Surface plasmon resonance imaging measurements of protein interactions with biopolymer microarrays

The surface-sensitive optical technique of surface plasmon resonance (SPR) imaging is an ideal method for the study of affinity binding interactions of unlabeled biological molecules in a multiplexed format. This approach has been widely applied to monitor DNA-DNA, DNA-RNA, peptide-protein, and protein-protein interactions as well as surface enzyme reactions. The success of SPR imaging measurements relies on the robust attachment of biomolecules in an array format. In this chapter, we introduce two different surface attachment chemistries that covalently immobilize DNA and peptides onto gold surfaces through the modification of self-assembled alkanethiol monolayers. Array fabrication approaches for the creation of individually addressable elements through the use of either gold dot patterns or polydimethylsiloxane (PDMS) microchannels are detailed. The utility of SPR imaging for the study of protein interactions is demonstrated with two biological systems: the binding of response regulator proteins, VanR and OmpR, onto a DNA array, and the interaction of S protein with an array of S-peptide variants. Furthermore, the application of real-time SPR imaging to the multiplexed determination of S-protein adsorption/desorption kinetics is described.