Super electron transfer channels enable Prussian-blue-like nanocarbon felts for ultrasensitive glucose biosensing...

Fast and reliable direct electron transfer (DET)-based glucose sensors are highly desirable for self-monitoring of blood glucose. However, the practical use of enzymes such as glucose oxidase (GOx) is hindered by the lack of nanostructured materials capable of efficiently extracting electrons from the deeply buried redox centers of GOx. In this work, Fe nanorods embedded within a carbon cubic framework are engineered as super electron transfer channels, enabling ultrafast electron transport. A simple and cost-effective two-step strategy combining hydrothermal synthesis and pyrolysis is developed to achieve a highly efficient DET process. The resulting hierarchical biomass-derived heterostructure, namely Prussian blue-like nanorod felts (PBL-NFs), exhibits a large specific surface area (784.44 m² g^-1), significantly enhancing glucose oxidation response. The optimized biosensor achieves exceptional performance with an apparent electron transfer rate constant (k_s) of 1.06 s^-1, a low detection limit of 3.4 μmol L^-1, a wide linear range of 0.02-12.5 mmol L^-1, and a high sensitivity of 123.28 μA mM^-1 cm^-2. The hierarchical heterostructure enables favorable enzyme orientation via site-specific immobilization, facilitating efficient electrical communication between the GOx cofactor and electrode surface. This work presents a promising effective strategy to enhance DET in biosensing, offering great potential for applications in clinical diagnostics and pathological research.