Self-Regulated and Temporal Control of a "Breathing" Microgel Mediated by Enzymatic Reaction.

Naturally occurring systems have the ability to self-regulate, which plays a key role in their structural and functional adaptation. The autonomous behavior in living systems is biocatalytically controlled by the continuous consumption of energy to remain in a non-equilibrium condition. In this work, we show the construction of a self-regulated "breathing" microgel that uses chemical fuels to keep the system in the out-of-equilibrium state. The enzyme urease is utilized to program a feedback-induced pH change, which in turn tunes the size switch and fluorescence intensity of the microgel. A continuous supply of chemical fuels to the system allows the process to be reversible. This microgel with tunable autonomous properties provides insights into the design of artificial systems and dynamic soft materials.