Electrochemical biosensor based on gold nanoflowers-encapsulated magnetic metal-organic framework nanozymes for drug evaluation with in-situ monitoring of H2O2 released from H9C2 cardiac cells

A novel electrochemical biosensor was fabricated for the determination of hydrogen peroxide (H2O2) by electro-deposition of gold nanoflowers (AuNFs) on molybdenum disulfide (MoS2) nanosheets-supported magnetic metal-organic framework (MMOF) Fe3O4@ZIF-8 hybrid nanozymes. Fe3O4@ZIF-8 nanomaterial was selected on account of the high peroxidase-mimicking activity of magnetic Fe3O4 nanoparticle and the large pore size and surface area of metal-organic framework ZIF-8. However, we found that the MMOF Fe3O4@ZIF-8 nanomaterial was easily dissoluted into the electrolyte solution followed by an unreproducible electrochemical response. MoS2 nanosheets and one-step electrodeposition of gold nanostructures can largely enhance the long-term stability, conductivity and catalytic performance. With the help of MoS2 nanosheets and electrodeposited gold thin layer, it can have an important impact on the retaining of surface states of Fe3O4@ZIF-8 nanomaterials to keep the electrocatalytic activity. The obtained hybrid nanocomposites (AuNFs/Fe3O4@ZIF-(8)-MoS2) exhibited prominent electrocatalytic activity for the reduction of H2O2 and the fabricated biosensor detected H2O2 with a low detection limit of 0.9 mu M and an ultra-wide linear detection range of 5 mu M-120 mM. Moreover, this electrochemical biosensor was successfully performed to detect H2O2 concentration released from H9C2 cardiac cells under drug stimulation. These results indicated that this modified electrode can serve as a general and powerful platform to detect other disease biomarkers for drug evaluation.