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 (O2 center dot-) and hydrogen peroxide (H2O2) 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 O2 center dot- and H2O2 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 O2 center dot- and H2O2. 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 O2 center dot-, 1.9 s for H2O2), a low detection limit (0.69 nM for O2 center dot-, 2.25 mu M for H2O2), and a remarkably high sensitivity (792.30 mu A center dot mu M-1 center dot cm-2 for O2 center dot-, 153.91 mu A center dot mM-1 center dot cm-2 for H2O2), among the best of reported bifunctional nanozymes.