Hydrogen peroxide sensing in body fluids and tumor cells via in situ produced redox couples on two-dimensional holey CuCo2O4 nanosheets.

A novel nanomaterial of two-dimensional holey CuCo2O4 (2D HCCO) nanosheets was synthesized via a general template-directed method and employed for the first time to construct an effective electrochemical platform for H2O2 sensing with the combination of cerium oxide (CeO2). During the electrocatalytic reduction of H2O2, the synergetic catalysis of CeO2/HCCO/MWCNTs/GCE owing to the naturally holey frameworks and the mediator of CeO2 results in the ultra-sensitive detection of H2O2. The current was greatly enhanced owing to the unique holey structure that can minimize the charge transfer distance and provide more active sites to boost the signals, and the dual oxidation state of Ce3+/Ce4+ on the surface of 2D HCCO nanosheets can promote the in situ production of Cu2+/Cu+ and Cu+/Cu and further amplify the detection signal. The CeO2/HCCO/MWCNTs/GCE showed a wide linear range from 1 μM to 7.31 mM using chronoamperometry at the potential of - 0.25 V and a relatively low detection limit of 0.16 μM in physiological environment, which was also utilized for tracking the trace H2O2 released from Hela cells. This study shows great promise for the emerging application of holey HCCO-based biosensors in bioanalysis and early cancer diagnosis. Graphical abstract.