Abstract

This study presents the development of a cost-effective and sustainable electrochemical aptasensor based on the covalent immobilization of an aptamer on carbonized and oxidized eggshell membranes (CESM-OX) for detecting carbendazim (CBZ) in an aquatic environment. Key experimental conditions were optimized for the sensor's performance, including aptamer concentration, immobilization time, and CBZ recognition time. The aptasensor demonstrated excellent selectivity and stability, achieving a detection limit of 0.686 mu g/L in Milli-Q water and 0.400 mu g/L in a simulated secondary effluent without standard addition methods. The aptasensor maintained high specificity for CBZ, even in the presence of common interferents such as atrazine, glyphosate, trifluralin, and benomyl. The stability test revealed that the aptasensor maintained consistent performance for up to 7 days when stored at 4 degrees C, with minimal variation in current response. Validation complex of the aptasensor using real wastewater matrices revealed a strong correlation (Pearson coefficient of 0.9993, relative error lower than 5 %) between the aptasensor and the reference technique, UHPLC, underscoring the aptasensor's high accuracy and reliability. Notably, no pre-treatment of samples was required, making the aptasensor sustainable for application in intensive agricultural areas where the highest concentrations found were 6000 ng/L. The aptasensor utilizes CESM-OX as a base material, offering an eco-friendly alternative by upcycling waste while maintaining sensitivity and stability, even in real complex matrices, which makes the aptasensor a valuable tool for environmental monitoring and detecting contaminants of emerging concern (CECs).