Patent ID: 8043868

Claim:
A method for determining the concentration of an analyte within a sample, the method comprising: providing a first substrate comprising a conductive region and a recognition layer, the conductive region having a first surface operatively coupled with the recognition layer, the recognition layer comprising at least one recognition molecule, wherein said conductive region comprises at least one particle formed of a conductive material and having a hollow tubular shape with an average diameter of less than 300 nm and wherein the distance between the first surface of the conductive region and the recognition molecule is selected such that when the analyte is bound to the recognition layer the combination of the at least one particle and the analyte exhibits a particle plasmon effect when radiation is directed through the conductive region and the recognition layer; contacting the substrate with the sample to bind at least some of any analyte present in the sample with the recognition molecule; directing radiation through the conductive region and the recognition layer, measuring at least a part of a spectrum of radiation that is absorbed or transmitted by or through the substrate and manifesting a particle plasmon effect; comparing the at least part of the spectrum with a reference spectrum and determining the difference; and determining the concentration of the analyte from the difference.