Dual-signal ratiometric electrochemical aptasensor based on COFs-derived Fe/N-doped porous carbon and methylene blue-enriched COFs for sensitive and accurate detection of kanamycin

Kanamycin (KAN), a veterinary antibiotic, often leads to residue pollution in food, thereby threatening human health. Therefore, we established a dual-signal ratiometric electrochemical aptasensor for KAN detection in food. Herein, a ferrocene-functionalized COFs-derived Fe/N-doped porous carbon was synthesized and served as splendid electrode material to generate amplified electrocatalytic signal toward hydroquinone (HQ). Tetrahedral DNA-supported aptamer probes were employed to improve binding affinity and reduce nonspecific adsorption. Methylene blue-enriched COFs (MB@SA-COFs) were designed as another signal tag to generate an effective MB signal. With the recognition of KAN, the MB@SA-COFs would detach from electrode surface, inducing a decreased MB signal and decreased resistance, thereby causing an increased HQ signal. The signal on-off mode was conducive to mitigating environmental interference through self-calibration. Consequently, the aptasensor showed a wide linear range and a low detection limit for KAN detection. Satisfactory applicability was observed in milk samples, demonstrating its practicability for food safety monitoring.