Detection of TMV with ODA-H2O2-HRP voltammetric enzyme-linked immunoassay system

o-Dianisidine (ODA)-H2O2-horseradish peroxidase (HRP) voltammetric enzyme-linked immunoassay system has firstly been used for the detection of tobacco mosaic virus (TMV). HRP catalyzes strongly the oxidation reaction of ODA by H2O2, the product of which produces a sensitive second order derivative linear sweep voltammetric peak at potential of -0.56 V (versus SCE) in Britton-Robinson (BR) buffer. HRP activity has been measured with this voltammetric peak and TMV detected through immunoreaction. The detection limit for HRP is 9.25 x 10(-7) mU l(-1) and the linear range is 2.5 x 10(-6)-5.0 x 10(-4) mU l(-1). The detection limit for the clarified TMV is 0.25 ng ml(-1) and the highest dilution ratio detected for the infected leaf sap is 1:8 x 10(5). The sensitivity for TMV detection with this method is higher than that with the enzyme-linked immunosorbent spectrophotometric assay (ELISA) using ODA-H2O2-HRP system. The processes of the enzyme-catalyzed reaction and the electro-reduction of the product of the enzyme-catalyzed reaction have been described. (C) 1998 Elsevier Science B.V. All rights reserved.