Interfacial Regulation of ZIF-67 on Bacteria to Generate Bifunctional Sensing Material on Chip for Qualifying Cell-Released Reactive Oxygen Species.

Cell's activities are highly dependent on signal molecules, of which reactive oxygen species of the superoxide anion (O 2 •- ) and hydrogen peroxide (H 2 O 2 ) are important ones that always work together to regulate biological processes such as apoptosis and oxidative stress. It is of significance to realize simultaneous qualification of O 2 •- and H 2 O 2 but it still faces challenges particularly in live-cell assay with a complex environment. We report the design of a bifunctional sensing material by interfacially regulating ZIF-67 on bacteria Shewanella putrefaciens to generate cobalt nanoparticles/nitrogen-doped porous carbon nanorods (Co/N-doped CNRs) and its sensing chip for qualifying cell-released O 2 •- and H 2 O 2 . Co/N-doped CNRs exhibit unique properties including porous structure for significantly increased reaction surface area and coordinating Co nanoparticles for rich active sites. The bifunctional Co/N-doped CNRs is used to fabricate the electrochemical sensing chip, which achieves a fast response time (0.5 s for O 2 •- , 1.9 s for H 2 O 2 ), a low detection limit (0.69 nM for O 2 •- , 2.25 μM for H 2 O 2 ), and a remarkably high sensitivity (792.30 μA·μM -1 ·cm -2 for O 2 •- , 153.91 μA·mM -1 ·cm -2 for H 2 O 2 ), among the best of reported bifunctional nanozymes.