Influence of the lengths of thymine, cytosine, and adenine stretches onthe two-dimensional condensation of oligodeoxynucleotides at mercuryand silver amalgam electrode surfaces

Journal: Journal of Electroanalytical Chemistry
Authors: Hasoň S., Pivoňková H., Fojta M.
Year: 2019
ISBN: 1572-6657/


Two-dimensional (2D) condensation of nucleic acid components at mercury electrodes around the potential ofzero charge has been known for decades. In our previous pilot study, we reported on 2D condensation ofhomopyrimidine oligodeoxynucleotides (ODNs) at the hanging mercury drop electrode (HMDE) in negative po-tential region. In this work we focused in detail on the effect of the homopyrimidine ODN length (from 3- to 50-mers) on the formation and properties of 2D condensedfilms at the HMDE. To elicit possible orientation of thehomopyrimidine ODN molecules in their 2D condensed layers (i.e.surface concentration of the ODN moleculesand the cross-section areas per adsorbed ODN molecules) we used a model in which the maximum surface con-centration of the adsorbed ODN molecules is determined from linear dependences of the square of capacitancepit width on temperature. Effect of the length of homoadenine ODNs on their adsorption/desorption processeswere studied for comparison, as well as effects of ionic strength and base protonation. Further we focused onthe effects of the length of periodically repeated homothymine/homocytosine stretches in 30-mer ODNs ontheir interfacial behavior at the negatively charged HMDE. Experiments with binary mixtures of non-complementary and complementary 15-mer homo-ODNs revealed dominance of the homopyrimidine, particu-larly cytosine, ODN responses in such competitive arrangement. The usefulness of solid silver amalgam electrodefor this type of studies is demonstrated. Finally, potential applications of our results in label-free electrochemicalanalysis of alternative DNA structures are brieflydiscussed.

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