Analysis of protein arrays with a dual-function SPR biosensor composed of surface plasmon microscopy and SPR spectroscopy based on white light

We present a self-developed novel dual-function surface plasmon resonance (SPR) biosensor composed of surface plasmon microscopy (SPM) and SPR spectroscopy based on white light for analysis of protein arrays. SPR images and spectra were obtained from protein arrays under the same measurement environment by the dual-function SPR biosensor installed with a charge-coupled-device camera and a spectrometer on a titled angle plate. A measurable range of the SPM was calculated as approximately the half of the full width at the half maximum of a Cr/Au (3/45 nm) SPR spectrum. Interactions of glutathione surface with glutathione S-transferase fusion proteins on arrays were analyzed by SPR image contrasts of the SPM mode. However, a large SPR signal variation caused by multilayered proteins, which was in part analyzed by the SPM mode, was fully analyzed by the SPR spectroscopy mode of the dual-function SPR biosensor. Thus, the novel dual-function SPR biosensor is a useful system for high-throughput analysis of biomolecular interactions on protein arrays in a label-free format.