Application of spectral SPR imaging for the surface analysis of C-reactive protein binding

Abstract

We investigated the surface characteristics of antibody binding on protein chips with resonance wavelength-based spectral surface plasmon resonance (SPR) imaging. The fluctuation of the resonance wavelengths for gold and dithiobis (succinimidyl propionate) (DTSP) array spots were less than 0.4 nm, which was good enough to analyze biomolecular interactions on the arrays. A serial process of biomolecular interactions from gold to anti-C-reactive protein (CRP) on the protein chips was monitored by the spectral SPR imaging. SPR images showed that distribution of anti-CRP binding onto the CRP surface was not uniform. Changes of color in the two-dimentional SPR images were explained by variations of the refractive index caused by differences in the amount of bound anti-CRP on protein chips. These results suggest that the spectral SPR imaging can be used as a novel tool for the analysis of surface distribution of protein binding with a label-free format.