A single stimulus leading to multiple responses is an essential function of many biological enzymatic reaction networks, which enable complex life activities. Owing to the lack of allosteric regulation of natural enzymes, it is challenging to duplicate a similar network using non-living chemicals. Herein, we report a nanozymatic cascade reaction network that demonstrates multiple responses of different modes and intensities upon a single H2O2 stimulus based on a single-atom nanozyme (Co-N-CNTs). Taking the two-electron cascade oxidation of 3,3’,5,5’-tetramethylbenzidine (TMB) as an example, the endogenous product H2O2 competitively inhibited substrates in the first one-electron oxidation at the Co-N4 active site on Co-N-CNTs, while accelerated the second one-electron oxidation under a micellar nanozyme. Using such a nanozymatic network, the feedback and feedforward regulation of product transformation were further applied to microfluidic flow reactors as a cell mimic. Owing to the unique varieties of response in intensities and modes, the proposed cell mimic demonstrated highly selective recognition and linear perception of H2O2 against over 20 interferences in a wide range of concentrations (0.01-100 mM), reminiscent of a primordial life-like process in mutable and harsh conditions.
Updated viewpoint, illustrations, and discussions.