Electrochemical and spectroscopic studies of the interaction of antiviral drug Tenofovir with single and double stranded DNA. 
In the present study, the electrochemical behavior of the antiviral drug tenofovir (tnf) on a boron-doped diamond electrode (BDDE) has been studied using square-wave voltammetry (SWV).  The experimental conditions such as the supporting electrolyte composition and the SWV parameters were optimized.  Under the optimized conditions, a simple and sensitive SWV procedure for tnf determination was developed in the concentration range of 5.0 × 10-6 to 1.0 × 10-4 mol L-1.  The calculated limit of detection and limit of quantification were equal to 5.6 × 10-7 and 1.9 × 10-6 mol L-1, respectively.  The biological significance of the developed method was demonstrated by a quantitative analysis of the pharmaceutical formulations Viread and Tenofovir disoproxil Teva.  Moreover, both voltammetric and spectroscopic techniques were used to study the interaction between tnf and DNA.  Changes in the electrochemical and spectroscopic behavior of tnf in the presence of DNA were used to calculate the binding constants of the formed complexes.  The estimated values of Gibbs free energy revealed that the formation of the drug-DNA complexes was a spontaneous and favorable process.  Moreover, for free and bound tenofovir, kinetic parameters such as heterogeneous rate constant, electron transfer coefficient, and diffusion coefficient were determined.