Protein adsorption studies using surface plasmon resonance
A study was undertaken to investigate the adsorption of two proteins, bovine serum albumin (BSA) and pepsin, to a gold surface using surface plasmon resonance (SPR). The SPR experiment was constructed for the study of fluid samples and the performance of the experiment was evaluated using custom data analysis programs. After characterizing the index of refraction of the thin gold layer using SPR, we measured the adsorption of protein molecules to the gold surface and changes to the protein layers in response to changes in the pH of the buffer solution. As expected from studies of bulk protein solutions, we observed evidence for a reversible conformational change for the BSA layer as well as an irreversible conformational change for the pepsin layer. We find that for both the pepsin and BSA experiments that changes in conformation are impeded by the interaction of the protein with the surface.