AuNPs-LISA, an efficient detection assay for Opisthorchis viverrini (Ov) antigen in urine

The enzyme-linked immunosorbent assay (ELISA) is currently a powerful technique for the detection of Opisthorchis viverrini antigen (OvAg) in urine samples. However, its sensitivity and analysis time need to be improved. In the present study, we aimed to improve the signal enhancing system of traditional ELISA by using gold nanoparticles (AuNPs) with peroxidase-like activity on its surface instead of the horseradish peroxidase (HRP) system. The catalytic activity of the AuNPs probe can be boosted by the gold enhancing solution and the addition of ATP. The catalytic ability of the AuNPs probe depended on the probe and the H₂O₂ concentration. The proposed approach can reduce the number of the traditional ELISA steps with better detection sensitivity. Interestingly, the limit of detection (LOD) of the test was 23.4 ng mL^-1, substantially lower than the 93.8 ng mL^-1 for the traditional ELISA. The AuNPs-LISA assay showed higher sensitivity and specificity, 93.81% and 91.34%, respectively, compared to the traditional ELISA. The proposed assay was successfully applied for the detection of OvAg in urine samples. This will provide an effective tool for the detection, control and elimination of human opisthorchiasis.