Switching biomimetic hydrogels

Abstract

We propose a new strategy for precise, rapid, quantitatively predictable and reversible on-off regulation of enzymatic reactions. Specifically, we report reversible photo and pH-switchable hydrolytic activity of a chymotrypsin mimic. The switching-off of mimic activity when exposed to UV irradiation is a consequence of deswelling of the hydrogel that results in a 25-fold decrease in the diffusivity of the substrate in the hydrogel. The hydrolytic activity of the enzyme mimic can also be switched on/off in response to pH. Unlike native chymotrypsin, which is irreversibly deactivated, the activity of the mimic is reversible and also more stable in hostile environments. A reaction-diffusion analysis of the problem predicts the course of switching quantitatively.