Development of quantum dot-based tetrodotoxin immunochromatographic test strips and the effect of different aquatic product matrices on detection results

Tetrodotoxin (TTX) is a highly potent marine neurotoxin that can cause fatal poisoning. It is found not only in pufferfish but also in other marine organisms such as shellfish. In recent years, the number of poisoning incidents due to the accidental consumption of TTX-containing aquatic products has increased. Therefore, the development of a rapid and sensitive TTX assay is urgently needed. In this study, quantum dot-based fluorescent lateral flow immunochromatographic test strips (LFICS) were developed, and the effects of different aquatic matrices on the assay were investigated. The fluorescent probe was synthesized by coupling a monoclonal antibody against TTX with carbonylated quantum dots, and the conditions for strip preparation were optimized. The results of the developed test strips could be observed within 15 min, with a visual detection limit (VDL) of 500 ng/mL and an instrumental detection limit (IDL) of 8.7 ng/mL. The linear range of detection (DLR) was 5–1000 ng/mL. The intra-assay and inter-assay coefficients of variation for the LFICS were 2.15 %–13.71 % and 2.7 %–14.55 %, respectively. Five aquatic samples (pomfret, cod, whelk, clam, and South American white shrimp) spiked with TTX were analyzed using the developed LFICS. The average recoveries ranged from 76 % to 96 % at spiked concentrations of 100 ng/mL and 1000 ng/mL, and from 47.97 % to 94.87 % at a spiked concentration of 10 ng/mL.