Biosensors including metallic nanocavities

Abstract

A biomolecular assay includes a substrate with a metallic layer on at least one surface thereof. The metallic film includes nanocavities. The nanocavities are configured to enhance signals that are representative of the presence or amount of one or more analytes in a sample or sample solution, and may be configured to enhance the signal by a factor of about two or more or by a factor of about three or more. Such signal enhancement may be achieved with nanocavities that are organized in an array, randomly positioned nanocavities, or nanocavities that are surrounded by increased surface area features, such as corrugation or patterning, or nanocavities that have quadrilateral or triangular shapes with tailored edge lengths, or with a plurality of nanoparticles. Methods for fabricating biomolecular substrates and assay techniques in which such bimolecular substrates are used are also disclosed.

What is claimed is: 
     
         1 . An apparatus for use in a biomolecular assay, comprising:
 a substrate; and   a metallic layer on at least one surface of the substrate, the metallic layer including a plurality of nanocavities, wherein the nanocavities create an exposed surface of the substrate.   
     
     
         2 . The apparatus of  claim 1 , wherein the substrate is substantially planar. 
     
     
         3 . The apparatus of  claim 1 , wherein the metallic layer comprises gold. 
     
     
         4 . The apparatus of  claim 1 , wherein the at least one nanocavity is configured to enhance a signal representative of an amount of at least one analyte present in a sample. 
     
     
         5 . The apparatus of  claim 1 , further comprising capture molecules immobilized within the plurality of nanocavities. 
     
     
         6 . The apparatus of  claim 5 , wherein at least some of the capture molecules are immobilized to surfaces of the metallic layer within the plurality of nanocavities. 
     
     
         7 . The apparatus of  claim 1 , wherein at least a portion of the plurality of nanocavities are configured to enhance a signal representative of an amount of at least one analyte present in a sample. 
     
     
         8 . The apparatus of  claim 7 , wherein the metallic layer is configured to enhance a fluorescence signal that indicates binding of at least one of an analyte and a competing molecule with a capture molecule within a nanocavity of the metallic substrate. 
     
     
         9 . The apparatus of  claim 1 , wherein the substrate comprises quartz. 
     
     
         10 . A biomolecular assay technique, comprising:
 introducing a sample or sample solution into nanocavities of the apparatus of  claim 5 ;   introducing electromagnetic radiation into the substrate, wherein at least some of the electromagnetic radiation is internally reflected within the substrate;   detecting at least one enhanced signal from the nanocavities representative of a presence or amount of at least one type of analyte present in the sample.