Immunochromatographic assay for miroestrol and deoxymiroestrol, its cross-reactivity, and application in Pueraria mirifica (white Kwao Krua) analysis

IntroductionMiroestrol (Mi) and deoxymiroestrol (Dmi) are trace, yet potent, phytooestrogens found in white Kwao Krua [Pueraria candollei var. mirifica (Airy Shaw & Suvat.) Niyomdham, PM]. However, the analysis of these substances is difficult because of complex matrix effects and their various analogues. In addition, alteration in the cross-reactivity of a gold nanoparticle (AuNP)-based immunochromatographic assay (ICA) resulting from the electrostatic adsorption between antibodies and AuNPs has not yet been evaluated. ObjectivesThis study aims to develop, characterise, and validate ICA with a monoclonal antibody exhibiting similar reactivity against Mi and Dmi (MD-mAb). Materials and MethodsThe ICA performance was validated for cross-reactivity and performance in comparison with those of indirect competitive enzyme-linked immunosorbent assays (icELISAs) with MD-mAb and mAb exhibiting specificity against Mi (Mi-mAb). ResultsThe ICA showed a limit of detection (LOD) at 1 and 16 mu g/mL for Mi and Dmi, respectively. The cross-reactivity of the ICA with Dmi was lower (6.25%) than that observed with the icELISA (120%). Cross-reactivity of ICA against other compounds of the PM was also correlated with those of icELISA; no false-positive/negative results were observed. The repeatability and reproducibility of the ICA were confirmed. The results obtained using ICA in samples of PM are correlated with the concentrations determined through icELISAs. ConclusionAn ICA with MD-mAb was constructed and validated. However, direct conjugation via the electrostatic adsorption of mAb-AuNPs was expected to alter the cross-reactivity of ICA, especially that of the analyte analogue Dmi.

Automated summary

This study developed and validated an ICA with a monoclonal antibody exhibiting similar reactivity against Mi and Dmi. The ICA showed a LOD at 1 and 16 mu g/mL for Mi and Dmi, respectively. The cross-reactivity of the ICA with Dmi was lower than that observed with the icELISA, and the cross-reactivity of ICA against other compounds of the PM was correlated with those of icELISA.