Studies on amplified assay of surface plasmon resonance immunosensing

Surface plasmon resonance (SPR) immunosensor is a relatively new immunoassay technique and has been receiving more and more attention in recent years. However, a major disadvantage of SPR for bio-analytical applications is that low concentration or low molecular mass analytes could not be detected directly. Therefore, it is a challenging task to develop strategies for improving the detection limit/sensitivity of SPR. In this paper, authors present a novel strategy for improving the sensitivity of SPR immunosensing using streptavidin-biotinylated antibody complex. It is proven that the amplification strategy causes a dramatic improvement of the detection sensitivity. This amplification strategy is based on the construction of a molecular complex between streptavidin and biotin labeled protein. The complex can be formed in a crosslinking network of molecules so that the amplification of response signal will be realized due to the big molecular size of complex.