Importance of membrane selection in the development of immunochromatographic assays for low-molecular weight compounds

This study was performed to demonstrate the importance of selecting an appropriate membrane when developing immunochromatographic assays (ICAs) for the sensitive detection of low-molecular weight compounds. Based on our findings, we propose a theoretical basis for selecting such a membrane. When eluting the sample solution for the competitive ICA using colloidal gold label for low-molecular analytes, the degree of binding inhibition is proportional to the collision frequency between the antibody-colloidal gold (Ab–CG) and analyte before Ab–CG binding to the capture antigen and a higher concentration of pesticides around the Ab–CG leads to a greater degree of inhibition. Therefore, we propose that the relative migration speed of the analyte and Ab–CG on the test strip is critically important for selecting a membrane in the development of sensitive competitive ICAs. We developed a novel method to estimate such a relative migration speed. We demonstrated the applicability of this proposal by using it to select an appropriate membrane for the development of an ICA of the pesticide diazinon.

Graphical abstractDesirable membrane for competitive immunochromatography.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Membrane selection for competitive immunochromatographic assay (ICA) is discussed. ► Relative migration speed of analyte and antibody-colloidal gold (Ab–CG) is important. ► For lateral flow ICAs, analyte moving slightly faster than Ab–CG is desirable. ► For dipstick ICAs, analyte moving much faster than Ab–CG is desirable. ► The proposal was useful in membrane selection for ICA of the pesticide diazinon.