Metal-doped carbon dots as peroxidase mimic for hydrogen peroxide and glucose detection

Carbon dots (CDs) have several superior characteristics including sufficient carbon sources, easy preparation, no toxicity, and high catalytic efficiency as a new kind of nanozyme. Herein, Ce-doped carbon dots (Ce-CDs), Cr-doped carbon dots (Cr-CDs), Cu-doped carbon dots (Cu-CDs), Fe-doped carbon dots (Fe-CDs), Mn-doped carbon dots (Mn-CDs), and non-metal-doped carbon dots (0-CDs) were synthesized to explore the detection of hydrogen peroxide (H₂O₂) and glucose as peroxidase mimic. The prepared CDs could efficiently oxidize the colorless 3,3',5,5'-tetramethylbenzidine (TMB) into blue oxTMB in the presence of H₂O₂. After adding glucose oxidase (GOD) to the CDs/TMB system, a colorimetric method for glucose detection was developed. The results show that Fe-CDs possess the highest catalytic activity. When using Fe-CDs as peroxidase mimetics, the detection limit of this assay for glucose was 0.029 mmol L^-1. This successfully provides a sensitive and selective colorimetric method for hydrogen peroxide and glucose determination.