The Production Of Immunochromatographic Stripe Of Methamphetamine

Gold Immunochromatographic Assay is a one-step immunoassay in which the drug or metabolite competes with the immobilized drug conjugate in the test area for the limited colloidal gold-labeled antibody complex in which the stripe is made to screen the drug abuser.The test device consists of a membrane strip and the methamphetamine-BSA conjugate has been immobilized on it. A colloidal gold-labeled antibody complex is dried at one end of the strip. If there isn't any methamphetamine or metabolite in the urine sample, the colloidal gold-labeled antibody complex moves with the urine by capillary action to contact the immobilized methamphetamine ?BSA conjugate. An antibody-antigen reacts and forms a visible line in the "test" area. It is indicative of a negative result. When methamphetamine presents in the urine sample, the drug or metabolite will compete with the immobilized drug conjugate in the test area for the colloidal gold-labeled antibody complex. If the amount of drug is sufficient, the drugs will react with most of the gold-labeled antibody complex, thus preventing the labeled antibody to contact with the drug conjugate. A color band (line) in the test area will be invisible and it is indicative of a positive result.A negative urine will produce two colored bands, and a positive sample will produce only one band. The control line is not influenced by the presence or absence of drug in the urine, and therefore, should be present in all reactions.Colloidal gold, which diameter is about 27nm , is obtained by reducing the gold chloride with sodium citrate, and labels Methamphetamine monoclonal antibody. The optimum pH for labeling is between 6.5-7.5, and the amount of monoclonal antibody is 20μg/ml. The glass fibre and nitrocellulose (NC) ofMillipore are used as chromatographic materials, in which the antigen and sheep anti-mouse IgG are coated at 0.2mg/ml, the colloidal gold-labelled antibody is sprayed with 30μl/cm2.This method has a sensitivity of 1000ng/ml, specificity100%,and without cross-reaction with some drugs. The results can be read clearly in 5 minutes.