Interaction of ciprofloxacin with DNA studied by spectroscopy and voltammetry at MWCNT/DNA modified glassy carbon electrode

The interaction of ciprofloxacin (Cf) with double-stranded DNA was studied by cyclic voltammetry, fluorescence emission spectroscopy, and UV-Vis spectroscopy. The presence of DNA results in a decrease in the current and a positive shift in the Cf oxidation peak indicates the intercalative interaction. The corresponding heterogeneous rate constant (k(s)) and the electron transfer coefficient (alpha) were calculated for free Cf and the bound Cf-DNA complex. The UV spectroscopic data confirmed the interaction between Cf and DNA is intercalative. Besides, the fluorescence emitted by Cf at 420 nm could be quenched in Britton-Robinson (B-R) buffer solution (pH 7.0, 0.04 mol L-1) when DNA was added. The mechanism of fluorescence quenching was a static quenching; the binding constant and numbers of binding sites were obtained from the Stern-Volmer plot. The calibration curve was found to be linear between F-0/F and the DNA concentration is lied in the two dynamic ranges of 0.8-96.0 and 96.0-223 mu g mL(-1) with the detection limit of 0.33 mu g mL(-1). The method was efficaciously applied to analyze DNA in the serum sample. (C) 2012 Elsevier B.V. All rights reserved.