Single-Atom Fe/Au Nanozymic Electrode to Accelerate Glucose Oxidation for Self-Powered Sensing

Self-powered sensing based on enzymatic biofuel cells (EBFCs) provides a promising platform for miniaturized and portable exosome analysis by converting biochemical reactions directly into electrical output. However, the operational reliability of such systems remains fundamentally restricted by the instability, limited electron-transfer efficiency, and high cost of natural enzymes. Herein, we design a heteroatomic nanozyme featuring Fe single atoms electronically coupled to Au nanoparticles anchored on nitrogen-doped carbon (FeSA-AuNP/NC) to enhance glucose oxidation. When paired with a FeSA/NC cathode, FeSA-AuNP/NC serves as an efficient nanozymatic anode to construct a fully nanozyme-driven BFC. The fully nanozymic BFC displays markedly higher electrical output and improved operational durability relative to the BFC using a GOx-based bioanode. As a proof of concept, this fully nanozymatic system enables quantitative and sensitive exosome detection across a wide linear range (10³-10⁷ particles mL^-1) with an ultralow detection limit of 362 particles mL^-1, highlighting the promise of electronically regulated interfaces to advance next-generation self-powered biosensing platforms.