Development of immunoassay methods based on monoclonal antibody and its application in the determination of cadmium ion.

Owing to the threat of cadmium (Cd2+) to public health, it is an urgent demand to develop effective, sensitive, and rapid methods for the detection of cadmium. In this study, indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and immunochromatographic test strips (ICTS) were established for the determination of Cd2+ based on the obtained mAb with high specificity and high affinity (Kaff = 3.0 × 109 L/moL). The linear range of ic-ELISA detection was 0.03-1.11 ng/mL and 50% inhibitive concentration (IC50) of cadmium ion was determined to be 0.15 ng/mL. The visual limit of detection (vLOD) of the AuNS-based strip was 0.375 ng/mL. The vLOD of AuNF-based strip using higher intensity reporter determined to be 0.03 ng/mL, which was enhanced 12 times compared to the traditional strip. In summary, the developed immunoassays based on mAb shows great potential for monitoring the cadmium ion in environmental samples.