High peroxidase-like activity of iron and nitrogen co-doped carbon dots and its application in immunosorbent assay

Herein, iron and nitrogen co-doped carbon dots (Fe-N-CDs) were synthesized through a solvothermal method assisting with the microwave synthesis system for the first time. Multiple techniques were employed to characterize the properties of the obtained particles. The emphasis of current work was the confirmation of their intrinsic peroxidase activity due to the Fe doping, which is similar to natural ferriporphyrin. Through catalyzing the oxidization of 3,3',5,5'-Tetramethylbenzidine (TMB) in the presence of H2O2, the Fe-N-CDs exhibited a superior catalytic performance over horseradish peroxidase (HRP), suggesting their potential applications in catalytic area. Furthermore, the Fe-N-CDs were coupled to antibody as the biocatalyst instead of HRP (commonly used in enzyme-linked immunosorbnent assay (ELISA)). Results of carcinoernbryonic antigen (CEA) determination demonstrated the feasibility of this approach, a detection limit as low as 0.1 pg/mL within 5 mm has been achieved. These advances may trigger research interest in Fe-N-CDs and their new applications in various fields.