Controlling protein retention on enzyme-responsive surfaces.

The ability to change the properties of solid surfaces on demand is a key component of a multitude of established and emerging technologies. Stimuli that have previously been used to trigger changes in surface properties include changes in solvent, light, pH, ionic strength, temperature and magnetic or electric fields. We are interested in developing surfaces that can be triggered by the catalytic action of enzymes. We demonstrate the selective protease (alpha-chymotrypsin and thermolysin) catalysed peptide hydrolysis of surface-tethered fluorenylmethoxycarbonyl-dipeptides. We highlight some of the challenges evident from surface analysis in overcoming enzyme retention to the surface addressed by physical adsorption of soluble PEG(200) to the surface prior to enzyme exposure. Analysis by ToF-SIMS and XPS shows that alpha-chymotrypsin is deposited and retained on the surfaces and that thermolysin, a much more stable enzyme, selectively cleaves the tethered peptides as intended, and is removed from the surface by washing.