A monoclonal antibody against testosterone was produced and used to construct an indirect enzyme-linked immunosorbent assay (ELISA) and immunochromatographic assay. As testosterone could not be linked to the protein directly, testosterone and methyltestosterone were first derived by using carboxymethoxy lamine hemihydrochloride (CMO) to introduce a carboxyl group at the carbonyl group position. Then the resulting testosterone-3-CMO was coupled to the carrier protein to form the immunogen, using the 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)/N-Hydroxysuccinimide (NHS) method. A cell line obtained by cell fusion secreted an antibody which showed high affinity with testosterone. Based on methy ltestosterone-3-CMO-ovalbumin (OVA) as the competitive antigen, the ELISA we developed showed high sensitivity to testosterone, with IC 50 of 0.11 ng/mL. The results of cross-reactivity testing showed that the antibody was specific to testosterone. Based on this antibody, an immunochromatographic assay was developed and used to detect testosterone in milk samples. This method could be used as a fast and cost-effective alternative tool for screening for endocrine-disrupting compounds.

A novel and highly sensitive immunochromatographic strip based on a monoclonal antibody (3A9) was developed for the detection of cadmium in tap water. The 50% inhibition concentration of the antibody, which showed no cross-reactivity with other heavy metal ions, was 0.45 ng/mL and it recognized Cd(II)-1-(4isothiocyanobenzyl) ethylenediamine-N,N,N ′ ,N ′ -tetraacetic acid (EDTA) (Cd(II)-ITCBE) and not metal-free ITCBE and EDTA. The cutoff value for semi-quantitative detection of the strip was 5 ng/mL and the lower limit of detection for quantitative detection was 0.2 ng/mL using a scanning reader. The percent recovery ranged from 107.6% to 132% in tap water samples.

In this study, we developed an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and an immunochromatographic strip assay based on a monoclonal antibody (mAb) against methylmercury (MeHg) to detect the presence of MeHg in tap water. Under optimum conditions (pH 8.0, 0.8% NaCl, and 0.1% Tween 20), the 50% half maximal inhibitory concentration (IC 50) and limit of detection (LOD) were 16.64 and 2.03 ng/mL, respectively. The anti-MeHg mAb was specific to mercury with no cross-reactivity with other metal ions. The cutoff value of the immunochromatographic strip assay was 500 ng/mL for semiquantitative detection, and the LOD was 11.3 ng/mL for quantitative detection. The average recovery rates of the ic-ELISA and immunochromatographic strip assay were 98.13% and 107.87%, respectively, in tap water. Therefore, ic-ELISA and the immunochromatographic strip assay can be used to detect MeHg in tap water.