Development of Fluorescence-Linked Immunosorbent Assay for Paeoniflorin

In this study, we developed a fluorescent immunoassay approach to detect paeoniflorin (PF) using a fluorescently labelled monoclonal antibody. The PF-specific antibody was purified by the caprylic acid-ammonium sulfate method and protein G Sepharose 4 Fast Flow column and then labelled with fluorescein isothiocyanate (FITC). The FITC-labelled monoclonal antibody was highly specific for PF, with less than 0.076 % cross-reactivity to seven structurally related compounds. The FITC-labelled monoclonal antibody was then used to develop an indirect competitive enzyme-linked immunosorbent assay (icELISA) and indirect competitive fluorescence-linked immunosorbent assay (icFLISA), respectively. FLISA is simple, rapid and sensitive, with a 500-fold lower limit of detection (LOD) compared with conventional ELISA. Finally, using a variety of standards, FLISA was validated. We observed a strong correlation between the results determined by either FLISA or conventional HPLC for the quantification of PF levels (R(2) = 0.9927). Collectively, this study shows that the icFLISA method can be successfully applied for the detection and quantification of PF in medicines and biological samples.