Design of a Facile Fluorescent Nano-Sensor Using Nitrogen and Sulfur Dual Doped Carbon Quantum Dots for Carbendazim Detection: A Turn-Off-On Approach for Food Safety and Environmental Monitoring.

Carbendazim (CBZ), a widely used agricultural fungicide, poses significant health risks due to its potential for endocrine disruption, infertility, and liver damage. Ensuring food safety and compliance with environmental regulations necessitates sensitive and reliable detection methods. This study introduces a novel, ultrasensitive CBZ detection strategy using nitrogen and sulfur co-doped carbon quantum dots (N-S@CQDs) as fluorescent nanosensors. These N-S@CQDs are synthesized via an environmentally friendly hydrothermal process, utilizing citric acid and thiourea as precursors. The detection platform operates through a "turn-off-on" fluorescence mechanism. Initially, Fe³⁺ ions quench the fluorescence of N-S@CQDs, which is then restored upon CBZ binding. This system achieves an ultralow detection limit of 27.84 ng/mL and a linear response range of 0-100 ng/mL, making it ideal for trace-level analysis in food bioscience applications. The sensor was validated on real food samples, yielding impressive recovery rates of 96.9 to 99.36%. The method demonstrates excellent selectivity, rapid response, and cost-efficiency, making it a powerful tool for real-world applications. This study not only advances the field of CBZ detection but also opens doors to safer, more sustainable practices in agriculture and food safety. The developed method offers a sustainable and cost-effective solution for monitoring CBZ residues in food safety programs and environmental surveillance initiatives, addressing critical challenges in pesticide detection.