Reversible photoregulation of binding of alpha-chymotrypsin to a gold surface

An ability to optically modulate the interactions of surfaces with functional biomolecules provides an important basis for generating new technologies including reversible biosensors, advanced medical implants, and biomolecular computers. Here we report the first example of reversible photoregulation of binding of a protease to a functional surface. A modular approach is presented with a surface-bound inhibitor containing a photoisomerizable azobenzene core to which is attached (i) appropriate protease binding functionality and (ii) a tether for surface attachment. The principle is demonstrated for alpha-chymotrypsin using a phenylalanine-based trifluoromethylketone inhibitor containing an azobenzene core and an alkyne-functionalized ethylene glycol tether, which is attached to the surface using click chemistry. UV/vis irradiation of the functional surface leads to a significant, reversible change in the amount of alpha-chymotrypsin that attaches to the surface, as measured by surface plasmon resonance.