Cu2O-mediated assembly of electrodeposition of Au nanoparticles onto 2D metal-organic framework nanosheets for real-time monitoring of hydrogen peroxide released from living cells.

The development of metal nanoparticles (MNP) combined with a metal-organic framework (MOF) has received more and more attention due to its excellent synergistic catalytic ability, which can effectively broaden the scope of catalytic reactions and enhance the catalytic ability. In this work, we developed a novel ternary nanocomposite named Cu2O-mediated Au nanoparticle (Au NP) grown on MIL-53(Fe) for real-time monitoring of hydrogen peroxide (H2O2) released from living cells. First, Cu2O-MIL-53(Fe) was prepared by redox assembly technology, which provided the growth template, and active sites for AuCl4-. Au@Cu2O-MIL-53(Fe)/GCE biosensor was prepared by further loading nano-Au uniformly on the surface of Cu2O by electrochemical deposition. Compared to individual components, the hybrid nanocomposite showed superior electrochemical properties as electrode materials due to the synergistic effect between AuNPs, Cu2O, and MIL-53(Fe). Electrochemical measurement showed that the Au@Cu2O-MIL-53(Fe)/GCE biosensor presented a satisfactory catalytic activity towards H2O2 with a low detection limit of 1.01 μM and sensitivity of 351.57 μA mM-1 cm-2 in the linear range of 10-1520 μM. Furthermore, this biosensor was successfully used for the real-time monitoring of dynamic H2O2 activated by PMA released from living cells. And the great results of confocal fluorescence microscopy of the co-culture cells with PMA and Au@Cu2O-MIL-53(Fe) verified the reliability of the biosensor, suggesting its potential application to the monitoring of critical pathological processes at the cellular level.