Patent ID: 7351591

Claim:
A method for producing a cluster of surface-modified metallic colloid comprising (1) metallic colloid comprising a metal and (2) a Raman-enhancing organic molecule on a surface of the metallic colloid, the method comprising: preparing a solution comprising cations of the metal and a reducing agent by dissolving the cations and the reducing agent in the solution, subsequently heating the solution to produce the metallic colloid, modifying the metallic colloid by attaching the Raman enhancing organic molecule to the surface of the metallic colloid to produce the surface modified metallic colloid, wherein the Raman-enhancing organic molecule comprises a moiety that has an affinity for the metallic colloid and another moiety that has an affinity for a biomolecule, and aggregating a plurality of the surface-modified metallic colloid to form the cluster of surface-modified metallic colloid.