Fe-N/C nanozyme with specifically boosted peroxidase-like activity for ultrasensitive colorimetric bioanalysis

In the field of analytical spectroscopy, nanozymes have a wide range of possible uses. Herein, annealing was used to create a Fe-N-doped carbon (Fe-N/C) nanozyme that is abundant in functional Fe-Nx structural domains. Further experimental analysis revealed that the Fe-N/C nanozyme possessed catalytic activity and substrate affinity comparable to that of natural horseradish peroxidase (HRP) and can catalyze chromogenic substrate in the presence of hydrogen peroxide (H2O2), accompanied by the production of colored oxidation products. Based on the reduction of ascorbic acid (AA), which could inhibit the oxidation of the chromogenic substrate and result in a decrease in the system's absorbance intensity, ultrasensitive colorimetric biosensing for AA determination was established. The outcomes demonstrated a wide linear range (0.1 µM to 160 µM), low detection limit (0.03 µM, 3 s/k), and favorable anti-interference ability. Finally, this sensor was successfully applied to actual samples with recoveries in the range of 92-106%, demonstrating satisfactory practicability. This approach will, most importantly, serve as a foundation for the development of high-performance colorimetric sensors, opening new avenues for bioanalysis and safety monitoring.