Electrochemical capacitance as a Next-Gen tool for kanamycin detection

Food security is essential for protecting human health; however, the contamination of food and dairy products with antibiotics remains a significant issue. In this study, we developed an innovative capacitance-based aptasensor for kanamycin (KAN) detection by modifying screen-printed electrodes with polyaniline/reduced graphene oxide (PANI/rGO). Electrochemical capacitance spectroscopy (ECS), derived from electrochemical impedance measurements, was successfully used to detect KAN with remarkable sensitivity. Cyclic voltammetry revealed an 85 % decrease in the specific capacitance upon KAN binding, achieving a detection limit of 1.19 fg·mL⁻¹. Further analysis of the ECS data allowed the capacitance response to be deconvoluted into double-layer and redox capacitance components, revealing complex interfacial changes and enabling an even lower detection limit of 0.13 fg·mL⁻¹. Fitting the ECS data to a Langmuir–Freundlich isotherm indicated heterogeneous binding dynamics between the aptamer and KAN. Across a dynamic range of 1 fg·mL⁻¹ to 1 ng·mL⁻¹, this dual-technique approach provided both highly sensitive detection and a detailed mechanistic understanding of the aptamer–KAN interactions. The combination of ultrasensitive performance and mechanistic insight marks a significant step forward in antibiotic monitoring technologies, with direct implications for food safety applications.