Application of elimination voltammetry to the resolution of adenine and cytosine signals in oligonucleotides II. Hetero-oligodeoxynucleotides with different sequences of adenine and cytosine nucleotides
Elimination voltammetry with linear scan (EVLS) was applied to the resolution of reduction signals of adenine (A) and cytosine (C) residues in short synthetic hetero-oligodeoxynucleotides (ODNs) with different sequences of A and C. T e EVLS evaluation required linear sweep voltammograms measured on a hanging mercury drop electrode (HMDE) at different scan rates. Compared to linear sweep voltammetry (LSV) and usual voltammetric methods the EVLS is capable of resolving the overlapped A and C signals, specifically by using the elimination function which eliminates the charging and kinetic currents (I-c, I-k) and conserves the diffusion current (I-d). Since for an adsorbed electroactive substance this elimination function yields a well readable peak - counterpeak signal, the adsorptive stripping (AdS) procedure was favorably used. The adsorption of ODNs was carried out at -0.1 V for accumulation time of 120 s under stirring. It was found that heights and potentials of LSV signals were affected by ODNs concentrations, pH, scan rates, time of accumulation, and stirring speed during the adsorption. While on LSV curves the only one reduction peak of A and C residues was observed in all ODNs, the EVLS yielded two separated peaks in dependence on A, C sequences and pH. Our results showed that the EVLS in connection with the AdS procedure is a useful tool for qualitative and quantitative studies of short ODNs and a promising sensitive method for the development of electrochemical sensor following the ODN sequences.