Probing Förster Resonance Energy Transfer in Carbon Quantum Dots for High-Sensitivity Aflatoxin B1 Detection

Carbon quantum dots (CQDs), with their remarkable optical properties such as strong fluorescence and biocompatibility, are emerging as versatile tools in biosensing and food safety monitoring. This study investigates binding-induced Förster resonance energy transfer (FRET) between CQDs as donors and aflatoxin B1 (AFB1), a highly toxic mycotoxin, as the acceptor. Spherical CQDs, averaging 4.56 nm in diameter and emitting fluorescence at 455 nm, were synthesized for this purpose. Fluorescence spectroscopy, incorporating Stern-Volmer analysis and time-resolved lifetime measurements, revealed the critical role of FRET in this interaction. The estimated Förster radius (R₀) of 4.81 nm and donor-acceptor separation distance (r) of 5.12 nm corresponded to a FRET efficiency of 46%. The observed decrease in donor fluorescence lifetime further supports the FRET mechanism. Selectivity experiments confirmed the system's specificity for AFB1 detection, with a limit of detection (LOD) of 0.439 nM. These findings underscore the potential of FRET-based CQD systems for sensitive and selective AFB1 detection, highlighting their versatility in fluorescence-based sensing applications and their promise for rapid food safety monitoring.