Voltammetric Study of dsDNA Modified by Multi-redox Label Based on N-methyl-4-hydrazino-7-nitrobenzofurazan

• nitrobenzfurazan increases signal response diversity of DNA electroanalysis.
• sensitive detection of the NBF labeled DNA and its constituents at m-AgSAE.
• nitrobenzfurazan provides possibility to use a signal switch on/off techniques.
• m-AgSAE offers advantageous properties for subsequent biosensor development.

Voltammetric behaviour of novel synthetic multi-redox DNA label N-methyl-4-hydrazino-7-nitrobenzofurazan (NBF), a deoxycytidine monophosphate conjugate with NBF via formylthiophene linker (dCNBFMP), and NBF labeled model short double stranded DNA (dsDNA-NBF) were systematically studied at mercury meniscus modified silver solid amalgam electrode (m-AgSAE) for the first time in this work. Successful enzymatic incorporation of the NBF labeled deoxycytidine triphosphate into the DNA was confirmed and the dsDNA-NBF offered new more positive cathodic signals at −520 mV and −1160 mV, compared to the nucleic acid itself. Used modification resulted in increase of selectivity and sensitivity of the DNA voltammetric determination. Next to the pioneering voltammetric behaviour of all studied compounds at m-AgSAE, electroanalytical methods based on cyclic voltammetry, adsorptive stripping cyclic voltammetry and open circuit transfer stripping cyclic voltammetry were developed for sensitive detection of these (bio)molecules. Furthermore, utilization of variable negative vertex potential and scan rate was also observed and their appropriate selection considerably influenced registered peaks on cyclic voltammograms. These redox processes increased signal response diversity and offered utilization of signal switch on/off technique, as well. Tentative electrochemical reduction mechanisms of the NBF, dCNBFMP and dsDNA-NBF were proposed and discussed, together with possibilities and limitations of the NBF + m-AgSAE system.

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