Electrochemical aptasensor based on g-C3N4/rGO nanocomposite modified electrodes for antibiotics detection in raw milk.

The presence of antibiotics in water environments, dairy products, foods, and beverages is a cause for concern due to its contribution to antimicrobial resistance, which possesses a significant challenge to healthcare management. In line with sustainability development goals, there is a need for rapid and selective methods to detect antibiotics in food. In this study, aptamer immobilized graphitic carbon nitride/reduced graphene oxide (g-C3N4/rGO) nanocomposite modified electrodes have been developed as a platform technology for bio-electrochemical detection. The technology was evaluated for three structurally different antibiotics: oxytetracycline (OTC), ampicillin (AMP), and neomycin (NEO). The g-C3N4/rGO nanocomposite was characterized for its physico-chemical properties using Powder X-ray Diffraction (PXRD), Field Emission Scanning Electron Microscope (FE-SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and its electrochemical properties using Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV). After immobilizing the aptamers on the g-C3N4/rGO surface, the bio-conjugation was confirmed using CV and DPV techniques. The linearity ranges for OTC, AMP, and NEO were established as 4.6-36.8 μg/kg, 1-40 μg/kg, and 10-400 μg/kg, respectively. The apparent recovery of the method was also established through spiking studies conducted on milk samples for 100 μg/kg (NEO), 10 μg/kg (AMP), and 50 μg/kg (OTC). Overall, this study presents a promising g-C3N4/rGO nanocomposite-based platform technology for the detection of antibiotics in food, contributing to the regulatory control of antibiotics and addressing the challenge of antimicrobial resistance. The g-C3N4/rGO nanocomposite material can be explored for other antibiotics with specific aptamers.