Development of a Fluorescence-Linked Immunosorbent Assay for Baicalin

Previously, we developed an indirect competitive enzyme-linked immunosorbent assay (icELISA) for baicalin (BAL) and used this assay to investigate the pharmacokinetics of BAL in mice. In this study, an anti-BAL monoclonal antibody (MAb) was purified by the caprylic acid method and then labelled with fluorescein isothiocyanate (FITC). Subsequently, an indirect competitive fluorescence-linked immunosorbent assay (icFLISA) was developed to detect baicalin (BAL) using FITC-labelled anti-BAL MAbs. Characterization of the assay demonstrated an effective BAL measurement range of 6.4 ng/mL to 500 μg/mL (R2 = 0.997). The relative standard deviations (RSDs) for both intra-assay and inter-assay repeatability and precision were below 10 %. This icFLISA for BAL is simple, rapid and sensitive, with a 390-fold larger linear range and a 2-fold lower limit of detection (LOD) compared with the previously developed icELISA. We observed a strong correlation between the results determined by the icFLISA and icELISA methods. Overall, this study provides a useful method for detecting BAL in medicines, enabling in vivo visualization research.