Converting dual quenching into a ratiometric signal: a supramolecular fluorescent sensing pair for NIT detection

Developing ratiometric fluorescent probes targeted at detecting nitroxynil (NIT) residues in food matrices carries critical implications for safeguarding food safety and public health. Nevertheless, it still poses a considerable challenge to construct such NIT-oriented ratiometric fluorescent probes that can deliver stable signal outputs. In the present study, we introduce an innovative ratiometric fluorescent sensing platform that is built upon a set of albumin-based host-guest systems. By precisely adjusting the ratio of the two albumin-based host-guest complex (FLO@ALB and FLC@ALB) as a pair of sensing elements, we successfully constructed a test system that enables rapid (< 5 s) and reliable ratiometric response toward NIT. This newly developed approach shows remarkably superior specificity for NIT against a range of other possible interfering substances, delivering a low detection limit at 0.762 μM. Furthermore, the real-world application feasibility of this method has been verified through the quantitative detection of NIT in actual food matrix samples. Acceptable spike recoveries spanning from 89.30% to 118.74% were acquired across the detection process, with all relative standard deviation (RSD) values maintained below 5.02%. Correspondingly, the limits of detection (LODs) for NIT in beef and milk samples were determined to be 1.038 μM and 1.219 μM, respectively. These results demonstrate that the developed strategy holds great promise for routine monitoring of NIT residues in complex food products.