A dual-functional fluorescent sensor based on a single soybean-derived carbon dots for discrimination and quantification of tetracyclines in food.

This work presents a simple and sustainable platform for antibiotic monitoring in food, based on a single type of soybean-derived nitrogen-doped carbon dots (N-BCDs). The excitation-dependent fluorescence of the N-BCDs enables dual functionality. First, as a single-wavelength probe, it achieves sensitive quantification of individual tetracyclines in milk, with a low limit of detection (0.12 μM for TC) and excellent recoveries (97.2-110.4%). Second, and more innovatively, it transforms into a dual-wavelength array sensor by leveraging differential responses at two optimized wavelengths. This allows for the discrimination of three structurally similar tetracyclines (TC, DC, OTC) in chicken samples with perfect accuracy, addressing a key challenge in multiplexed detection. The platform's multifunctionality is further highlighted by its demonstrated biocompatibility and pH-responsive drug release. This strategy provides a versatile and effective tool for simultaneous detection and discrimination of antibiotic residues in complex food matrices.