Analysis of a non-labeling protein array on biotin modified gold surfaces using atomic force microscopy and surface plasmon resonance

Streptavidin was used as a linker protein for binding a second biotinylated protein. To efficiently combine streptavidin without non-specific binding, a well-controlled array of biotin was prepared on a gold surface by a mixed self-assembly method. Two thiol derivatives containing hydroxyl and biotin functional groups, respectively, were used to fabricate the mixed self-assembled monolayer. The antibody was fragmented, modified with biotin, and added to the array on the streptavidin linker layer. Topographical changes to the array surface caused by protein immobilization were demonstrated by applying atomic force microscopy and ellipsometry. The resonance wavelengths of SPR spectra were red shifted according to the increase in thickness of the dielectric layer by protein immobilization.