Résumé
A competitive electrochemical immunosensor based on the nano-composite material immobilization and enzymatic amplification was designed for detection of microcystin-LR. Gold nanoparticles/carboxylated multi-walled carbon nanotubes (AuNPs/c-MWCNTs) composite film, which formed by electrodepositing of AuNPs on the C-MWCNTs modified glassy carbon electrode,was used for the immobilization of the antibody of microcystin-LR (anti-MCLR). Horseradish peroxidase (HRP) was introduced onto the nanocomposite interface by HRP blocked sensing interface and specific capture of antibody with target. It could be employed to catalyze the reduction of H2O2, and to block the possible remaining active sites as well. A competitive immunoreaction between antigen and MCLR-HRP was used for target analysis. In the presence of H2O2and hydroquinone (HQ),MCLR could be indirectly detected with differential pulse voltammetry (DPV) method by determining the reduction current of HQ. Under the optimal conditions, the proposed immunosensor exhibited wide linear ranges in the concentration ranges of 0.1-100.0 μg/L, with a detection limit of 0.038 μg/L (S/N = 3,n=8). The immunosensor showed good specificity, stability and sensitivity. It was used to determine MCLR in real water samples with the recoveries of 72.9%-117.3%.