Development Of The Diagnostic Reagent For Human Alpha-Fetoprotein (Colloidal Gold)

AIM To develop a rapid, simple and self-performing gold immunochromatographic assay(GIA) for the detection of human alpha-fetoprotein in serum. METHODS Prepare colloidal gold by reducing agent Na3citrate, then label monoclonal anti-AFP antibody A1 to obtain conjugate pad , Connecting to the sample pad is a nitrocellulose membrane, which contains one line of immobilized monoclonal anti-AFP antibody A2, serving as the test line, and one line of immobilized goat anti-mouse IgG antibody, serving as the control line. Attaching to the other end of the membrane is an absorption paper pad, serving as the sample liquid reservoir. After the addition of a sample to the sample pad, the sample liquid will flow from the sample pad to the conjugate pad, then to the membrane, and finally reach the absorption pad. Initially, a reddish test line on the membrane will become visible if the sample contains AFP. This is due to the fact that AFP in the sample flows through the sample pad and binds the conjugate to form a complex. This complex then migrates down to the membrane and binds to the immobilized anti-AFP antibody A2 of the test line, resulting in the immobilization of the reddish conjugate. If the sample contains no AFP, no conjugate can be immobilized on the membrane and no visible test line will show. Hereafter, the unbound conjugate migrates further on the membrane and binds to the immobilized anti-IgG antibody of the control line. Therefore, the control line will always show after the testing, because the immobilized anti-mouse IgG antibody of the control line can bind all the conjugate it is in contact with, regardless the sample contains AFP or not. RESULTS The sensitivity for AFP's testing is 20IU/ml. A total of 530 serum of patients and healthy people were detected for AFP by GIA and RIA. The specificity and sensitivity of GIA were 99.06% and 99.05%. The corresponding rate of both tests was 99.06%. CONCLUSION GIA is a specific, sensitive, simple and rapid assay for AFP in serum. It has a broad use in human life.