pH Feedback Lifecycles Programmed by Enzymatic Logic Gates Using Common Foods as Fuels

Artificial temporal signaling systems, which mimic living out-of-equilibrium conditions, have achieved tremendous progress in design and preliminary autonomous materials applications. Nevertheless, artificial systems programmed by enzymatic reaction networks in multicomponent and unknown environments, and using biocompatible components remain a challenge. Herein, we demonstrate an approach to program temporal pH signals by orchestrating a tandem of a lag-free YES gate and an enzymatic NAND gate. The NAND gate is realized by an enzymatic disaccharide-to-monosaccharide-to-sugar acid reaction cascade catalyzed by two metabolic chains: invertase-glucose oxidase and β-galactosidase-glucose oxidase, respectively. Lifetimes of the transient pH signal can be programmed from less than 15 min to more than 1 day. We study enzymatic kinetics of the reaction cascades and reveal the underlying regulatory mechanisms. By operating with all-food grade chemicals and coupling to self-regulating hydrogel, we showcase that our system is quite robust to work in a complicated medium with unknown components and in a biocompatible fashion.