Fe,N-doped carbon as peroxidase mimics for single-use colorimetric bioassays

Nanozymes as promising alternatives to natural enzymes have attracted enormous attentions for their high robustness, low cost, and tunable activity. Among various candidates, carbonaceous nanomaterials possess extra advantage features of designable surface properties and good biocompatibility. However, their peroxidase-like activity is typically moderate owing to the short half-life of radical hydroxyl (·OH), the poor catalytic activity and substrate affinity. Herein, we synthesize Fe,N-doped carbon (Fe,N-C-800) via pyrolyzing Fe-doped ZIF-8 (ZnFe-ZIF) in NH₃ at 800 °C. Fe,N-C-800 shows excellent peroxidase mimic with outstanding substrate affinity and catalytic velocity superior to the advanced Fe single-atom catalyst. The excellent enzyme-like performance is ascribed to the synergistic contributions of Fe- and N-doping. Fe functions as catalytic center while pyrrolic N absorbs TMB (3,3’,5,5’-Tetramethylbenzidine) substrate and enhances the electron density of Fe sites, thereby shortening the migration distance of ·OH and further improving the catalytic activity. Based on Fe,N-C-800, disposable paper bioassays are fabricated and exhibit ultrasensitive detection of H₂O₂. Graphical abstract: [Figure not available: see fulltext.].