessarily implied by these terms. As used herein, the term “pharmaceutically acceptable carrier” means a pharmaceutically acceptable material, composition or carrier, such as a liquid or solid filler, stabilizer, dispersing agent, suspending agent, diluent, excipient, thickening agent, solvent or Attorney Docket No.: 047162-5361-00WO encapsulating material, involved in carrying or transporting a compound useful within the invention within or to the subject such that it may perform its intended function. Typically, such constructs are carried or transported from one organ, or portion of the body, to another organ, or portion of the body. Each carrier must be “acceptable” in the sense of being compatible with the other ingredients of the formulation, including the compound useful within the invention, and not injurious to the subject. Some examples of materials that may serve as pharmaceutically acceptable carriers include: sugars, such as lactose, glucose, and sucrose; starches, such as corn starch and potato starch; cellulose, and its derivatives, such as sodium carboxymethyl cellulose, ethyl cellulose, and cellulose acetate; powdered tragacanth; malt; gelatin; talc; excipients, such as cocoa butter and suppository waxes; oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil, and soybean oil; glycols, such as propylene glycol; polyols, such as glycerin, sorbitol, mannitol, and polyethylene glycol; esters, such as ethyl oleate and ethyl laurate; agar; buffering agents, such as magnesium hydroxide and aluminum hydroxide; surface active agents; alginic acid; pyrogen-free water; isotonic saline; Ringer’s solution; ethyl alcohol; phosphate buffer solutions; and other non-toxic compatible substances employed in pharmaceutical formulations. As used herein, “pharmaceutically acceptable carrier” also includes any and all coatings, anti-bacterial and antifungal agents, and absorption delaying agents, and the like that are compatible with the activity of the compound useful within the invention, and are physiologically acceptable to the subject. Supplementary active compounds may also be incorporated into the compositions. The “pharmaceutically acceptable carrier” may further include a pharmaceutically acceptable salt of the compound useful within the invention. Other additional ingredients that may be included in the pharmaceutical compositions used in the practice of the invention are known in the art. The term “pharmaceutically acceptable salt” refers to any pharmaceutically acceptable salt, which upon administration to the subject is capable of providing (directly or indirectly) a compound as described herein. In some embodiments, such salts are acid addition salts with physiologically acceptable organic or inorganic acids. Examples of the acid addition salts include mineral acid addition salts such as, for example, hydrochloride, hydrobromide, hydroiodide, sulphate, nitrate, phosphate, and organic acid addition salts, such as, for example, acetate, trifluoroacetate, maleate, fumarate, citrate, oxalate, succinate, tartrate, malate, mandelate, methane sulphonate, and p-toluenesulphonate. Examples of the alkali addition salts Attorney Docket No.: 047162-5361-00WO include inorganic salts, such as, for example, sodium, potassium, calcium and ammonium salts, and organic alkali salts, such as, for example, ethylenediamine, ethanolamine, N,N- dialkylenethanolamine, triethanolamine, and basic amino acids salts. However, it will be appreciated that non-pharmaceutically acceptable salts also fall within the scope of the invention since those may be useful in the preparation of pharmaceutically acceptable salts. Procedures for salt formation are conventional in the art. The term “solvate” in accordance with this invention should be understood as meaning any form of the active compound in accordance with the invention in which the said compound is bonded by a non-covalent bond to another molecule (normally a polar solvent), including especially hydrates and alcoholates. Ranges: 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 the possible subranges 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 subranges 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. Description The present invention is based, in part, on the unexpected discovery that nanoparticles are readily synthesized in high concentrations using fatty acids. Thus, in one aspect, the present invention provides a method of synthesizing a nanoparticle. In another aspect, the present invention provides a nanoparticle synthesized using a method of the present invention. Methods of Making Nanoparticles The present invention relates, in part, to a method of synthesizing a nanoparticle, comprising the steps of: providing a metal solution comprising at least one metal precursor and at least one solvent; providing a fatty acid solution comprising at least one fatty acid and at least Attorney Docket No.: 047162-5361-00WO one solvent; combining the metal solution and the fatty acid solution to provide a combined solution; and collecting the nanoparticle from the combined solution. In some embodiments, the at least one metal precursor comprises an element selected from the group consisting of palladium, manganese, silver, gold, zinc, copper, iron, cobalt, nickel, platinum, sodium, any salts thereof, any hydrates thereof, any oxidation state thereof, and any combination thereof. Exemplary metal precursor include, but are not limited to, dimethyl zinc, diethyl zinc, zinc acetate, zinc acetylacetonate, zinc iodide, zinc bromide, zinc chloride, zinc fluoride, zinc carbonate, zinc cyanide, zinc nitrate, zinc oxide, zinc peroxide, zinc perchlorate, zinc sulfate, dimethyl cadmium, diethyl cadmium, cadmium acetate, cadmium acetylacetonate, cadmium iodide, cadmium bromide, cadmium chloride, cadmium fluoride, cadmium carbonate, cadmium nitrate, cadmium oxide, cadmium perchlorate, cadmium phosphide, cadmium sulfate, mercury acetate, mercury iodide, mercury bromide, mercury chloride, mercury fluoride, mercury cyanide, mercury nitrate, mercury oxide, mercury perchlorate, mercury sulfate, lead acetate, lead bromide, lead chloride, lead fluoride, lead oxide, lead perchlorate, lead nitrate, lead sulfate, lead carbonate, tin acetate, tin bisacetylacetonate, tin bromide, tin chloride, tin fluoride, tin oxide, tin sulfate, germanium tetrachloride, germanium oxide, germanium, ethoxide, gallium acetylacetonate, gallium chloride, gallium fluoride, gallium oxide, gallium nitrate, gallium sulfate, indium chloride, indium oxide, indium nitrate, indium sulfate, thallium acetate, thallium acetylacetonate, thallium chloride, thallium oxide, thallium ethoxide, thallium nitrate, thallium sulfate, thallium carbonate, scandium acetate, scandium chloride, scandium oxide, scandium nitrate, scandium sulfate, titanium chloride, titanium fluoride, titanium oxide, titanium isopropoxide, vanadium acetylacetonate, vanadium chloride, vanadium fluoride, vanadium oxide, chromium acetate, chromium acetylacetonate, chromium chloride, chromium fluoride, chromium oxide, chromium nitrate, chromium sulfate, manganese acetate, manganese acetylacetonate, manganese carbonate, manganese bromide, manganese chloride, manganese fluoride, manganese oxide, manganese sulfate, manganese perchlorate, iron acetate, iron acetylacetonate, iron bromide, iron chloride, iron fluoride, iron oxide, iron nitrate, iron sulfate, iron oxalate, iron perchlorate, cobalt acetate, cobalt acetylacetonate, cobalt bromide, cobalt chloride, cobalt fluoride, cobalt oxide, cobalt nitrate, cobalt sulfate, cobalt perchlorate, nickel acetate, nickel acetylacetonate, nickel bromide, nickel chloride, nickel oxide, nickel nitrate, nickel sulfate, nickel perchlorate, tetrakis(triphenylphosphite) nickel, copper acetate, Attorney Docket No.: 047162-5361-00WO copper acetylacetonate, copper bromide, copper chloride, copper fluoride, copper oxide, copper nitrate, copper sulfate, copper perchlorate, copper cyanide, yttrium acetate, yttrium chloride, yttrium fluoride, yttrium oxide, yttrium nitrate, yttrium sulfate, yttrium carbonate, yttrium isopropoxide, zirconium bromide, zirconium chloride, zirconium fluoride, zirconium oxide, zirconium butoxide, niobium chloride, niobium fluoride, niobium oxide, niobium ethoxide, molybdenum chloride, molybdenum oxide, palladium acetate, palladium acetylacetonate, palladium bromide, dichlorobis(triphenylphosphine)palladium, palladium chloride, palladium nitrate, palladium sulfate, palladium cyanide, silver bromide, silver chloride, silver fluoride, silver oxide, silver nitrate, silver sulfate, silver carbonate, silver cyanide, dichloro(ethylenediamine) platinum, dichlorobis(triphenyiphosphine)platinum, platinum acetylacetonate, platinum bromide, platinum chloride, platinum oxide, platinum nitrate, platinum cyanide, chloro (triphenylphosphine)gold, dimethyl(acetylacetonate)gold, gold bromide, gold chloride, gold oxide, gold cyanide, sodium tetrachloroplatinate, chloroplatinic acid, potassium tetrachloropalladate, and any hydrates thereof. There is no particular limit on the concentration of the metal precursor in the metal solution; any concentration that may be considered may be applicable to the present invention. In some embodiments, the metal solution has a metal precursor concentration of about 0.1 mM to about 50 mM. In some embodiments, the metal solution has a metal precursor concentration of about 0.1 mM to about 45 mM. In some embodiments, the metal solution has a metal precursor concentration of about 0.1 mM to about 40 mM. In some embodiments, the metal solution has a metal precursor concentration of about 0.1 mM to about 35 mM. In some embodiments, the metal solution has a metal precursor concentration of about 0.1 mM to about 30 mM. In some embodiments, the metal solution has a metal precursor concentration of about 0.1 mM to about 25 mM. In some embodiments, the metal solution has a metal precursor concentration of about 0.1 mM to about 20 mM. In some embodiments, the metal solution has a metal precursor concentration of about 0.1 mM to about 15 mM. In some embodiments, the metal solution has a metal precursor concentration of about 0.1 mM to about 10 mM. In some embodiments, the metal solution has a metal precursor concentration of about 0.1 mM to about 5 mM. In some embodiments, the metal solution has a metal precursor concentration of about 0.1 mM to about 1 mM. In some embodiments, the metal solution has a metal precursor concentration of about 1 mM to about 50 mM. In some embodiments, the metal solution has a Attorney Docket No.: 047162-5361-00WO metal precursor concentration of about 1 mM to about 45 mM. In some embodiments, the metal solution has a metal precursor concentration of about 1 mM to about 40 mM. In some embodiments, the metal solution has a metal precursor concentration of about 1 mM to about 35 mM. In some embodiments, the metal solution has a metal precursor concentration of about 1 mM to about 30 mM. In some embodiments, the metal solution has a metal precursor concentration of about 1 mM to about 25 mM. In some embodiments, the metal solution has a metal precursor concentration of about 1 mM to about 20 mM. In some embodiments, the metal solution has a metal precursor concentration of about 1 mM to about 15 mM. In some embodiments, the metal solution has a metal precursor concentration of about 1 mM to about 10 mM. In some embodiments, the metal solution has a metal precursor concentration of about 1 mM to about 5 mM. In some embodiments, the metal solution has a metal precursor concentration of about 5 mM to about 50 mM. In some embodiments, the metal solution has a metal precursor concentration of about 5 mM to about 45 mM. In some embodiments, the metal solution has a metal precursor concentration of about 5 mM to about 40 mM. In some embodiments, the metal solution has a metal precursor concentration of about 5 mM to about 35 mM. In some embodiments, the metal solution has a metal precursor concentration of about 5 mM to about 30 mM. In some embodiments, the metal solution has a metal precursor concentration of about 5 mM to about 25 mM. In some embodiments, the metal solution has a metal precursor concentration of about 5 mM to about 20 mM. In some embodiments, the metal solution has a metal precursor concentration of about 5 mM to about 15 mM. In some embodiments, the metal solution has a metal precursor concentration of about 5 mM to about 10 mM. In some embodiments, the metal solution has a metal precursor concentration of at least about 0.1 mM, 1 mM, 5 mM, 10 mM, 15 mM, 20 mM, 25 mM, 30 mM, 35 mM, 40 mM, 45 mM, or 50 mM. In some embodiments, the at least one solvent is aqueous. In some embodiments, the at least one solvent is inorganic. In some embodiments, the at least one solvent is organic. Exemplary solvents include, but are not limited to, water, distilled water, MilliQ water, ammonia, alkanes, acetone, ethanol, acetonitrile, ethyl acetate, ether, benzene, toluene, dimethylsulfoxide, chloroform, butanol, tetrachloroethylene, xylenes, and combinations thereof. In some embodiments, the at least one fatty acid is selected from the group consisting of oleic acid, palmitoleic acid, linoleic acid, palmitic acid, lauric acid, vaccenic acid Attorney Docket No.: 047162-5361-00WO paullinic acid, elaidic acid, gondoic acid, erucic acid, nervonic acid, mead acid, myristic acid, salts thereof, and esters thereof. In some embodiments, the fatty acid solution further comprises a salt of the at least one fatty acid. For example, the fatty acid solution further comprises sodium oleate. There is no particular limit on the concentration of the fatty acid; any concentration that may be considered may be applicable to the present invention. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 300 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 290 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 280 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 270 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 260 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 250 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 240 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 230 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 220 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 210 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 200 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 190 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 180 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 170 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 160 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 150 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 140 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 130 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 120 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 110 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 100 mM. In some embodiments, the fatty acid solution Attorney Docket No.: 047162-5361-00WO has a fatty acid concentration of about 30 mM to about 90 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 80 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 70 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 60 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 30 mM to about 50 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 300 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 290 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 280 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 270 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 260 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 250 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 240 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 230 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 220 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 210 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 200 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 190 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 180 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 170 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 160 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 150 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 140 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 130 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 120 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 110 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 100 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 90 Attorney Docket No.: 047162-5361-00WO mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 80 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 70 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 60 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 40 mM to about 50 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 300 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 290 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 280 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 270 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 260 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 250 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 240 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 230 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 220 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 210 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 200 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 190 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 180 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 170 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 160 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 150 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 140 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 130 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 120 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of about 100 mM to about 110 mM. In some embodiments, the fatty acid solution has a fatty acid concentration of at least about 10 mM, 20 mM, 30 mM, 40 mM, 50 mM, 60 mM, 70 mM, 80 mM, 90 mM, 100 mM, 110 mM, 120 mM, 130 mM, 140 mM, Attorney Docket No.: 047162-5361-00WO 150 mM, 160 mM, 170 mM, 180 mM, 190 mM, 200 mM, 210 mM, 220 mM, 230 mM, 240 mM, 250 mM, 260 mM, 270 mM, 280 mM, 290 mM, or 300 mM. There is no particular limit on the concentration of the nanoparticle; any concentration that may be considered may be applicable to the present invention. In some embodiments, the concentration of the nanoparticle is less than 1 mM. In some embodiments, the concentration of the nanoparticle is greater than 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 1 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 2 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 3 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 4 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 5 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 6 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 7 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 8 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 9 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 10 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 11 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 12 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 13 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 14 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 15 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 16 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 17 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 18 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is about 19 mM to about 20 mM. In some embodiments, the concentration of the nanoparticle in the combined solution is at least about 1 Attorney Docket No.: 047162-5361-00WO mM, 2 mM, 3 mM, 4 mM, 5 mM, 6 mM, 7 mM, 8 mM, 9 mM, 10 mM, 11 mM, 12 mM, 13 mM, 14 mM, 15 mM, 16 mM, 17 mM, 18 mM, 19 mM, or 20 mM. In some embodiments, the step of providing a fatty acid solution further comprises the step of heating the fatty acid solution. In some embodiments, the method further comprises the step of heating the combined solution. In some embodiments, the step of heating is performed using a thermocycler. In some embodiments, the step of heating is performed using a hot plate. In some embodiments, the step of heating is performed in a dry bath. In some embodiments, the heating is performed in a block heater. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 100 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 95 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 90 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 85 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 80 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 75 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 70 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 65 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 60 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 55 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 50 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 45 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between about 30 °C to about 40 °C. In some embodiments, the step of heating comprises heating the solution to a final temperature between at least about 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, or 100 °C. Attorney Docket No.: 047162-5361-00WO In some embodiments, the step of heating comprises heating the solution for about 1 minute to about 100 hours. In some embodiments, the step of heating comprises heating the solution for about 5 minutes to about 100 hours. In some embodiments, the step of heating comprises heating the solution for about 15 minutes to about 100 hours. In some embodiments, the step of heating comprises heating the solution for about 25 minutes to about 100 hours. In some embodiments, the step of heating comprises heating the solution for about 35 minutes to about 100 hours. In some embodiments, the step of heating comprises heating the solution for about 45 minutes to about 100 hours. In some embodiments, the step of heating comprises heating the solution for about 55 minutes to about 100 hours. In some embodiments, the step of heating comprises heating the solution for about 1 hour to about 100 hours. In some embodiments, the step of heating comprises heating the solution for about 1 hour to about 90 hours. In some embodiments, the step of heating comprises heating the solution for about 1 hour to about 80 hours. In some embodiments, the step of heating comprises heating the solution for about 1 hour to about 70 hours. In some embodiments, the step of heating comprises heating the solution for about 1 hour to about 60 hours. In some embodiments, the step of heating comprises heating the solution for about 1 hour to about 50 hours. In some embodiments, the step of heating comprises heating the solution for about 1 hour to about 40 hours. In some embodiments, the step of heating comprises heating the solution for about 1 hour to about 30 hours. In some embodiments, the step of heating comprises heating the solution for about 1 hour to about 20 hours. In some embodiments, the step of heating comprises heating the solution for about 5 hours to about 100 hours. In some embodiments, the step of heating comprises heating the solution for about 10 hours to about 90 hours. In some embodiments, the step of heating comprises heating the solution for about 15 hours to about 80 hours. In some embodiments, the step of heating comprises heating the solution for about 20 hours to about 70 hours. In some embodiments, the step of heating comprises heating the solution for about 25 hours to about 100 hours. In some embodiments, the step of heating comprises heating the solution for about 30 hours to about 90 hours. In some embodiments, the step of heating comprises heating the solution for about 35 hours to about 80 hours. In some embodiments, the step of heating comprises heating the solution for about 40 hours to about 70 hours. In some embodiments, the step of heating comprises heating the solution for about 45 hours to about 100 hours. In some embodiments, the step of heating comprises heating the solution for about 50 hours to about 90 hours. In some Attorney Docket No.: 047162-5361-00WO embodiments, the step of heating comprises heating the solution for about 65 hours to about 80 hours. In some embodiments, the step of heating comprises heating the solution for about 65 hours to about 70 hours. In some embodiments, the step of heating comprises heating the solution for at least about 1 minute, 5 minutes, 15 minutes, 25 minutes, 35 minutes, 45 minutes, 55 minutes, 1 hour, 5 hours, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, 80 hours, 90 hours, or 100 hours. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 1:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 2:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 3:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 4:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 5:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 6:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 7:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 8:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 9:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 10:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 11:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 12:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 13:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 14:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 15:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 16:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 17:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 18:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 19:1 to about 30:1. In some embodiments, the Attorney Docket No.: 047162-5361-00WO ratio of the at least one fatty acid to the at least one metal precursor is about 20:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 21:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 22:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 23:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 24:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 25:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 26:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 27:1 to about 30:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 1:1 to about 9:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 2:1 to about 9:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 3:1 to about 9:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 4:1 to about 9:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 5:1 to about 9:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 6:1 to about 9:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 7:1 to about 9:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 8:1 to about 9:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is about 8:1 to about 10:1. In some embodiments, the ratio of the at least one fatty acid to the at least one metal precursor is at least about 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, 21:1, 22:1, 23:1, 24:1, 25:1, 26:1, 27:1, 28:1, 29:1, or 30:1. In some embodiments, the step of collecting the nanoparticle from the combined solution comprises the step of centrifuging the combined solution to provide a centrifuged solution. In some embodiments, the step of collecting the nanoparticle comprises the step of removing the supernatant from the centrifuged solution to provide the nanoparticle. In some embodiments, the step of collecting the nanoparticle comprises the step of washing the nanoparticle with solution at least one time. In some embodiments, the nanoparticle is washed Attorney Docket No.: 047162-5361-00WO with aqueous solution. In some embodiments, the nanoparticle is washed with organic solution. In some embodiments, the nanoparticle is purified using dialysis cassettes. In some embodiments, the nanoparticle is purified at a pH of about 9. In some embodiments, the nanoparticle is purified using 10 kDA dialysis cassettes. In some embodiments, the nanoparticle solution is purified in a solution comprising water. In some embodiments, the method further comprises the step of combining the nanoparticle with a capping agent. In some embodiments, the capping agent comprises at least one functionality selected from the group consisting of a thiol, polyethylene glycol (PEG), and a fluorescein dye. Exemplary capping agents include, but are not limited to, fluorescein- polyethylene glycol-thiol (FITC-PEG-SH), lipoid acid, and glutathione. In some embodiments, the method is automated. Compositions and Nanoparticles The present invention also relates to, in part, a nanoparticle synthesized using the method disclosed herein. In some embodiments, the nanoparticle has a diameter of about 5 nm to about 50 nm. In some embodiments, the nanoparticle has a diameter of about 5 nm to about 45 nm. In some embodiments, the nanoparticle has a diameter of about 5 nm to about 40 nm. In some embodiments, the nanoparticle has a diameter of about 5 nm to about 35 nm. In some embodiments, the nanoparticle has a diameter of about 5 nm to about 30 nm. In some embodiments, the nanoparticle has a diameter of about 5 nm to about 25 nm. In some embodiments, the nanoparticle has a diameter of about 5 nm to about 20 nm. In some embodiments, the nanoparticle has a diameter of about 5 nm to about 15 nm. In some embodiments, the nanoparticle has a diameter of about 5 nm to about 10 nm. In some embodiments, the nanoparticle has a diameter of about 10 nm to about 40 nm. In some embodiments, the nanoparticle has a diameter of about 10 nm to about 35 nm. In some embodiments, the nanoparticle has a diameter of about 10 nm to about 30 nm. In some embodiments, the nanoparticle has a diameter of about 10 nm to about 25 nm. In some embodiments, the nanoparticle has a diameter of about 10 nm to about 20 nm. In some embodiments, the nanoparticle has a diameter of about 10 nm to about 15 nm. In some Attorney Docket No.: 047162-5361-00WO embodiments, the nanoparticle has a diameter of at least about 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, or 50 nm. In various embodiments, the nanoparticle has an average hydrodynamic diameter of from about 10 nm to about 10,000 nm, from about 130 nm to about 2,500 nm, from about 50 nm to about 150 nm, from about 60 nm to about 130 nm, from about 70 nm to about 110 nm, from about 70 nm to about 100 nm, from about 80 nm to about 100 nm, from about 90 nm to about 100 nm, from about 70 to about 90 nm, from about 80 nm to about 90 nm, from about 70 nm to about 80 nm, or about 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1,000 nm, 2,000 nm, 2,500 nm, 5,000 nm, or 10,000 nm. For example, in various embodiments, the nanoparticle has an average particle size (e.g., average hydrodynamic diameter of the nanoparticle) below about 2,500 nm. In some embodiments, the nanoparticle has a particle size (e.g., average hydrodynamic diameter of the nanoparticle) of between about 1 nm to about 2,500 nm. In some embodiments, the nanoparticle has a particle size (e.g., average hydrodynamic diameter of the nanoparticle) of between about 1 nm to about 300 nm. In some embodiments, the nanoparticle has a particle size (e.g., average hydrodynamic diameter of the nanoparticle) of between about 1 nm to about 200 nm. In some embodiments, the nanoparticle of the present invention is substantially non-toxic. In some embodiments, the nanoparticle of the present invention is biocompatible. In various embodiments, the nanoparticle or composition further comprises at least one coating agent. In some embodiments, the coating agent coats the outside surface of the nanoparticle. In some embodiments, the coating agent coats a portion of the outside surface of the nanoparticle. In some embodiments, the coating agent comprises a chitosan, starch, stabilizer, plasticizer, lipid, polysaccharide, protein, zein, soy protein, whey, casein, fatty acid, wax, neutral lipid, resin, cellulose, methyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, alginate, or any combination thereof. For example, in some embodiments, the nanoparticle is coated with chitosan, methyl cellulose, hydroxypropyl methyl cellulose, or any combination thereof. In some embodiments, the coating agent comprises a biocompatible polymer. Examples of coating agents include, but are not limited to, biocompatible polymer, a biodegradable polymer, a multifunctional linker, starch, modified starch, and starch derivatives, gums, including but not limited to polymers, polypeptides, albumin, amino acids, alcohols (e.g., Attorney Docket No.: 047162-5361-00WO PVA, ethyl alcohol, etc.), thiols, amines, carboxylic acid and combinations or derivatives thereof, citric acid, xanthan gum, alginic acid, other alginates, benitoniite, veegum, agar, guar, locust bean gum, gum arabic, quince psyllium, flax seed, okra gum, arabinoglactin, pectin, tragacanth, scleroglucan, dextran, amylose, amylopectin, dextrin, etc., cross-linked polyvinylpyrrolidone, ion-exchange resins, potassium polymethacrylate, carrageenan (and derivatives), gum karaya and biosynthetic gum, polycarbonates (linear polyesters of carbonic acid); microporous materials (bisphenol, a microporous poly(vinylchloride), micro-porous polyamides, microporous modacrylic copolymers, microporous styrene-acrylic and its copolymers); porous polysulfones, halogenated poly(vinylidene), polychloroethers, acetal polymers, polyesters prepared by esterification of a dicarboxylic acid or anhydride with an alkylene polyol, poly(alkylenesulfides), phenolics, polyesters, asymmetric porous polymers, cross-linked olefin polymers, hydrophilic microporous homopolymers, copolymers or interpolymers having a reduced bulk density, and other similar materials, poly(urethane), cross- linked chain-extended poly(urethane), poly(imides), poly(benzimidazoles), collodion, regenerated proteins, semi-solid cross-linked poly(vinylpyrrolidone), monomeric, dimeric, oligomeric or long-chain, copolymers, block polymers, block co-polymers, polymers, PEG, dextran, modified dextran, polyvinylalcohol, polyvinylpyrollidone, polyacrylates, polymethacrylates, polyanhydrides, polypeptides, albumin, alginates, amino acids, thiols, amines, carboxylic acids, phospholipids, albumin, dextran, gelatin, poly(ethylene glycerol) (PEG), poly(vinylpyrrolidone), hyaluronic acid, heparin, heparin sulfate, sialic acid, poly(N- acetylglucosamine) (Chitin), Chitosan, poly(3-hydroxyvalerate), poly(D,L-lactide-co-glycolide), poly(1-lactide-co-glycolide), poly(3-hydroxybutyrate), poly(4-hydroxybutyrate), poly(3- hydroxybutyrate-co-3-hydroxyvalerate), polyorthoester, polyanhydride, poly(glycolic acid), poly(glycolide), poly(L-lactic acid), poly(L-lactide), poly(D,L-lactic acid), poly(D,L-lactide), poly(L-lactide-co-D,L-lactide), poly(caprolactone), poly(L-lactide-co-caprolactone), poly(D,L- lactide-co-caprolactone), poly(glycolide-co-caprolactone), poly(trimethylene carbonate), polyester amide, poly(glycolic acid-co-trimethylene carbonate), co-poly(ether-esters) (e.g. PEO / PLA), polyphosphazenes, fibrin, fibrin glue, fibrinogen, cellulose, starch, collagen and hyaluronic acid, elastin and hyaluronic acid, polyurethanes, silicones, polyesters, polyolefins, polyisobutylene and ethylene-alphaolefin copolymers, acrylic polymers and copolymers other than polyacrylates, vinyl halide polymers and copolymers, polyvinyl chloride, polyvinyl ethers, Attorney Docket No.: 047162-5361-00WO polyvinyl methyl ether, polyvinylidene halides, polyvinylidene chloride, poly(vinylidene fluoride), poly(vinylidene fluoride-co-hexafluoropropylene), polyacrylonitrile, polyvinyl ketones, polyvinyl aromatics, polystyrene, polyvinyl esters, polyvinyl acetate, acrylonitrile- styrene copolymers, ABS resins, polyamides, Nylon 66, polycaprolactam, polycarbonates including tyrosine-based polycarbonates, polyoxymethylenes, polyimides, polyethers, polyurethanes, rayon, rayon-triacetate, cellulose, cellulose acetate, cellulose butyrate, cellulose acetate butyrate, cellophane, cellulose nitrate, cellulose propionate, cellulose ethers, carboxymethyl cellulose, fullerenes, lipids, or any combination thereof. In some embodiments, the nanoparticle is any type of nanoparticle, including, but not limited to, liposomes, lipid nanoparticles, organic nanoparticles, inorganic nanoparticles (e.g., metal nanoparticles, such as gold nanoparticles, iron nanoparticles, ZnO nanoparticles, TiO2 nanoparticles, etc.), biocompatible nanoparticles, such as biocompatible organic nanoparticles, biocompatible inorganic nanoparticles, etc., polymer nanoparticles, nanoclusters, nanocapsules, core-shell nanocapsules, nanovesicles, micelles, block copolymer micelles, lamaellae shaped particles, polymersomes, dendrimers, emulsions, exosomes, SEDDS, microspheres, micro-structured lipid carriers, nano-structured lipid carriers, and other nano-size particles of various other small fabrications that are known to those of skill in the art. Nanoparticle Compositions The present invention also relates to, in part, a composition comprising a nanoparticle synthesized using the method disclosed herein. In some embodiments, the composition is a suspension. In some embodiments, the composition further comprises a solvent. Exemplary solvents include, but are not limited to, Dulbecco’s Modified Eagle Medium (DMEM), Roswell Park Memorial Institute (RPMI) medium, and Minimum Essential Medium (MEM). In some embodiments, the solvent has a pH of about 1.0 to about 14.0. In some embodiments, the solvent has a pH of about 7.0 to about 8.0. In some embodiments, the solvent has a pH of about 7.1 to about 8.0. In some embodiments, the solvent has a pH of about 7.2 to about 8.0. In some embodiments, the solvent has a pH of about 7.3 to about 8.0. In some embodiments, the solvent has a pH of about 7.4 to about 8.0. In some embodiments, the solvent has a pH of about 7.5 to about 8.0. In some embodiments, the solvent has a pH of about 7.6 to Attorney Docket No.: 047162-5361-00WO about 8.0. In some embodiments, the solvent has a pH of about 7.7 to about 8.0. In some embodiments, the solvent has a pH of about 7.8 to about 8.0. In some embodiments, the solvent has a pH of about 7.9 to about 8.0. In some embodiments, the solvent has a pH of at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14. EXPERIMENTAL EXAMPLES 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. 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 present invention and practice the claimed methods. The following working examples therefore are not to be construed as limiting in any way the remainder of the disclosure. Example 1: Multiplexable and Scalable Aqueous Synthesis Platform for Oleate-Based, Bilayer- Coated Gold Nanoparticles Further applications continue to be developed using gold nanoparticles for medicinal therapies (Mao et al., 2020, Nanoscale, 12, 14996; Fan et al., 2021, Nature Communications, 12; Goldberg, 2019, Nature Reviews Cancer, 19, 587), imaging (Bouche et al., 2020, Bioconjugate Chemistry, 31, 303), environmental sensing (Cho et al., 2023, ACS Applied Materials & Interfaces, 15, 19785), electronics (Tan et al., 2019, Advanced Electronic Materials, 5, 1800831), and catalysis (Chen et al., 2021, Journal of the American Chemical Society, 143, 5727). However, practical limitations with respect to large-scale synthesis, reproducibility, size control, and sensitive reaction systems result in either the need for specialized synthesis laboratory skillsets, a low-throughput characterization, and / or extensive post-synthesis purification and size sorting. Taken together, such factors lead to high prices for commercially available gold nanoparticles (USD 10-200 per mg; 30 to 500-fold margin as compared to the precursor). Statements on gold nanoparticle prices are based on comparison of mass-normalized Attorney Docket No.: 047162-5361-00WO prices when purchasing the larges pack size (most Au in nanoparticle form by mass in a single product packaging) from the suppliers listed below. Normalized Source Product Pack size Size CV Capping Price Price Number (nm) agent (USD) (USD / mg Au) 20 Cytodiagnostics G-20-1000- 530 mg 20 <12% Citrate + 10,750.00 Inc. 10 (1000ml@ PBS 0.1 0.53 mg mM Au / ml) 119 Nanocomposix AUCB10- 30 mg (30 20 ≤ Citrate 3560 30M ml@1 mg 15% Au / ml) 22 Nanocomposix AUCN20- 53 mg (1000 20 ≤ Citrate 1L ml@0.053 mg 15% 1145 Au / ml) 7.5 Nanopartz 20-CIT- 530 mg 20 <12% Citrate 4000 DIH-1- (10000 10000 ml@0.053 mg Au / ml) 61 Thermo Fisher J67370.AE 5.3 mg (100 20 10% Reactant 324 ml@0.053 mg free in 0.1 Au / ml) mM PBS The most widely used and best documented method for gold nanoparticle synthesis, Turkevich-Frens method (Wuithschick et al., 2015, ACS Nano, 9, 7052), was developed in the middle of the last century and utilizes citrate as a reducing and capping agent. Since its inception, notable advances in synthetic control and insights into the particle growth model have been documented and continue to be refined (Kettemann et al., 2016, Chemistry of Materials, 28, 4072; Schultz et al., 2014, Langmuir, 30, 10779; Kimling et al., 2006, The Journal of Physical Chemistry B, 110, 15700; Chen et al., 2021, The Journal of Physical Chemistry C, 125, 1087). Continuous improvements such citrate-based methods have led to precise size control, low size variation and straightforward capping agent exchange (Larm et al., 2018, The Journal of Physical Chemistry C, 122, 5105, Piella et al., 2016, Chemistry of Materials, 28, 1066). However, most syntheses proceed at low concentrations only, hampering scalability, or require growth moderating surfactants with limited biocompatibility. Promising approaches for (self)optimizing gold nanoparticle syntheses leverage multiplexing and flow chemistry developed in synthetic biology and the pharmaceutical industry (Zhao et al., 2023, Nature Synthesis; Damilos et al., 2021, Journal of Flow Chemistry; Bianchi et al., 2020, Reaction Chemistry & Engineering, 5, 1224; Salley et al., 2020, Nature Communications, 11; Volk et al., Attorney Docket No.: 047162-5361-00WO 2023, Nature Communications, 14). In particular, several adaptations of existing citrate-based syntheses have been reported for gold nanoparticle (AuNP) synthesis, incorporating multiplexing and / or continuous flow. For these, flow reactor fouling and special cooling requirements for multiplexing workflows are common limitations (Besenhard et al., 2023, Reaction Chemistry & Engineering, 8, 955). For gold nanoparticle preparation, several adaptations of existing syntheses have been demonstrated using multiplexing and / or flow conditions, although coming along with limitations, such as flow reactor fouling, or cumbersome cooling requirements for multiplexing workflows to limit precocious nanoparticle growth. Inspired by the popular synthesis of metal oxide nanoparticles in the presence of fatty acids at gram scale and higher with size control of <5% variation, and improved mechanistic understanding (Park et al., 2004, Nature Materials, 3, 891; Lassenberger et al., 2017, Chemistry of Materials, 29, 4511; Chang et al., 2019, Journal of the American Chemical Society, 141, 7037) combined with the well-studied behavior of oleic acid as a capping agent with lipid bilayer forming capability in aqueous systems for several classes of metal oxide nanoparticles and quantum dots (Cass et al., 2013, Analytical Chemistry, 85, 6974; Schroter et al., 2023, Angewandte Chemie International Edition, 62; Gee et al., 2020, The Journal of Physical Chemistry C, 124, 23964), a method for size-controlled synthesis gold nanoparticles in the aqueous sodium oleate / oleic acid (NaOl / OA) phase system was developed. Oleic acid bilayer coating provides a cost effective particle protection for use in nanocomposites (Dreyer et al., 2016, Nature Materials, 15, 522; He et al., 2010, Small, 6, 1449), or biological systems, including further functionalization (Lee et al., 2013, Journal of the American Chemical Society, 135, 5950; Guo et al., 2016, Science Advances, 2, e1600261; Mitchell et al., 2021, Drug Discovery, 20, 101, Blanco et al., 2015, Nature Biotechnology, 33, 941). This endeavor was supported by several reports on the growth and assembly of nanoparticles (NPs) on OA interfaces (Lopez-De-Luzuriaga et al., 2021, Nanoscale Advances, 3, 198; Shin et al., 2015, Scientific Reports, 4, 6119; Shin et al., 2018, Advanced Materials Interfaces, 5, 1800981; Fujita et al., 2016, Physical Chemistry Chemical Physics, 18, 5464), as well as the common use oleic acid as an auxiliary surfactant in shape-controlled gold nanoparticle growth (Ye et al., 2013, Nano Letters, 13, 2163). However, the requirements for low concentration (Yue et al., 2023, iScience, 26, 105864), and oftentimes complex micro reaction environments (Lee et al., 2016, Attorney Docket No.: 047162-5361-00WO Science Advances, 2, e1601838), illustrate the remaining challenge of a simple route to bilayer capped gold nanoparticles at practical scale. Despite gold-based nanomaterials having a unique role in nanomedicine, among other fields, synthesis limitations relating to reaction scale-up and control result in prohibitively high gold nanoparticle costs. In this work, a new preparation procedure for lipid bilayer-coated gold nanoparticles in water is presented, using sodium oleate as reductant and capping agent. The seed-free synthesis not only allows for size precision (8-30 nm) but also remarkable particle concentration (10 mM Au). These reaction efficiencies allow for multiplexing and reaction standardization in 96-well plates using conventional thermocyclers, in addition to simple particle-purification via microcentrifugation. Such an (multiplexing) approach also enables detailed spectroscopic investigation of the nonlinear growth process and dynamic sodium oleate / oleic acid self-assembly. In addition to scalability (at gram-level), resulting gold nanoparticles are stable at physiological pH, in common cell culture media (DMEM, RPMI), and are autoclavable. To demonstrate the versatility and applicability of the reported method, a robust ligand exchange with thiolated PEG-analogues is also presented. In this study, these challenges are addressed and important key advances in the state-of-the-art of AuNP synthesis are illustrated. Here, direct, unseeded synthesis route of bilayer coated AuNPs in water is demonstrated at a practical scale (2 mg AuNP / ml) and moderate temperatures (40-80ºC) by using high concentrations of Au-precursor (10 mM) and sodium oleate (45-270 mM), as a biocompatible reducing and capping agent. The resulting particle size distribution is comparable to conventional syntheses, achieving sizes from 8-30 nm in one single step, and featuring concentration increases of up to 40-times compared to the optimized inverted Turkevich method (Schultz et al., 2014, Langmuir, 30, 10779). A key advantage of the reported method is flexibility of multiplexing in a conventional thermocycler, providing standardized reaction environments at precisely controlled temperatures (±0.1ºC) and times, utilizing 96-well plates and PCR tubes as reaction vessels. Each 100 μl reaction can result in the equivalent of a 4 ml standard AuNP setup. This protocol is compatible with standard thermocycler liquid handing, and leads to a smaller product workup volume compared to citrate-based methods, enabling microcentrifugation-based purification workflows. Additionally, multiplexing allows for mechanistic insight into the particle formation and growth. Time resolved, temperature and pH-controlled multiplexed spectroscopy suggests Attorney Docket No.: 047162-5361-00WO growth via a multi-step process featuring: a) the complexation of gold ions with oleate at high pH, followed by b) a slow, temperature dependent nucleation (>5 min), and c) oleate bilayer encapsulation, before d) a steady precursor-complexation and supply limited growth stage. Following optimal reaction parameters, a significant scale up was demonstrated in a conventional glassware setup utilizing 0.5 g of Au, furnishing particle sizes comparable to the parent thermocycler setup (<5% mean size difference). Additionally, capping agent exchange was demonstrated with a thiolated PEG-derivative as model compound, indicating particle surface tunability. The experimental details and results of Example 2 are now described herein. Materials HAuCl4•3H2O (ACS reagent, ≥49.0% Au basis) was purchased from Sigma Aldrich, St. Louis, MO, USA. Sodium Oleate (>97%) was purchased from TCI, Tokyo, Japan. All experiments were conducted in MilliQ water (18.2 MΩ-cm, Millipak Express 20 polished). FITC-PEG-SH, 5k was purchased from Creative PEGworks, Durham, NC, USA. Cell culture media were prepared as follows: Dulbecco's Modified Eagle Medium 1X (DMEM 1X, CORNING 10-017-CV), Opti-MEM™ reduced-serum medium 1X (Gibco 31985-070), Roswell Park Memorial Institute medium (RPMI, Corning 10-040-CV) were used as supplied. DMEM and RPMI complete media were prepared by the addition of 10 vol% fetal bovine serum (Peak Serum, PS-FB4), 5 ml sodium pyruvate (Corning, 25-000-Cl), 5 ml Penicillin-Streptomycin 100X (Corning 45000-652), and 10 ml 1 M N-2- hydroxyethylpiperazine-N'-2-ethanesulphonic acid (HEPES 1M, Corning 25-060-CI) to 500 ml DMEM or RPMI base media. Bovine serum albumin (Sigma-Aldrich, ≥96% by agarose gel electrophoresis) solutions were prepared as 1 wt% in milliQ water. All growth media were stored at 4ºC, handled in biosafety cabinets to prevent contamination, and used within one week. Synthesis The sodium oleate / oleic acid mediated synthesis was carried out with volumetric mixtures of Au-precursor (100 mM HAuCl4•3H2O) in MilliQ water, and sodium oleate stock solutions (300 mM NaOl, MilliQ water) giving different overall gold to oleate ratios ranging from 27 / 1 to 3 / 1 (270 mM – 30 mM NaOl in the final reaction mixture). Attorney Docket No.: 047162-5361-00WO For upscaling experiments, glassware and stir bars were cleaned thoroughly with aqua regia and rinsed with water prior to synthesis. The sodium oleate / water mixture was heated up to the specified temperature under stirring prior to injection of the Au-solution. For multiplexing, whole reagent solutions were premixed through pipette blending to operate as close to an automatic liquid handler workflow as possible.100 μl of the mixed reagent solution was subsequently transferred into 96-well plates (Biorad white-shell, thin-wall, skirted) or domed-cap PCR tubes (Eppendorf 0.2ml, thin-walled Forensic DNA Grade PCR tubes). The 96-well palates were sealed with optical clear seal (Biorad Microseal B). Thermocycler synthesis was performed in a Biometra TGradient thermal cycler (Analytik Jena, Germany). During the synthesis runs, the thermocycler lid temperature was set to 105ºC to prevent evaporation while the heating block temperature was set to the desired synthesis temperature. A quick temperature ramp of 5 ºC per second was chosen. A cooling step to room temperature was implemented, initiating after the desired synthesis time at any given temperature was reached. For temperature-dependent screening, a maximum gradient across the thermocycler heating block of 40 ºC was chosen. Stock solutions of 300 mM sodium oleate in MilliQwater (approximately 90% of the solubility limit in water at room temperature) were prepared under stirring at 50 ºC and the solution was allowed to cool down to room temperature before use. Stock solutions of 100 mM in MilliQ water were prepared as follows. A vial was screw-cap vial with 15 ml MilliQ water before transfer into Nitrogen atmosphere. An unopened container containing 1 g tetrachloroauric acid trihydrate was used as received, weighed, transferred to Nitrogen atmosphere, and fully emptied into the water filled vial. The empty precursor container was weighed out afterwards and the transferred precursor amount was calculated based on this difference of full vs. empty vial. Then, the water content of the screw- cap vial was adjusted upwards to yield a stock solution of 100 mM gold precursor. Preparation of capping agent exchange and fluorescent probe solutions was performed as follows: A FITC-PEG-SH, 5k stock solution were prepared at 4.5 mg / ml in MilliQ water. Laurdan was prepared at mg / ml in spectroscopy-grade ethanol. All stock solutions were kept in a fridge and equilibrated to room temperature prior to use. Solutions were used up over the course of 3-5 days. Attorney Docket No.: 047162-5361-00WO In the thermocycler-based synthesis, using a 96-well plate, the formation of drying rings along the height of the reaction mixture liquid level at prolonged reaction times (longer than 24 h) was observed. The overall reaction mixture volume was consequently reduced to 100 μl, but successful synthesis were also achieved with limited solid deposit at the synthesis mixture liquid level for up to 150 μl. For domed-cap PCR tubes, a fill volume of 200 ul was possible without the formation of drying artifacts at the height of the reaction mixture level. Plates used for plate-reader based synthesis were Greiner Bio-One, black, medium binding f-bottom, uClear polystyrene microplates. The sealing film used was BioRad Microseal B Adhesive Sealer MSB-1001. Samples were purified at 20k rcf for 30 - 180 minutes (depending on expected particle size) in an Eppendorf 5242 microcentrifuge sample pelletizing. Purification was done in Eppendorf Safe-Lock 1.5 ml Forensic DNA Grade microcentrifuge tubes at 1ml fill volume. For each sample, 0.95-0.975 ml of the supernatant was discarded, and the particles were resuspended by sonication. If not stated otherwise, samples were washed three times. Capping agent exchange was performed as follows: 50 µl of dye or capping agent batch solution were added to 1 ml of triple washed oleate-synthesized gold nanoparticles diluted to OD5. The prepared solutions were sonicated for 10 min in a sonication bath and then incubated for 72 h at room temperature before triple washing by centrifugation. Synthesis scaleup was performed in a heated, temperature-controlled sand bath under standard atmosphere. The sand bath temperature was adjusted yield a stable target temperature measured inside the round bottom flask prior to gold precursor injection. Notably, glassware is easy to rinse post 24 h synthesis leaving little AuNP residues or hue on the glassware. Comparison to Peer-Reviewed Synthesis Scale-Up The synthesis disclosed herein is compared with the optimized inverted Turkevich protocol utilizing a citrate buffer and ethylenediaminetetraacetic acid (EDTA) which provided a well-documented synthesis scale-up to the liter scale, wherein a preheated (to 90-100 ºC) aqueous precursor solution of 0.8125 mM HAuCl4•3H2O was injected into a boiling 800ml solution of 2.75 mM solution 3 / 1 sodium citrate and citric acid (Schultz et al., 2014, Langmuir, 30, 10779). Attorney Docket No.: 047162-5361-00WO With the simplified assumption of a 100% yield and product recovery, this yields 1000 ml of 0.1625 mM AuNPs (0.8125mM x 200ml / (200ml + 1000ml)), the equivalent of 32 mg gold nanoparticles. For the thermocycler multiplexed synthesis, the following was obtained: 100 mM * 0.01 ml = 1 mM HAuCl4•3H2O per 100 μl well (0.197mg Au / well). One full 96-well plate at 100 μl fill level in every well equates to 590 ml of the optimized inverse Turkevich method reported by Schulz et al. When utilizing capped PCR tubes at 200 μl, one thermocycler run equates to about 1180 ml of a scaled-up Turkevich synthesis. The demonstrated scaled-up round bottom flask synthesis at 250 ml fill level yields a final gold concentration of 10 mM (493 mg Au), which would equal a 15 L synthesis of the optimized Turkevich method. Ligand exchange / dye functionalization Ligand exchange and dye functionalization was performed in microcentrifuge tubes. Vide supra synthesized and triple washed AuNPs were diluted to an approximate Au- concentration of 0.1 mg / ml. To 1 ml of diluted particles 50 μl of fluorescein PEG thiol, MW 5k (FITC-PEG-SH, 5k, 2 mg / ml in water) were added. The resulting mixtures were gently shaken and incubated in the dark at room temperature for 72 h, followed by three washing operations using microcentrifugation before analysis. Characterization Plate reader-based synthesis monitoring was performed on a temperature- controlled BioTek SynergyHT plate reader (Winooski, VT, USA) at 40 ºC. The amphiphilic probe Laurdan was purchased from Cayman Chemical, Ann Arbor, MI, USA. UV-Vis analysis was performed on a Cary 5000 UV-Vis-NIR spectrophotometer (Agilent Technologies, Santa Clara, CA, USA) in double beam mode using QX high precision quartz cuvettes with a 10 mm light path (Hellma Analytics, Germany). Temperature-controlled in-situ UV-Vis experiments were conducted on a UV-3600 plus spectrophotometer (Shimadzu, Japan) equipped with a S-1700 thermoelectric single cell holder and stirrer. A QS high precision cuvette with a 10mm light path (Hellma Analytics, Germany) was equipped with a 5 x 2 mm PTFE micro stir bar (Cole-Parmer, Vernon Hills, IL, USA). FTIR measurements were conducted on a Bruker Alpha II FTIR spectrometer. Functionalized nanoparticle samples were dried on the FTIR spectrometer crystal under Attorney Docket No.: 047162-5361-00WO atmosphere prior to analysis. At least 500 scans were collected for each sample at a spectral resolution of 4 cm-1. Transmission electron microscopy was performed on a FEI Tecnai Osiris 200 kV TEM (Hillsboro, OR, USA). All samples were drop cast (1 μl, stored on self-closing tweezers during drying) onto LC325-Cu-CC lacey carbon film grids (Electron Microscopy Sciences (Hatfield, PA, USA). Particle sizing via dynamic light scattering (DLS) was performed in a quartz DLS cuvette (Brookhaven Instruments BI-SCGO) on a NanoBrook Series Particle Analyzer (Brookhaven Instruments) under backscatter detection mode (173 °C). Transmission electron microscopy (TEM) grids were prepared by drop casting 1.5 µl of triple washed particles at approximate concentration of OD520= 4 on lacey carbon copper grids without further ligand modification or solvent transfer. Particle diameters were evaluated as Feret’s diameter (longest distance between any two points along the selection boundary) in Fiji / imageJ (Schindelin et al., 2012, Nature Methods, 9, 676). For anisotropic particles or micrographs with high particle density, particle outlining was performed manually. Outlines of counted particles and particle labels are shown in Figure 1. Photoluminescence measurements were performed by using Fluorolog®-3 spectrofluorometer with F-3030 temperature bath controller and a magnetic stirring system.250 µL of 300 mM Au precursor was added into the mixed and solution under stirring, which contained 2250 µL of 300 mM NaOl aqueous solution and 125 µL Laurdan in ethanol. The excitation wavelength was 366 nm. DLS Size Measurements AuNPs were characterized by DLS to measure the hydrodynamic diameter and zeta potential. The hydrodynamic diameters of both AuNPs for 27 / 1 and 9 / 1 synthesis ratio are shown below. It is of note that for the 9 / 1 bilayer coated AuNPs showed much larger than 27 / 1 AuNPs, which can be attributed by the higher anisotropy of the larger (9 / 1 synthesis ratio) AuNPs. Attorney Docket No.: 047162-5361-00WO Eff. Poly- Log- Log- Log- Log- Mean Mean Mean Mean Diam. dispersity normal normal normal normal Diam. Diam. Diam. Diam. (nm) Mean Mean Mean Mean By By By By Diam. Diam. Diam. Diam. Intensity Number Surface Volume By By By By Intensity Number Surface Volume (nm) (nm) (nm) (nm) Mean: 20.39 0.221 22.52 8.30 11.86 14.19 32.76 10.47 11.61 12.67 Std 0.12 0.007 0.09 0.33 0.30 0.26 1.38 0.55 0.47 0.37 Err: Std 0.55 0.034 0.42 1.49 1.35 1.18 6.16 2.47 2.10 1.66 Dev: DLS size measurement for 27 / 1 AuNPs Eff. Poly- Log- Log- Log- Log- Mean Mean Mean Mean Diam. dispersity normal normal normal normal Diam. Diam. Diam. Diam. (nm) Mean Mean Mean Mean By By By By Diam. Diam. Diam. Diam. Intensity Number Surface Volume By By By By Intensity Number Surface Volume (nm) (nm) (nm) (nm) Mean: 71.58 0.255 79.99 26.54 39.10 47.70 102.13 25.34 29.40 34.57 Std Err: 1.89 0.011 1.64 2.97 2.81 2.62 3.85 4.30 4.87 5.38 Std 8.45 0.050 7.33 13.30 12.56 11.70 17.22 19.23 21.78 24.07 Dev: DLS size measurements for 9 / 1 AuNPs Stability and Zeta Potential of Synthesized Gold Nanoparticles Colloidal stability of synthesized oleate bilayer coated AuNPs was tested for 30 minutes via DLS under exposure to high concentrations of phosphate-buffered saline (1x PBS). BL-AuNPs show higher stability at 1x PBS salt concentrations than commercialized citrate-capped AuNPs (NanoComposix NanoXact AUCN20) tested.27 / 1, 9 / 1 AuNPs, as well as citrate capped AuNPs are stable in low PBS concentrations (0.1 mM PBS, Figure 2A). Zeta potential for oleate bilayer coated AuNPs is in the range of -20 mV and -35 mV for AuNPs synthesized with oleate / Au-precursor ratios 27 / 1 and 9 / 1, respectively (Figure 2B, Figure 2C). Attorney Docket No.: 047162-5361-00WO Long term room temperature storage and autoclavability of NaOl bilayer-coated gold nanoparticles was evaluated.27 / 1 ratio AuNPs were stored at room temperature in a laboratory setting under laboratory light but protected from direct sunlight and autoclavability (20 min, steam autoclave) of fresh and 30-day stored AuNPs was evaluated. A blueshift of the LSPR peak of 519 nm to 515 nm for freshly prepared AuNP and 520 nm to 517 nm of 30-day stored nanoparticles was observed after autoclaving. Stability in Cell Growth Media Bilayer capped gold nanoparticles show intermediate stability in cell growth media. All liquid handling was performed in HEPA filtered laminar air flow. Samples were transferred to for UV-Vis measurement and discarded after measurement. A moderate aggregation can be observed after incubation for 72 h at 37 ºC and a slight aggregation after storage at 4 ºC for 72 h can be observed for DMEM complete and RPMI complete mixes, while particles show strong aggregation in OptiMEM suggesting the stabilization of BL-AuNPs by fetal bovine serum (Moore et al., 2015, Chem. Soc. Rev., 44, 6287). Time-Resolved Fluorometry The fluorescent probe Laurdan can be used to distinguish between micelle and bilayer-type self-assemblies of the aqueous NaOl / OA phase system (Suga et al., 2016, Langmuir, 32, 7606). Laurdan has been used in previous studies to investigate the interactions of nanoparticles with lipid membranes, where a shift in emission peaks at EM450 and EM520 is indicative of lipid self-assembly (vesicle-like form or a micellar form) (Kesner et al., 2023, Journal of the American Chemical Society, 145, 7962). Time-resolved, temperature-controlled photoluminescence measurements are indicative of a change towards a bilayer self-assembly in the reaction system. Adjusting the synthesis at the beginning of the synthesis with HCl to the same pH as measured directly after precursor injection in the 27 / 1 synthesis does not induce a peak shift over the course of 1 h (Figure 4G) indicating that the continuous peak shift is not induced by the initial pH adjustment of precursor injection. Multiplexed photoluminescence measurements in a plate reader are in support of the general spectroscopic trends observed, as well as the in-situ pH measurements (Figure 3B, Figure 4G, Figure 4H, Figure 5A through Figure 5C). Attorney Docket No.: 047162-5361-00WO The discussion of the experimental results of Example 2 are now described herein. Multiplexed Gold Nanoparticle Synthesis: Effect of Temperature and Sodium Oleate concentration on Particle Size AuNP size control of the NaOl / OA mediated synthesis was assessed through systematic variation of fatty acid concentration, reaction temperature, pH, and time. The effect of NaOl and temperature on particle size was evaluated in a thermocycler-based synthesis through mixing workflows that relied on pipetting only (Figure 6A). After 24 h of thermocycler-based heating, unseeded spherical gold nanoparticles with size control as a function of NaOl to Au- precursor ratio ranging 8-39 nm with a coefficient of variation (CV) of ±12-39% could be produced (Figure 1 and Figure 6A). After purification by triple washing, all obtained gold nanoparticle suspensions could be diluted to OD1, yielding gold nanoparticle suspensions with physiological pH values of 7.3-7.5. Obtaining 10 nm AuNPs at high concentrations with narrow size distributions (CV ≤ 12%, 27 / 1 NaOl / Au ratio) without mixing during the heating process for over 24 h is notable (Figure 6D). However, at lower NaOl concentrations (NaOl / Au ratios of 9 / 1 and below), CV as well as anisotropy increase drastically, and a low number of triangular-shaped particles can be observed (Figure 1, Figure 6D), similar to most unseeded citrate-based methods of AuNPs ≥ 15 nm. Furthermore, non-resuspendable aggregates were found to form at ratios of NaOl / Au precursor of 3 / 1 or lower (30 mM NaOl, 10mM HAuCl4). All obtained gold nanoparticle suspensions could be diluted to OD1 after purification. The tested temperature range of 40-80 ºC influences early particle growth (3 h), as well as final particle size and aggregation state (24 h) for synthesized AuNPs in the thermocycler-based system (Figure 6C). The influence of synthesis temperature was evaluated for NaOl to Au-precursor ratio 27 / 1 by TEM showing a temperature-dependent nonlinear evolution of particle size (6.9 – 9.9 nm) and particle size distribution (16.9 – 11.9%), with the narrowest particle size distribution at 70 ºC (Figure 6B, Figure 7). The influence of synthesis temperature in the thermocycler setup for the 27 / 1 ratio and a duration of 24 h was analyzed. While a general trend of increasing size with increasing Attorney Docket No.: 047162-5361-00WO temperature can be observed, the temperature influence on particle size is less pronounced in the tested range of 40 ºC – 80 ºC (∆size 40ºC,80ºC ≈ 3 nm, Figure 8) when compared to the oleate / Au- precursor range (∆size 27 / 1,4.1 / 1≈ 30 nm). Gram-Scale Synthesis of Sub-10 nm Gold Nanoparticles To verify the scalability of the high concentration reaction procedure, the highest overall NaOl concentration of 270 mM and Au-precursor concentration of 10 mM (NaOl / Au- precursor ratio 27 / 1) was used at a 0.5 g (Au), 250 ml scale, which corresponds to a 10 Liter synthesis with a standard Turkevich-Frens method (Figure 9). Both, thermocycler, and round bottom flask syntheses yielded spherical gold nanoparticles in similar size ranges for identical synthesis temperatures and NaOl / Au-precursor ratios (Figure 10). The scale-up reaction resulted in particle diameters of 8.6 nm (CV = 19%) in the round bottom flask, while the thermocycler- based synthesis yielded particle diameters of 8.5 nm. The slight difference in size can be attributed to the change in reaction system (different heat transfer and stirred scale-up vs. non- stirred thermocycler-based synthesis). It is of note that for lower oleate concentrations (90 mM NaOl), the impact of mixing on long term growth becomes more apparent with an increase in sphericity and final particle size for round-bottom flask-based syntheses over thermocycler-based syntheses (Figure 1). Confirmation of Oleate Bilayer and Functionalization of AuNPs Envisioning the potential for biological applications, the compatibility of this newly established synthetic protocol with established post synthesis processing was tested and verified. Capping agent exchange was performed with fluorescein PEG thiol, MW 5k (FITC- PEG-SH, 5k) as a model for post-functionalization with a thiolated PEGs (Figure 11A). The strong fluorescence signal of FITC-PEG-SH, 5k allows to strictly verify a successful capping agent exchange (Figure 11B). It is known that gold nanoparticles efficiently quench the fluorescence of FITC attached to their surface even through PEG spacers (Schneider et al., 2006, Nano Letters, 6, 530; Dulkeith et al., 2005, Nano Letters, 5, 585). Free FITC-PEG-SH in the wash supernatant is detectable at concentration as low as 100 ppm. The absence of dye in the supernatant after repeated washing was verified via fluorometry, while at the same time Attorney Docket No.: 047162-5361-00WO confirming the presence of FITC-PEG-SH on the AuNP surface in the separated, particle-based fraction. FTIR confirms an oleate bilayer on the synthesized, quadruple-washed nanoparticles (Figure 11C). The presence of an asymmetric carboxylate band at 1560 cm-1, the absence of an asymmetric carboxylate band at around 1525 cm-1compared with the symmetric carboxylate band suggest a bidentate binding (Δνas(COO-), νs(COO-), 1560-1461=99 cm-1< 110 cm-1) (Cass et al., 2013, Analytical Chemistry, 85, 6974; Bronstein et al., 2007, Chemistry of Materials, 19, 3624). After capping agent exchange with FITC-PEG-SH, 5k and thorough washing, the decrease of the carboxylic band at 1556 cm-1is a strong indicator of the removal of oleate from the gold surface (Figure 11C). The band at 1069 cm-1indicates the presence of PEG. An additional wash does not change the FTIR fingerprint significantly, but it is noteworthy that an O-H band 3655 cm-1becomes visible. The broadening of the shoulder of the band region of 2950-2980 cm-1potentially indicates the presence of the N-H amine linking position of the PEG and FITC. Hydrodynamic diameter for the 27 / 1 and 9 / 1 ratio AuNPs are 20 nm and 70 nm, respectively, reflecting the hydrodynamic size increase of the oleate bilayer coating (Figure S3). Purified particles have a zeta potential of -20 mV and -35 mV in the 6-10 pH range for ratio 27 / 1 and 9 / 1, respectively (Figure 2A), and show improved stability in high PBS concentrations over citrate capped AuNPs (Figure 2A, Figure 2B). Oleate synthesized AuNPs can be autoclaved (Figure 12) and show moderate multi-day stability in complete cell growth solutions (DMEM complete, RPMI complete, and OptiMEM, Figure 13). Mechanism of Bilayer-Capped Gold Nanoparticle Growth To further elucidate the temperature and oleate concentration dependent growth kinetics, temperature controlled, stirred-cell time resolved UV-vis spectroscopy at 40 ºC and 70 ºC was performed testing two different NaOl / Au-precursor ratios of 27 / 1 and 9 / 1 (270 mM NaOl and 90 mM NaOl). At 40 ºC and 27 / 1 ratio, a continuous absorbance peak position increase in the region of 500-530 nm can be observed, coupled with a gradual peak shift from 506-510 nm, indicating a multi-hour, continuous particle growth (Figure 4A through Figure 4C). An increase in absorbance at localized surface plasmon resonance (LSPR) peak can be observed between 10 and 20 min with subsequent sharpening and redshift between 15 and 20 min suggesting cluster Attorney Docket No.: 047162-5361-00WO formation with subsequent nucleation (Figure 4A) (Chen et al., 2021, Journal of Physical Chemistry C, 125, 1087; Panariello et al., 2020, Journal of Physical Chemistry C, 124, 3624). A decrease in absorbance at the LSPR peak is observed from 20 to 35 min before a continuous absorbance increase (Figure 4C). These two observations suggest a nucleation process of gold nanoclusters, potentially inducing a pH shift in the of the reaction mix in the moment of nucleation, inducing oleate self-assembly (also see discussion on individual mechanism stages in the following). At 70 ºC and 27 / 1 ratio, the high gold nanoparticle particle density observed during the process limits reliable light transmission through the cuvette under the detection limit within less than 30 min from synthesis initiation (Figure 4D). Remarkably, the sodium oleate / oleic acid undergoes a self-assembly structural transformation over the course of the reaction (Figure 4E, Figure 4F). When pH values decrease below 9, sodium oleate assemblies transition from micelles to vesicles (Suga et al., 2016, Langmuir, 32, 7606; Lu et al., 2014, Journal of Physical Chemistry B, 118, 12511; Salentinig et al., 2010, Langmuir, 26, 11670), which can be measured by an onset of turbidity as absorbance at 800 nm during the synthesis. For ratios of 9 / 1 or lower, the observed onset of turbidity is temperature dependent, occurring after 45 min into the reaction at 40 °C (Figure 4E) and 5 min at 70 °C (Figure 4F). At the 27 / 1 ratio the comparatively long reaction time (several hours vs. < 1 h or less for the citrate method) and high pH (Figure 4G) resemble the previously reported citrate- based method at high pH, which closely follows a La Mer-type growth model, not postulating intra-particle ripening (Grus et al., 2020, ACS Nano, 14, 8689). Throughout the reaction, a pH drop occurs, followed by slight upward recovery of pH at both NaOl concentrations evaluated (Figure 4G, Figure 4H). Level in pH drop, but also time point of pH recovery are NaOl concentration dependent, explaining the observed difference in turbidity evolution between ratio 27 / 1 and 9 / 1 (Figure 4I). These observations are indicative for a multifunctional role of oleate in the synthesis as reductant, capping agent, as well as pH modulator (Park et al., 2014, Journal of the American Chemical Society, 136, 1907). Spectroscopic findings suggest four mechanistic stages during the oleate mediated synthesis of gold nanoparticles from tetrachloroauric acid as follows: Attorney Docket No.: 047162-5361-00WO Stage 1: Hydroxylation of the gold species ([(AuCl2(OH)2]- or [AuCl(OH)3]-) characteristic for gold nanoparticle syntheses from tetrachloroauric acid at high pH (Ji et al., 2007, Journal of the American Chemical Society, 129, 13939). Stage 2: Complexation begins via the deprotonated carboxylate-moiety of the oleic acid,[17, 26]followed by a continuous growth of gold nanoclusters through agglomeration of reverse micelles, and subsequent nucleation of crystalline Au (Chang et al., 2019, Journal of the American Chemical Society, 141, 7037). Stage 3: Formation of an energetically favorable oleate bilayer on gold nanoparticles (Cardellini et al., 2022, Journal of Physical Chemistry C, 126, 4483), or uptake of already formed gold nanoparticles with an oleate monolayer into bilayer-arrays of vesicles (Lee et al., 2013, Journal of the American Chemical Society, 135, 5950). The postulated pH and temperature-dependent self-assembly forms of the oleate and its different sizes in the aqueous medium might influence this process. Stage 4: Diffusion-controlled growth with enrichment of gold species in the electrical double layer (EDL) on existing nanoparticles, similar to the traditional citrate-based synthesis (Wuithschick et al., 2015, ACS Nano, 9, 7052). The limited transport rate of gold species through the oleate bilayer (several hours at 40-80 °C), results in slower steady growth as compared to citrate-based methods. The oleate-mediated syntheses were multiplexed in a plate reader with temperature control at 40 °C and integrated plate shaking to spectroscopically monitor the particle growth over the course of 24 h. The short light path lengths allow for the monitoring of the absorbance throughout the complete synthesis even after the formation of high concentrations of gold nanoparticles. Monitoring the absorbance at wavelengths 500 nm, 530 nm, and 800 nm reveals a time lag (15-30 min) with slight increase in absorbance followed by rapid increase in absorbance in the 500-530 nm region, indicating AuNP formation for syntheses with oleate concentrations of 270 mM-120 mM (27 / 1-12 / 1 ratio, Figure 3, Figure 5A). These syntheses have an initial pH (9.25 - 9.09) above the pH of vesicle formation in the oleate system. In support of the onset and progression of continuous growth after 45 - 60 mins observed for 270 mM in the temperature-controlled stirred-cell UV-Vis setup (Figure 4A), a continuous increase in absorbance at 530 nm for the ratios 27 / 1 (Figure 5A), 15 / 1, and 12 / 1 Attorney Docket No.: 047162-5361-00WO (Figure 3, Figure 5A) can be observed in the multiplexed synthesis monitoring setup. For ratio 9 / 1 (Figure 5B) and 6 / 1 (Figure 3A through Figure 3G), an increase followed by a drop in turbidity (as measured by absorbance at 800 nm) was observed, attributable to a dynamic evolution of reactant pH possibly due to gold precursor complexation with oleate (Figure 4G, Figure 4H) followed by a re-release of oleate as less overall oleate is involved in the capping and bilayer encapsulation of nucleated AuNPs. A close inspection of the absorbance at 800 nm for ratio 27 / 1 reveals an increase in turbidity peaking at 30 min supporting of the stirred-cell temperature-controlled shift at 800 nm and coinciding with the decrease in absorbance at the LSPR peak position from 20-35 min (Figure 4G, Figure 5B). These additional indicators further suggest dynamic pH shift as a result of the transition from gold oleate complexes to gold nanoparticles. Photoluminescent spectroscopy with the amphiphilic Laurdan, commonly used as a bilayer organization indicating fluorescent probe, was conducted to develop an additional indicator with a secondary reaction setup. Time-resolved, fluorescence experiments under temperature control and with stirring show a temperature dependent change in oleate self- assembly at 30 min for the 27 / 1 ratio at 40 °C vs.70 °C as measured by emission peak shift dynamics of Laurdan from 495 to 460 nm (Figure 14A). Further multiplexing of fluorescence in a 96-well plate (Figure 14B) supports the findings of a dynamic self-assembly process of oleate during the synthesis with time points following the pH measurements for ratio 27 / 1 and 9 / 1. Correcting the absorbance at 530 nm by turbidity (Abs.530nm-Abs.800nm) shows an increase in absorbance (Abs.0.5 to Abs.1.25 within less than 30 mins, Figure 5C) is likely only partially due to the formation of oleate vesicles, and mostly to faster nanoparticle growth compared to ratio 27 / 1 (Figure 5C, Figure 5D). Since the absorbance in the wavelength range for oleate at different pH-values and high concentrations (i.e., 90 mM) is nonlinear, multiple correction factors to the subtracted absorbance at a wavelength of 800 nm were assessed, all supporting the suggested findings (Figure 3H). Closely inspecting the time points of absorbance development for the 9 / 1 ratio finds that, the onset of a faster nanoparticle growth occurs before the occurrence of turbidity can be observed (30 min vs.60 min), indicating that a staged progression and particle nucleation preceded pH shift induced change in turbulence. Adjusting the pH of the reagent mixture for all oleate / Au precursor ratios to that of 270 mM (pH 9.25) by sodium hydroxide leads to a suppression of vesicle formation for oleate to precursor ratios of 9 / 1 Attorney Docket No.: 047162-5361-00WO (Figure 5B, 9 / 1 pH adj.) and 6 / 1 (Figure 3B, 6 / 1 pH adj.), but only partial suppression of vesicle formation for oleate to precursor ratios of 4.5 / 1 and 3 / 1 (Figure 3J) highlighting the changing pH during the gold nanoparticle growth. Comparing the increase in absorbance at 530 nm of the ratio 27 / 1, 9 / 1, and pH adjusted 9 / 1 further shows that pH dependent supply of hydroxylated gold precursor species is not the only contributor to the first growth stage but could play a significant role in growth stage 3-4. The higher oleate concertation (27 / 1) leads to a larger increase in absorbance (ΔAbs.530,0^40min ≈ 0.75 for 27 / 1 vs. ΔAbs.530,0^40min ≈ 0.25 for 9 / 1 and 9 / 1 pH ajd.) suggesting that the supply of oleate contributes to the nucleation of gold nanoparticles. In conjunction with the gradual, continuous growth observed from 1 h onwards, this behavior is in accordance with standard theories of larger numbers of nucleated particles (seeds) at the same amount of overall precursor supply yield smaller particles compared to a lower number of particles (Wuithschick et al., 2015, ACS Nano, 9, 7052), which is additionally supported by the increase in particle sizes obtained from synthesis aliquots at 3 hours and 24 hours, the particle sizes synthesized at different oleate / precursor ratios and the decrease in particle size for the same oleate ratio at upward adjusted pH (Figure 5E, Figure 5F). In summary, the critical role of the oleate precursor concentration is demonstrated by the early-stage growth rates of different oleate / precursor ratios (Figure 5C). The spectroscopic evaluation of different oleate / Au-precursor ratios at unadjusted and adjusted pH suggests, that the pH-dependent gold monomer supply is a limiting factor for NP-growth. Future investigations should focus on the determination of the role of the pH- and temperature-dependent self- assembly patterns of the oleate during stages 2 and 3 of the proposed growth process. This work demonstrates a one-step size-controlled synthesis of oleate capped gold nanoparticles in water, featuring high particle concentrations (2 mg Au / ml) at moderate reaction temperatures (40-80 ºC), only utilizing sodium oleate and tetrachloroauric acid. The method allows for seed-free synthesis of particle sizes in the range of 8-14 nm, with size variations (CV) of 12-17%, as well as the seed-free synthesis of particle sizes up to 39 nm at the cost of increased size variation and anisotropy. Ligand exchange protocols on the gold nanoparticles are straightforward and compatible with common gold nanoparticle functionalization protocols. The potential Attorney Docket No.: 047162-5361-00WO applicability of the developed synthetic protocol is showcased by ease of scale-up (to gram- level), and its versatility further emphasized by the possibility to conduct gold nanoparticle synthesis and optimization in thermocyclers and plate readers. Detailed testing of the synthesis parameter space and close spectroscopic monitoring of the synthesis indicates the oleate- mediated gold nanoparticle growth occurring in stages, resembling previously reported citrate- based gold nanoparticle growth processes at neutral and basic conditions. From a practical perspective, this work provides a promising approach to an automated and much-simplified gold nanoparticle synthesis with standardized reactors and accordingly adapted process development. In summary, the present work provides a new, high concentration aqueous gold nanoparticle synthesis utilizing oleate as reducing, capping and bilayer encapsulation agent. The strategies presented for multiplexing the oleate synthesis and the ready scale-up should significantly facilitate the production-scale synthesis of gold nanoparticles with controlled particle sizes. As described, multiplexed synthesis approaches could lead to the faster formulation development for fatty acid mediated nanoparticle growth models, among others. By utilizing thermocyclers as low cost reactor systems, the fatty acid synthesis is highly temperature controlled within a temperature regime of 40 ºC – 100 ºC at a precision with temperature ramps for heat up and cool down, as well as holding temperature of ± 0.1 ºC in an unattended reaction setup over multiple hours or days. The use of standardized reaction systems is also demonstrated with precision temperature control over long timeframes and standardized reaction vessels, such as thermocyclers (reaction system) and standardized 96-well plates (reaction vessel) or standardized PCR tubes (reaction vessel). This yields an easy synthesis process with equipment that is present in life-science oriented laboratories. The single use of low cost 96-well plates or PCR tubes eliminates the danger of cross-contamination and the need for extensive cleaning for nanoparticle growth procedures when using standard laboratory glassware and improves lab-to-lab reproducibility. Specifically, for gold nanoparticles, it has been demonstrated that: the syntheses can proceed at 50-times higher concentrations (larger space yield) compared to the standard inverted Turkevich synthesis; the reaction can be monitored via UVvis spectral analysis in a spectrophotometer plate reader that has the capability of reading defined spectra of each plate well during time intervals; and through tailoring the ratio of fatty acid to gold precursor Attorney Docket No.: 047162-5361-00WO (tetrachloroauric gold) in the aqueous reaction mixture, as well as through changing the reaction pH, different gold nanoparticle sizes in the range of can be obtained reproducibly in the range of at least 8-35 nanometers) in a single step synthesis without the need of nanoseeds. For iron oxide nanoparticles, it has been demonstrated that: very small, sub 5nm nanoparticles can be synthesized; the synthesis can proceed in a single step in a thermocycler give longer synthesis times (72 hours) than conventional fatty acid mediated syntheses. In exchange, the synthesis can be unattended and proceeds at lower (<100 ºC) temperatures. As a single step synthesis, the approach does not need the first step of synthesizing iron oleate and then decomposing the iron oleate in an organic solvent system at high temperatures (>300 ºC). Lastly, the synthesis is performed in an aqueous environment. All reagents utilized herein can be prepared and premixed at room temperature without progression of nanoparticle growth. The premixing minimizes the influence of reagent addition time points leading to a simpler reaction handling. The possibility to premix all reagents before heating the reagent mixture up in a thermocycler or plate reader enables workflow integration with robotic liquid handler workstations. For gold nanoparticles, it has been demonstrated that the high concentrations at which the reaction proceeds still yields practically amounts of gold nanoparticles. Three PCR tubes filled at 0.2 µl at standard reaction concentration yield approximately the as many nanoparticles as a 25 ml standard inverted Turkevich synthesis. One 96 well-plate yields approximately as much as a scaled up 1-liter inverted Turkevich synthesis. The fatty acid templated synthesis yields sterically capped nanoparticles. Ultimately, the invention minimizes the need skilled labor, which is a large cost contributor in the manufacturing of nanoparticles, due to: current conventional glassware batch- to-batch wet chemistry: a slightly different position of the heating band, a slightly different heating ramp, slightly different time points, or a different stir bar size and speed can lead to different results in metal nanoparticle synthesis); and the low experimental throughput of different parameter combinations to manually synthesize at the same time by observing multiple round bottom flasks in a fume hood and adhering to all reagent addition time points in a synthesis. Fatty acid capped nanoparticles are stable at environmental conditions over multiple months. The increased stability and the decreased cost of production might make metal Attorney Docket No.: 047162-5361-00WO nanoparticles that were previously only affordable for high value applications (such as life sciences) more suitable to larger volume, lower value applications (catalysis, environmental remediation). Example 2: Process Summary In summary, the metals evaluated (precursor in parentheses) were gold (HAuCl4), iron (FeCl3), zinc (zinc acetate), copper (CuCl2and CuSO4), and manganese (MnCl2), wherein the metal precursor concentrations (conc.) were 0.4-10 mM, the fatty acid salt concentrations were 45 - 270 mM, fatty acid salt type were sodium oleate, sodium palmitate, and potassium oleate, temperatures ranged from 10 °C - 80 °C, and synthesis duration ranged from 10 min - 72 h. The standard setting was 24 h, but particles nucleate within a few minutes at 70 °C, and continue to grow Nanoparticle sizes achieved (only evaluated for gold nanoparticles) ranged from 8 - 40 nm in diameter, spherical, as well as gold nanoseeds (sub 3 nm). Capping composition (only evaluated for gold nanoparticles) were fatty acid bilayer directly out of synthesis, ligand exchange demonstrated with thiolated PEGs and lipoic acid. Gold nanoseeds were sized using TEM (Figure 15) and characterization of platinum and platinum-gold nanoparticles was performed using TEM and energy dispersive x-ray (EDX) (Figure 16 and Figure 17). The following is a table of the range of conditions which yielded metal nanoparticles. Fatty Conc. in Metal Conc. in Synthesis Synthesis Product Product Reactor Acid final Salt final temp. time evaluation system Salt reaction reaction used mix mix 1 Sodium 270 mM HAuCl410 mM 70°C 24 h AuNP, dmean= 8.6 Round Oleate fatty nm bottom acid CV = flask, at bilayer 19.1% 250 ml, coated 0.5 g Au scale 2 Sodium 270 mM HAuCl410 mM 70°C 24 h same dmean= 8.5 Thermocy Oleate nm cler CV = 11.9% 3 Sodium 150 mM HAuCl410 mM 70°C 24 h same dmean= Thermocy Oleate 10.3 nm cler CV = 13.0% Attorney Docket No.: 047162-5361-00WO Sodium 120 mM HAuCl410 mM 70°C 24 h same dmean= Thermocy Oleate 14.2 nm cler CV = 16.8% Sodium 90 mM HAuCl410 mM 70°C 24 h same dmean= Round Oleate 19.2 nm bottom CV = flask 30.1% (0.05g intermedi ate scale- up) and thermocy cler Sodium 60 mM HAuCl410 mM 70°C 24 h same dmean= Thermocy Oleate 19.6 nm cler CV = 36.1% Sodium 45 mM HAuCl410 mM 70°C 24 h same dmean= Thermocy Oleate 39.1 nm cler CV = 38.9% Sodium 30 mM HAuCl410 mM 70°C 24 h Macros Thermocy Oleate copic cler particles Sodium 48 mM HAuCl40.4 mM 70°C 24 h Gold 20nm by In-situ Oleate nanopar liquid liquid ticles, TEM TEM and fatty thermocy acid cler bilayer coated Sodium 270 mM HAuCl410 mM 70°C 3 h same UV- Thermocy Oleate Vis:LSPR cler peak at 520, no TEM evaluation Sodium 270 mM HAuCl410 mM 70°C 0 h - 24 h same Time- Thermocy Oleate resolved cler UV-vis and plate- reader UV-Vis. Nucleation onset after a few minutes Sodium 90 mM HAuCl410 mM 70°C 3 h same Gold Thermocy Oleate nanopartic cler les: LSPR peak at 520, no TEM evaluation Attorney Docket No.: 047162-5361-00WO Sodium 120 mM HAuCl410 mM 70°C 3 h same Gold Thermocy Pal- nanopartic cler mitate les: LSPR peak at 520, no TEM evaluation Po- 270 mM HAuCl410 mM 70°C 3 h same Gold Thermocy tassium nanopartic cler Oleate les: LSPR peak at 520, no TEM evaluation Sodium 270 mM HAuCl410 mM 40°C 24 h same dmean= 6.9 Thermocy Oleate nm cler CV = 16.9% Sodium 270 mM HAuCl410 mM 60°C 24 h same dmean= 8.3 Thermocy Oleate CV = cler 21.7% Sodium 270 mM HAuCl410 mM 80°C 24 h same dmean= 9.9 Thermocy Oleate CV = cler 14.0% Sodium 270 mM HAuCl410 mM 10°C 24 h same UV-Vis Round Oleate bottom flask Sodium 270 mM FeCl310 mM 70°C 72 h Iron UV-Vis Thermocy Oleate oxide analysis + cler nanopar TEM. ticles, TEM likely shows sub goethite 5 nm particles Sodium 270 mM Zinc 10 mM 70°C 72 h Zinc UV-Vis Thermocy Oleate Acetate oxide cler nanopar ticles Sodium 270 mM CuCl210 mM 70°C 72 h Copper UV-Vis Thermocy Oleate oxide cler nanopar ticles Sodium 270 mM CuSO410 mM 70°C 72 h Copper UV-Vis Thermocy Oleate oxide cler nanopar ticles Sodium 270 mM MnCl210 mM 70°C 72 h Manga- UV-Vis Thermocy Oleate nese cler oxide nanopar ticles Sodium Sodium HAuCl40.5 mM 25°C 3 h Gold UV-Vis + Round Oleate oleate = nanosee TEM bottom and As- 50mM ds (sub dmean= 2.9 flask 3nm) nm Attorney Docket No.: 047162-5361-00WO corbic Ascorbi CV = acid c acid = 25.4% 1.5mM 25 Sodium 270 mM H2PtCl610 mM 70°C 24 h Plati- UV-Vis + Thermocy Oleate num TEM cler nano- particles 26 Sodium 90 mM H2PtCl610 mM 70°C 24 h Plati- UV-Vis Thermocy Oleate num cler nano- particles 27 Sodium 270 mM Na2PtCl 10 mM 70°C 24 h Plati- UV-Vis + Thermocy Oleate4num TEM cler nano- particles 28 Sodium 90 mM Na2PtCl 10 mM 70°C 24 h Plati- UV-Vis Thermocy Oleate4num cler nano- particles 29 Sodium 270 mM H2PtCl65 mM 70°C 24 h Plati- UV-Vis + Thermocy Oleate + (H2PtCl6) num TEM cler HAuCl4+ 5 mM nano- (including (HAuCl4particles HAADF- ) STEM- EDX mapping) 30 Sodium 90 mM H2PtCl65 mM 70°C 24 h Plati- UV-Vis Thermocy Oleate + (H2PtCl6) num cler HAuCl4+ 5 mM nano- (HAuCl4particles ) 31 Sodium 270 mM Na2PtCl 5 mM 70°C 24 h Mixed- UV-Vis Thermocy Oleate4+ (Na2PtCl metal cler HAuCl4 4+ 5 mM plati- (HAuCl4num – ) gold nano- particles 32 Sodium 90 mM Na2PtCl 5 mM 70°C 24 h Mixed- UV-Vis Thermocy Oleate4+ (Na2PtCl metal cler HAuCl4 4+ 5 mM plati- (HAuCl4num – ) gold nano- particles 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 variations of this invention may be devised by others skilled in the art without departing from the Attorney Docket No.: 047162-5361-00WO 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.: 047162-5361-00WO CLAIMS What is claimed is:

1. A method of synthesizing a nanoparticle, comprising the steps of: providing a metal solution comprising at least one metal precursor and at least one solvent; providing a fatty acid solution comprising at least one fatty acid and at least one solvent; combining the metal solution and the fatty acid solution to provide a combined solution; and collecting the nanoparticle from the combined solution.

2. The method of claim 1, wherein the at least one metal precursor comprises an element selected from the group consisting of palladium, manganese, silver, gold, zinc, copper, iron, cobalt, nickel, platinum, any oxidation state thereof, and any combination thereof.

3. The method of claim 1, wherein the at least one metal precursor comprises gold.

4. The method of claim 1, wherein the at least one metal precursor is selected from the group consisting of chloroauric acid, iron chloride, copper chloride, manganese chloride, chloroplatinic acid, sodium tetrachloroplatinate, and combinations thereof.

5. The method of claim 1, wherein the metal solution has a metal precursor concentration of between 0.1 mM and 50 mM.

6. The method of claim 1, wherein the at least one fatty acid is selected from the group consisting of oleic acid, palmitoleic acid, linoleic acid, palmitic acid, lauric acid, vaccenic acid paullinic acid, elaidic acid, gondoic acid, erucic acid, nervonic acid, mead acid, myristic acid, salts thereof, and esters thereof.Attorney Docket No.: 047162-5361-00WO 7. The method of claim 1, wherein the fatty acid solution has a fatty acid concentration of between 30 mM and 300 mM.

8. The method of claim 1, wherein the ratio of the at least one fatty acid to the at least one metal precursor is between 3:1 and 30:

1.

9. The method of claim 1, wherein the fatty acid solution further comprises a salt of the at least one fatty acid.

10. The method of claim 1, wherein the concentration of the nanoparticle in the combined solution is between 1 mM and 20 mM.

11. The method of claim 1, wherein the step of providing a fatty acid solution further comprises the step of heating the fatty acid solution.

12. The method of claim 1, wherein the step of combining the metal solution and the fatty acid solution further comprises the step of heating the combined solution.

13. The method of claim 12, wherein the combined solution is heated to a final temperature between 30 °C to 100 °C.

14. The method of claim 1, wherein the step of collecting the nanoparticle from the combined solution comprises the step of centrifuging the combined solution.

15. The method of claim 1, further comprising the step of combining the nanoparticle with a capping agent.

16. The method of claim 15, wherein the capping agent comprises at least one functionality selected from the group consisting of a thiol, polyethylene glycol (PEG), and a fluorescein dye.Attorney Docket No.: 047162-5361-00WO 17. A nanoparticle synthesized using the method of claim 1.

18. The nanoparticle of claim 17, wherein the nanoparticle has a diameter of about 5 nm to about 40 nm.

19. A composition comprising the nanoparticle of claim 17 and a solvent.

20. The composition of claim 19, wherein the solvent is selected from the group consisting of Dulbecco’s Modified Eagle Medium (DMEM), Rosswell Park Memorial Institute Medium (RPMI), and Minimum Essential Medium (MEM).

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