Surface plasmon resonance detection and multispot sensing for direct monitoring of interactions involving low-molecular-weight analytes and for determination of low affinities.

Surface plasmon resonance detection allows direct observation of molecular interactions between an analyte in solution and its immobilized binding partner. The use of simultaneous monitoring of interaction events on multiple sensing surfaces, with varying amounts of immobilized receptor, for detection of low-molecular-weight analytes and for determination of low affinities was investigated. Using multispot sensing and BIAcore 2000 instrumentation, analytes as small as 180 Da were detected and affinities in the 50 microM range could be determined. The use of multispot sensing thus extends direct interaction analysis to include low-molecular-weight analytes and low-affinity interactions.