Asymmetrically coordinated single-atom iron nanozymes with Fe-N₁C₂ structure: A peroxidase mimetic for melatonin detection

Owing to the unique coordination environment and high atom utilization efficiency, single atom catalysts have been considered as an ideal artificial enzyme to mimic natural enzymes. Herein, single-atom Fe nanozyme anchored on N-doped Ti₃C₂T_x (Fe SA/N-Ti₃C₂T_x) with asymmetrically coordinated Fe-N₁C₂ configuration is synthesized by vacancy capture and heteroatom doping strategy, which exhibits excellent peroxidase-like activity. Based on the results of peroxidase catalytic kinetics and X-ray adsorption fine spectroscopy, the Fe-N₁C₂ active sites in Fe SA/N-Ti₃C₂T_x are responsible for the excellent performance. Furthermore, the developed Fe SA/N-Ti₃C₂T_x can be employed to quantitative detection of melatonin (MT), which shows a wide linear detection range (0.01–100 μM) and an excellent detection limit (7.3 nM) in buffer, 0.01–100 μM and 7.8 nM in serum samples. Our work proves that MXene-based single atoms can be promising nanozyme in the field of bioassays.