Voltammetric studies of the interaction of rutin with DNA and its analytical applications on the MWNTs–COOH/Fe3O4 modified electrode

Multi-walled carbon nanotubes functionalized with a carboxylic acid group (MWNTs–COOH)/iron oxide (Fe3O4) modified glassy carbon electrode (MWNTs–COOH/Fe3O4/GCE) and DNA/MWNTs–COOH/Fe3O4/GCE were prepared. The electrochemical behaviors of rutin (RU) were investigated on MWNTs–COOH/Fe3O4/GCE by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in britton–robinson buffer solution (B–R). The interaction of RU with DNA was also explored. Dramatic decrease of peak current without obvious peak potential shift were observed in both cases of DNA in the solution and immobilized on the electrode surface. In addition, the electron transfer coefficient (α) and the rate constant (ks) kept unchanged in the absence and presence of DNA. So interaction of DNA with RU formed a non-electroactive complex. The binding constant and binding ratio was obtained in the process. The interaction was also confirmed by UV–visible spectroscopy. The reduction peak current was linear with the concentration of RU in the range of 2.50 × 10−8 to 1.37 × 10−6 M, with a detection limit of 7.5 nM. The MWNTs–COOH/Fe3O4/GCE showed comparatively low detection limit, rapid response, simplicity for the determination of RU.