Self‐Powered Biosensor Driven by a Hybrid Biofuel Cell with CuCoP‐Polyoxometallate Composite as Both Cathode Catalyst and Sensing Interface

Abnormal concentrations of hydrogen peroxide (H₂O₂) are toxic to living cells and may induce a number of diseases. Herein, a self-powered miniaturized biosensor (SPB) based on an enzyme biofuel cell is constructed to monitor H₂O₂. This SPB significantly minimized the use of bioenzymes that often experience instability and lead to the high cost of biosensors. More specifically, a composite of polydopamine (PDA)-gold nanoparticles (AuNPs) is prepared as an anodic catalyst scaffold to immobilize glucose oxidase to efficiently catalyze the oxidation of glucose (fuel) due to its excellent biocompatibility and electrical conductivity. Upon the incorporation of CuCoP with a polyoxometalate H₃PW₁₂O₄₀ (PW₁₂), a nanoenzyme of CuCoP-PW₁₂ composite is realized as a non-biological cathodic catalyst to replace the conventional cathode enzymes for the reduction of H₂O₂. The abundant catalytic active sites on CuCoP-PW₁₂ and high electron transfer rate of PW₁₂ result in a high catalytic activity toward H₂O₂ reduction at the cathode. Owing to a good synergy between the bioanode and abiotic-cathode, the prepared SPB exhibits two linear ranges (2-20 and 20-50 µm) and a low detection limit (0.0589 µm) toward H₂O₂ detection. Upon the use of H₂O₂ as a model analyte, this work demonstrates that SPB can be effectively applied in biomedical sensing.