Enzyme-free electrochemical sensor for the determination of hydrogen peroxide secreted from MCF-7 breast cancer cells using calcined indium metal-organic frameworks as efficient catalysts

As a major member of the reactive oxygen species, hydrogen peroxide (H2O2) is a vital endogenous marker for oxidative stress analysis. Herein, we report an enzyme-free sensor for the electrochemical detection of H2O2 based on the electrodeposition of platinum (Pt) nanoparticles (NPs) on calcined metal-organic framework (MOF) MIL-68-NH2 (In) and molybdenum disulfide (MoS2) nanosheets. Firstly, the glassy carbon electrode (GCE) was coated by two-dimensional MoS2 nanosheets, which can load more MOF materials. Interestingly, we have found that calcined MIL-68 (cMIL-68) displays the better catalytic activity than pristine MIL-68 because of the larger surface area and better electrical conductivity. And the cMIL-68 exhibits the best electrocatalytic property for H2O2 after 3 h calcination. To enhance the detection sensitivity, Pt NPs was electrodeposited on the cMIL-68/MoS2/GCE and can offer better electrical conductivity and stability. Therefore, the incorporation of three materials provides the superior selective and sensitive detection of H2O2. Under the optimal conditions, a wide linear range was shown in 10 nM to 18.3 mM and a low detection limit was found to be 6.26 nM. Furthermore, Pt/cMIL-68/MoS2/GCE was applied for real-time quantification of H2O2 released from MCF-7 breast cancer cells. These results suggest that the calcined MOF materials have the great potential for improving the detection sensitivity of sensor in monitoring physiological processes.