Protected nano-particle assemblies

Abstract

A spectroscopically active nano-particle assembly is provided. The nano-particle assembly includes a cluster of metallic nano-particles. A first protective coating is formed over a first side of the cluster, and a second protective coating is formed over a second side of the cluster, wherein the second side of the cluster is opposite the first side.

What is claimed is: 
     
         1 . A spectroscopically active nano-particle assembly, comprising:
 a cluster comprising metallic nano-particles;   a first protective coating formed over a first side of the cluster; and   a second protective coating formed over a second side of the cluster, wherein the second side of the cluster is opposite the first side.   
     
     
         2 . The spectroscopically active nano-particle assembly of  claim 1 , wherein the cluster of metallic nano-particles comprise gold, silver, or both. 
     
     
         3 . The spectroscopically active nano-particle assembly of  claim 1 , wherein the cluster of metallic nano-particles comprise aluminum, copper, or a noble metal, or any combinations thereof. 
     
     
         4 . The spectroscopically active nano-particle assembly of  claim 1 , wherein the cluster comprises five metallic nano-particles. 
     
     
         5 . The spectroscopically active nano-particle assembly of  claim 1 , wherein the cluster of metallic nano-particles comprises reporter molecules. 
     
     
         6 . The spectroscopically active nano-particle assembly of  claim 1 , wherein the first protective coating, the second protective coating, or both, comprises silicon dioxide, metal oxides, metal nitrides, or metal carbides, or any combinations thereof. 
     
     
         7 . A method for using a spectroscopically active nano-particle assembly, comprising:
 forming a first protective coating over a plurality of collapsed groups to form protected collapsed groups, wherein each collapsed group comprises a cluster of metal caps in proximity to each other, and wherein each metal cap is at a top of a flexible stalk;   pressing the plurality of protected collapsed groups into a film layer that has been softened by heating;   removing each of the flexible stalks, leaving metal clusters embedded in the film layer;   cooling the film layer to harden the film layer;   forming a second protective coating over the film layer and the metal clusters embedded in the film layer; and   dissolving the film layer to free the metal clusters.   
     
     
         8 . The method of  claim 7 , comprising functionalizing the first protective coating, the second protective coating, or both. 
     
     
         9 . The method of  claim 7 , comprising:
 injecting the spectroscopically active nano-particle assembly into a living organism; and   performing a spectroscopic analysis on the spectroscopically active nano-particle assembly in the living organism.   
     
     
         10 . The method of  claim 7 , comprising:
 forming a plurality of flexible columnar structures on a substrate;   forming a metal coating over the plurality of flexible columnar structures, wherein the metal coating forms a cap over a top surface of each of the plurality of flexible columnar structures;   placing a fluid over the plurality of flexible columnar structures; and   evaporating the fluid, wherein evaporation of the fluid exerts a microcapillary pressure that pulls the plurality of flexible columnar structures together into the plurality of collapsed groups, wherein each collapsed group comprises at least two flexible columnar structures.   
     
     
         11 . The method of  claim 10 , comprising dissolving a reporter molecule into the fluid, wherein the reporter molecule is trapped between two adjoining metal caps during the evaporation. 
     
     
         12 . The method of  claim 10 , comprising forming collapsed groups comprising a pentamer of metal caps. 
     
     
         13 . An analysis solution, comprising a suspension of spectroscopically active nano-particle assemblies, wherein each of spectroscopically active nano-particle assembly comprises:
 a cluster comprising metallic nano-particles;   a first protective coating formed over a first side of the cluster; and   a second protective coating formed over a second side of the cluster, wherein the second side of the cluster is opposite the first side.   
     
     
         14 . The analysis solution of  claim 13 , wherein the spectroscopically active nano-particle assemblies are configured to be used in a surface enhanced Raman spectroscopy analysis. 
     
     
         15 . The analysis solution of  claim 13 , wherein the first protective coating, the second protective coating, or both, comprise a functional group to promote stability in the analysis solution, bind to a specific substrate, or both.