Patent ID: 7432112

Claim:
A method for detecting a biomolecule in a sample, comprising a) preparing a metallic colloid by contacting metal cations with a reducing agent in aqueous solution and subsequently heating the aqueous solution, the metallic colloid containing metallic particles; b) modifying a metallic surface of the particles with a Raman-enhancing organic molecule having affinities for the metallic surface and for the biomolecule to produce surface-modified metallic particles, wherein the Raman-enhancing organic molecule comprises a bi-functional organic molecule having a first moiety that has an affinity for the metallic surface and a second moiety that has an affinity for the biomolecule, and the first and second moieties are different, c) aggregating a plurality of the surface modified metallic particles to form a cluster of surface-modified metallic particles, d) contacting the surface-modified metallic particles with the biomolecule, and e) detecting SERS signals emitted by the biomolecule, wherein the signals are indicative of the presence of the biomolecule.