Ratiometric fluorescent nanosystem based on upconversion nanoparticles for histamine determination in seafood.

Histamine is the prime culprit of toxicity resulting from seafood consumption, whereas conventional detection methods are not convenient to meet the needs of rapid histamine analysis nowadays. Based on upconversion nanoparticles (UCNPs) and inner filter effects (IFE), a novel ratiometric fluorescence nanosystem was developed for the efficient detection of histamine. Through pre-treatment with solid-phase extraction (SPE) and colorific azo coupling reaction of histamine, the fluorescence of UCNPs at 548 nm was quenched, while fluorescence at 664 nm was unchanged. Thus, ratiometric fluorescence I548/I664 was inversely proportional to histamine concentration at a wide range of 10-200 mg/L. The detection limit was 7.34 mg/L, one order of magnitude lower than that of the traditional colorimetric method (25 mg/L). In addition, such a convenient and environment-friendly detection system was further employed to quantify the histamine in fish, shrimp, and shellfish samples, showing excellent application potential in seafood safety.