Electrocatalysis of ferricyanide reduction mediated by electron transfer through the DNA duplex: Kinetic analysis by thin layer voltammetry.

DNA-mediated electron transfer (ET) underlies a variety of bioelectronics applications, and, thus, simple approaches for its kinetic analysis are required. Here, electrocatalysis of a ferricyanide reduction catalyzed by methylene blue (MB) bound to either (dGdC) 20 or (dAdT) 25 duplexes tethered to gold via an alkanethiol linker was voltammetrically studied at stationary electrodes, and its kinetics was analyzed by two theoretical models. A thin layer voltammetry analysis, assuming that the reaction occurs within the l -nm thick layer formed by the DNA duplexes of the length l , yielded the electrocatalytic rate constant k 1 of (2.1 ± 0.4)105 and (2.4 ± 0.5)106 M−1 s−1, for (dGdC) 20 and (dAdT) 25. The sequence-specific k 1 values were consistent with structural differences of (dGdC) 20 or (dAdT) 25 at the negatively polarized interface and approached the k 1 previously reported for the rotating disk electrode system (Angew. Chemie Int. Ed. 58 (2019) 3048). These results offer new tools for immediate kinetic analysis of electrocatalytic reactions involving long-range ET along the DNA duplexes, the tools that allow differentiating electrical properties of nucleic acids in the most convenient and simple way. Image 1 • Electrocatalysis of [Fe(CN) 6 ]3- reduction by DNA-bound methylene blue was studied. • Kinetics of electrocatalysis was assessed by thin-layer voltammetry at stationary electrodes. • Theoretical approach allowed evaluation of DNA-mediated electron transfer (ET) rates. • Evaluated reaction rates were consistent with those obtained in the rotating disk electrode system. • Results offer simple tools for kinetic analysis of electrocatalysis involving DNA-mediated ET. [ABSTRACT FROM AUTHOR]