ИСТИНА

The analysis of specific nucleic acids sequences is of central importance in clinical medicine because of their use for rapid diagnosis of infectious diseases. Detection of bacterial, fungal, or viral pathogen by modern gene-based techniques usually includes a nucleic acid amplification step. However, a variety of electrochemical sensing techniques has been developed that are achieving levels of sensitivity that make amplification unnecessary [1]. DNA sensors require an immobilization of single-stranded DNA onto electrode surface. Usual carbodiimide coupling chemistry is not fully chemoselective in aqueous solvents. Moreover, hydrolysis occurs, thereby lowering the efficiency of the immobilization. To overcome these drawbacks post-functionalization of a novel conducting poly(azidomethylethylenedioxythiophene) (azido-PEDOT) by “click” chemistry with various types of terminal alkynes can be done [2]. Here we present electropolymerization of azidomethyl substituted PEDOT. Screed-printed electrodes were modified in acidic aqueous solution (in contrast to the most of works presenting substituted EDOT polymerization from organic solvents) in potentiodynamic regime. Increase in oxidation current at maximum anodic potential together with increase in charge upon cycling indicated the conducting polymer formation. Since most of the approaches of nucleic acid detection rely on redox labels or mediators, the electrochemical activity of modified electrodes was assessed. Cyclic voltammetry of ferri-/ferrocyanide redox couple was used for investigating of the electrochemical kinetics of the novel material. Comparison of azido-PEDOT with PEDOT revealed the improved charge transfer of the former resulting in amplified analytical signal (electrochemical rate constant increased by 2 times) and higher faradaic/non-faradaic currents ratio. Thus, azido-PEDOT was electropolymerized from aqueous solution for the first time. The material exhibits enhanced electrochemical kinetics compared to unsubstituted PEDOT. This approach allows improving the sensor performance since the sensitivity of nucleic acid detection methods is mainly driven by the translation of an interfacial layer change into the electrical current. References [1] Labib M., Sargent E.H., Kelley S.O. Electrochemical Methods for the Analysis of Clinically Relevant Biomolecules. Chem. Rev. 2016, 116, 9001−9090 [2] Bu H.B., Götz G., Reinold E., Vogt A., Schmid S., Blanco R., Segura J.L., Bäuerle P. Chem. Commun., 2008, 0, 1320-1322 Acknowledgements This work was supported by Russian Science Foundation (grant no. 18-73-00264).