Synergy between nanozymes and natural enzymes on the hybrid MoS2 nanosheets/graphite microfiber for enhanced voltammetric determination of hydrogen peroxide

A biosensor for hydrogen peroxide (H2O2) has been developed based on the use of MoS2 nanosheets and graphite that are assembled to form a microfiber hybrid structure. The MoS2 nanosheets are synthesized in situ on a graphite microfiber. The chemical composition and surface morphology of the microfiber hybrid structure has been characterized. The microfiber is shown to display peroxidase-mimicking activity. In the next step, horseradish peroxidase, methylene blue, and chitosan are co-immobilized on the microfiber electrode. The use of MoS2 nanosheets warrants high electrochemical activity of immobilized enzyme on the electrode surface. The modified microfiber electrode, best operated at a voltage of -0.3 V (vs. Ag/AgCl), can be used to sense H2O2 with a linear response in the 0.1 to 90 mu M concentration range and with a determination limit of 30 nM (at S/N=3). The good response is attributed to the synergistic enhancement of the synthetic nanozymes (few-layered MoS2 nanosheets) and immobilized natural horseradish peroxidase (HRP).