Environmental detection of amoxicillin using a molecularly imprinted graphene oxide-polyethylenimine electrochemical sensor

Amoxicillin (AMX), a widely used β-lactam antibiotic, is frequently detected in surface waters due to its high consumption and limited metabolic degradation. Its environmental presence contributes to the spread of antibiotic resistance and poses risks to aquatic ecosystems and public health, highlighting the need for efficient monitoring tools. In this work, we report the development of a novel, low-cost, and highly selective electrochemical sensor for the indirect detection of amoxicillin, based on a glassy carbon electrode (GCE) modified with graphene oxide (GO) functionalized by a molecularly imprinted polyethyleneimine polymer (GO-MIP). The GO-PEI composite was synthesized via epoxide ring-opening chemistry and imprinted with AMX to generate selective recognition cavities. The sensor's performance was characterized using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The proposed GO-MIP sensor exhibited high sensitivity and selectivity for AMX, with a linear detection range from 10 nM to 1 mM, with a limit of detection (LOD) of 0.52 µM in standard solutions and 5.06 µM in environmental water samples. The proposed sensor represents the first application of a molecularly imprinted polyethyleneimine-functionalized graphene oxide composite for AMX detection. It combines low cost, ease of fabrication, and high selectivity, making it a promising proof of concept platform for environmental monitoring of antibiotic contaminants.