Abstract: The present invention provides methods and compositions for amplifying the detection signal in surface plasmon resonance (SPR)-based flow systems. The signal amplification methods comprise the use of well established marker systems that provide a precipitate. The marker systems include, for example, enzyme and nucleation systems. Enzymes suitable for use as a marker system include peroxidases and phosphatases. The amplification system is useful in any SPR-based detection system including microfluidic systems, e.g., “lab on a chip” systems and the like. The methods can comprise any SPR-based assay format, including typical immunoassay formats. The immunoassay formats can include competitive and sandwich assays. Analyte capture agents can include antibodies, lectins, carbohydrates, polynucleotides, receptor proteins, and the like.

Abstract: The invention provides a method, apparatus and system for detecting electrochemical oxidoreduction activity mediated by a redox enzyme at a site remote from the enzyme. In one embodiment, the method comprises immobilizing the redox enzyme on a first region of a conductive surface and contacting a substrate capable of producing a detectable signal upon oxidation or reduction with a second region of the conductive surface. The second region is electrically coupled with the first region and the redox enzyme is not present in the second region. The method further comprises exposing the immobilized redox enzyme to conditions that effect oxidation or reduction of the enzyme, and detecting oxidation or reduction of the substrate at the second region. The invention can be adapted for detecting a plurality of analytes.