A free-standing flexible sensor MnO2–Co/rGO-CNT for effective electrochemical hydrogen peroxide sensing and real-time cancer biomarker assaying

Research on flexible biosensors is mainly concentrated on their application in acquiring information on physical signals including temperature, pH, and so on. However, there are hardly any studies on using flexible biosensors for assaying biomolecules and biomarkers caused diseases. Herein, a free-standing flexible sensor is designed for H2O2 sensing and cancer biomarker assaying, in which reduced graphene oxide and carbon nanotubes (rGO-CNT) flexible hybrid film is first obtained through self-assembly, then MnO2 nanoflowers and Co nanospheres are anchored on rGO-CNT by electrodeposition. rGO-CNT has good flexibility and conductivity. MnO2 uniformly distributed on rGO-CNT has excellent catalytic performance towards H2O2. Co not only improve the conductivity, but also supply a second active material for H2O2 sensing. Profiting from these advantages, MnO2–Co/rGO-CNT sensor shows an expanded detection range, high sensitivity, low detection limit, excellent repeatability, reproducibility, stability and selectivity. Surprisingly, it can maintain 100% of the original signal after folding 100 times, indicating deformation stability. Moreover, it can real-time monitor H2O2 released by HepG2 cells. The strategy of introducing flexible substrate material and transition metals as well as transition metal compounds provides new insight into the design of flexible electrodes and greatly promote the development of real-time detection of cancer biomarkers.