Composite Nanoparticle Structures for Chemical and Biological Sensing

Abstract

Described herein is a nanoparticle that enhances the interaction of the nanoparticle and/or a molecule/material deposited on the surface of the nanoparticle with light, comprising a pair of stacked metallic disks separated by a non-metallic spacer, wherein: (a) the dimensions of the disks and spacer are smaller than the wavelength of the light; and (b) the nanoparticle enhance the light interaction at least three times greater than that an individual metallic disk. Methods for making the nanoparticle and methods for using the nanoparticle in a variety of assays are also provided.

What is claimed is: 
     
         1 . A nanoparticle that enhances the interaction of the nanoparticle and/or a molecule/material deposited on the surface of the nanoparticle with light, comprising a pair of stacked metallic disks separated by a non-metallic spacer, wherein:
 (a) the dimensions of the disks and spacer are smaller than the wavelength of the light; and   (b) the nanoparticle enhance the light interaction at least three times greater than that an individual metallic disk.   
     
     
         2 . The nanoparticle of any prior claim, wherein the light interaction includes light absorption, light scattering, light reflection, and light radiation. 
     
     
         3 . The nanoparticle of any prior claim, wherein the light interaction includes Raman scattering, color production, and luminescence that includes fluorescence, electroluminescence, chemiluminescence, and electrochemiluminescence. 
     
     
         4 . The nanoparticle of any prior claim, wherein the light interaction comprises interactions of light with a materials or molecule that is deposited on the nanoparticle. 
     
     
         5 . The nanoparticle of  claim 4 , wherein the molecules are analytes that have been captured on the surface of the nanoparticle. 
     
     
         6 . The nanoparticle of  claim 4  or  5 , wherein the analytes are selected from proteins, peptides, DNA, RNA, nucleic acid, small molecules, cells, and nanoparticles with different shape. 
     
     
         7 . The nanoparticle of any prior claim, wherein the nanoparticle further comprises two masking layers covering the exterior surfaces of the metallic disks but a portion of the edges of the disks. 
     
     
         8 . The nanoparticle of any prior claim, wherein the nanoparticle further comprises a magnetic or magnezable disk that can be attracted to a magnet. 
     
     
         9 . The nanoparticle of  claim 8 , wherein the magnetic or magnezable disk has a thickness in the range of 5 to 50 nm. 
     
     
         10 . The nanoparticle of any prior claim, wherein the nanoparticle further comprises at least one metallic nano-dot on the edge of the spacer and/or the metallic disk. 
     
     
         11 . The nanoparticle of  claim 10 , wherein the nano-dots have a diameter in the range of 5 nm to 15 nm. 
     
     
         12 . The nanoparticle of any prior claim, wherein the disks have the shape selected from round, polygonal, pyramidal, elliptical, elongated bar shaped, or any combination thereof. 
     
     
         13 . The nanoparticle of any prior claim, wherein the metallic and the spacer have the same and similar lateral dimension. 
     
     
         14 . The nanoparticle of any prior claim, wherein, for light enhancement in 800 nm wavelength and near by region, the disks have a significantly round shape of diameter from 30 nm to 100 nm, the top metallic disk thickness is from 5 nm to 30 nm, the spacer thickness is from 2 to 30 nm, and the bottom metallic disk thickness is from 5 nm to 30 nm. 
     
     
         15 . The nanoparticle of any prior claim, wherein the nanoparticle further comprises a magnetic or magnezible disk, that can be attracted to a magnet. 
     
     
         16 . The nanoparticle of any prior claim, wherein the stacked metallic disks are made of the same or different materials. 
     
     
         17 . The nanoparticle of any prior claim, wherein the material for the metallic disks is selected from the group consisting of gold, silver, copper, aluminum, alloys thereof, and combinations thereof. 
     
     
         18 . The nanodevice of any prior claim, wherein the distance between the pair of the metallic disk is in the range of 0.1 nm to 20 nm, for the light wavelength of 800 nm and around. 
     
     
         19 . The nanodevice of any prior claim, wherein the lateral dimension of said metallic disc is in the range from 5 nm to 150 nm. 
     
     
         20 . The nanodevice of any prior claim, wherein said metallic disc and the metallic back plane are spaced by a distance in the range of 0.1 nm to 60 nm. 
     
     
         21 . The nanodevice of any prior claim, wherein said at least one metallic dot structure has dimensions in the range of 1 nm to 25 nm. 
     
     
         22 . The nanodevice of any prior claim, wherein the distance between said metallic dot structure and said metallic disc, and the distance between said metallic dot structure and said metallic backplane is in the range of 0.5 nm to 50 nm. 
     
     
         23 . A method of making a free-standing nanoparticle, comprising:
 (a) obtaining a template comprising a plurality of pillars on the surface, wherein the height of the pillar is greater than the thickness of the material to be deposited;   (b) depositing one of more materials on the top surface with the pillars using a beam of the materials, in the direction substantially normal to the surface of the template;   (c) separating the deposited materials on top of the pillars from the pillars, thereby producing said nanoparticles.   
     
     
         24 . The method of  claim 23 , wherein the pillars have a top area of the shape selected from round, polygonal, pyramidal, elliptical, elongated bar shaped, or any combination thereof. 
     
     
         25 . The method of  claim 23  or  24 , wherein the method comprises a step of depositing a magnetic or magnetizable layer on the stack produced in step b). 
     
     
         26 . An assay for analyte detection, comprising:
 (a) bringing an analyte into proximity to or in contact with a free-standing nanoparticle comprising a pair of stacked metallic disks separated by a non-metallic spacer;   (b) illuminating free-standing nanoparticle with light that has a wavelength that is larger than the dimensions of the disks and spacer;   (c) detecting an outgoing signal from said analyte and/or free-standing nanoparticle.   
     
     
         27 . The assay of  claim 26 , wherein the signal is selected from the group consisting of light absorption, light scattering, light reflection, and light radiation. 
     
     
         28 . The assay of  claim 26  or  27 , wherein the detecting is done by detecting Raman scattering, color production, and/or luminescence that includes fluorescence, electroluminescence, chemiluminescence, and electrochemiluminescence. 
     
     
         29 . The assay of any of  claims 26 - 28 , wherein the analyte is bound by a capture agent that is on the surface of the nanoparticle. 
     
     
         30 . The assay of any of  claims 26 - 29 , wherein the analyte is selected from protein, peptides, DNA, RNA, nucleic acid, a small molecule, cell, and nanoparticle with different shape.