Purpose: Sensitive and selective point-of-care biosensor is an urgent pursuit of serological antibody detection to control parasite pathogen. For specific, quantitative and on-site screening of Trichinella spiralis  infection in livestock, a quantum dot nanobead-monoclonal antibody (QB-mAb) probe-based immunochromatographic assay (ICA) was developed by introducing a competitive sandwich strategy (QB-CICA).
Methods: In the QB-CICA, QB-mAb probes competed with serum antibody for a particular epitope, followed by immunocomplexes binding to capture antibody on the test line. With the accumulation of target antibody, captured probes served as signal elements for fluorescent readout in a “turn off” mode, along with the fluorescence gradually weakened. The sensitivity and standard calibration curve of the QB-CICA were quantified using swine sera as negative control (n = 200) and artificial infected swine sera (n = 80) compared with a commercial ELISA kit. Besides, Trichinella spiralis -antibody targeting test ability of the QB-CICA, instead of other parasites or viruses antibodies (n = 10), was evaluated.
Results: The QB-CICA exhibited a good linear range, a low detection limit of 189.92 ng mL^{− 1} and 100% selectivity that was higher than commercial ELISA kit (90%), as well as the same serological positive rate (100%) with commercial ELISA kit in different infection dose models.
Conclusion: Taking advantage of its simplicity, short response time (25 min), sensitivity and specificity, the proposed QB-CICA has potential applications for parasite-related antibody monitoring in food safety and clinical diagnosis fields.
Keywords: rapid serological antibody test, competitive sandwich immunochromatographic assay, quantum dot nanobead, Trichinella spiralis