Sub-femtomolar capacitance-based biosensing of kanamycin using screen-printed electrodes coated with redox-active polymeric films.

An ultrasensitive capacitance-based biosensor has been developed capable of detecting the kanamycin (KAN) antibiotic at sub-femtomolar levels. The biosensor was constructed using a potential-pulse-assisted method, allowing for the layer-by-layer deposition of a melanin-like polymeric film (MLPF) on an electrode surface modified with gold nanoparticles (AuNPs). The MLPF was formed through the electrochemical polymerization of dopamine and the specific kanamycin aptamer. By optimizing the operating parameters, we achieved a label-free detection of kanamycin by monitoring the variation of pseudocapacitive properties of the MLPF-modified electrode using electrochemical impedance spectroscopy. The developed biosensor demonstrated a wide linear response ranging from 1 fM to 100 pM, with a remarkable limit of detection of 0.3 fM (S/N = 3) for kanamycin. Furthermore, the biosensor was successfully applied to detect kanamycin in milk samples, exhibiting good recovery. These findings highlight the promising potential of the aptasensor for determination of antibiotic residues and ensuring food safety. In conclusion, our ultrasensitive capacitance-based biosensor provides a reliable and efficient method for detecting trace amounts of kanamycin in dairy products. This technology can contribute to safeguarding consumer health and maintaining high food safety standards.