Sensitive detection of a plant virus by electrochemical enzyme-linked immunoassay

The electrochemical enzyme-linked immunoassay increases the sensitivity of the detection of cucumber mosaic virus (CMV) by 5-fold compared with the sp ectrophotometric o-phenylenediamine (OPD) enzyme-linked immunosorbent assay (ELISA). The detection limit for the purified CMV is 1.0 ng/mL and the hig hest dilution ratio of the infected leaf sap is 1:5.0 x 10(4). The method i s based on coupling the oxidation reaction of o-aminophenol (OAP)-H2O2 cata lyzed by HRP-IgG conjugate with the electro-reduction of the enzymatic prod uct. The enzymatic product 2-aminophenoxazine-3-one exhibits a sensitive se cond order derivative linear-sweep voltammetric response at the potential o f -0.65 V (vs. Ag/AgCl) in pH 8.0 Britton-Robinson (B-R) buffer solution. S o it can be applied to the detection of the plant virus with highly improve d sensitivity.