Silver nanoplate compositions and methods
Embodiments of the present invention relate to methods for preparing high optical density solutions of nanoparticle, such as nanoplates, silver nanoplates or silver platelet nanoparticles, and to the solutions and substrates prepared by the methods. The process can include the addition of stabilizing agents (e.g., chemical or biological agents bound or otherwise linked to the nanoparticle surface) that stabilize the nanoparticle before, during, and/or after concentration, thereby allowing for the production of a stable, high optical density solution of silver nanoplates. The process can also include increasing the concentration of silver nanoplates within the solution, and thus increasing the solution optical density.
1. A silver nanoplate solution made by a process comprising the steps of:
forming a plurality of silver seeds from a solution, wherein the solution comprises a reducing agent, a first stabilizing agent selected from a salt, a polymer, or a biomolecule, and a silver salt;
growing the plurality of silver seeds into a plurality of silver nanoplates in the solution;
adding a buffer to the solution comprising the plurality of silver nanoplates;
adding a second stabilizing agent to the solution comprising the plurality of silver nanoplates, wherein the second stabilizing agent comprises at least one of the group consisting of: an aminopropyltriethoxysilane (APTES), a lipoic acid, a mercaptohexadecanoic acid, a mercaptoundecanoic acid, and a dihydrolipoic acid; and
concentrating the solution of silver nanoplates until a peak optical density of the solution is greater than about 10 cm −1 , wherein the silver nanoplate solution comprises concentrated silver nanoplates that preserve shape post-concentration while increasing optical density.
2. The silver nanoplate solution of claim 1 , wherein the first stabilizing agent comprises a polymer, polyvinyl pyrollidone, polyvinyl alcohol, polyethylene glycol, dextran, a monosaccharide, a disaccharide, an oligosaccharide, a polysaccharide, a lipoic acid, or a thiol-containing molecule.
3. The silver nanoplate solution of claim 1 , wherein the silver nanoplates have at least one of: (a) an aspect ratio of between 1.5 and 50, (2) an edge length between 10 nm and 300 nm, or (3) an absorption spectrum of the silver nanoplates comprises a peak wavelength of between 500 and 1500 nm.
4. The silver nanoplate solution of claim 1 , wherein the buffer is a sulfate, carbonate, chromate, borate, phosphate, sulfite, acetate, or nitrate.
5. The silver nanoplate solution of claim 1 , wherein the silver nanoplates are functionalized with a functional group or groups selected from one or more of the following: an amine, thiol, acrylate, alkyne, maleimide, silane, azide, hydroxyl, lipid, disulfide, fluorescent molecule, biotin, or combinations thereof.
6. The silver nanoplate solution of claim 5 , wherein the process further comprises the steps of:
isolating the concentrated silver nanoplates; and
encapsulating the isolated concentrated nanoplates with silica.
7. The silver nanoplate solution of claim 6 , further comprising the step of concentrating the encapsulated silver nanoplates to an optical density greater than 100 cm −1 .
8. The silver nanoplate solution of claim 1 , wherein the process further comprises contacting the silver nanoplate solution with a metal oxide in an amount sufficient to form a metal oxide coating on an exterior surface of the silver nanoplates.
9. The silver nanoplate solution of claim 1 , wherein the silver nanoplates are coated with a shell having a thickness of between 2 and 100 nm.
10. The silver nanoplate solution of claim 1 , wherein the polymer is selected from polystyrene sodium sulfonate, polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), polysaccharides, phenol, tannic acid, dextran, polyethylene glycol (PEG), or PEG molecules that contain one or more chemical groups selected from amine, thiol, acrylate, alkyne, maleimide, silane, azide, hydroxyl, lipid, disulfide, fluorescent molecule, or biomolecule moieties.
11. The silver nanoplate solution of claim 1 , wherein the silver nanoplates are functionalized with proteins, peptides, oligonucleotides, biotin, alkane thiols, lipoic and dihydrolipoic acid and derivatives of these acids, bovine serum albumin, streptavidin, neutravidin, wheat germ agglutinin, naturally occurring and synthetic oligonucleotides and peptides, or synthetic oligonucleotides with one or more chemical functional groups selected from amine, thiol, dithiol, acrylic phosphoramidite, azide, digoxigenin, alkynes, or biomolecules.