[Development of a lateral flow dipstick immunoassay for rapid detection of ginsenoside Re]

A sensitive antibody-based lateral flow dipstick was developed for ginsenoside Re (GRe) detection. The stick consisted of a sample pad, a conjugate pad, membrane and an absorbent pad. The membrane was coated with two capture reagents, GRe-BSA conjugate and goat anti-mouse antibodies, forming a test line and a control line, respectively. The conjugate pad was saturated with colloidal gold particles coated with affinity purified monoclonal anti-GRe antibody. The visual detection limit was 200 microg x L(-1) of GRe and the reaction time was 10 min. The Panax ginseng roots were identified after these samples (10 mg) were extracted with 5 mL tap water for 30 min at room temperature, and the extracts were tested by the dipsticks and ELISA kit. The true and false P. ginseng could be distinguished with dipsticks. The dipstick could be used to detect the quality of the P. ginseng samples when the extract was diluted 100-folds. The results were compared with those obtained using an indirect competitive enzyme-linked immunosorbent assay (icELISA). The dipstick assay proved to be a sensitive and rapid tool for quality control of P. ginseng.