Effect of Ectoine on the Conformation and Hybridization of dsDNA in Monolayer Films: A Spectroelectrochemical Study

Abstract

AbstractLack of long‐time stability of dsDNA‐based supramolecular assemblies is an important issue that hinders their applications. In this work, 20 base pairs long dsDNA fragments [(dCdG)20‐65 %] composed of 65 % dCdG and 35 % dAdT nucleotides were tethered via a thiol to the surface of a gold electrode. The self‐assembled (dCdG)20‐65 % monolayer was immersed in solutions containing ectoine, a compatible solute. Electrochemical results showed that these monolayers were stable for one month. In situ IR spectroscopy indicated that ectoine interacts weakly with the phosphate‐ribose backbone, dehydrating the phosphate groups and stabilizing the A‐DNA conformation. This structural reorganization led to a reorientation of nucleic acid base pairs and a local disruption of the double‐helix structure. However, the conformation and orientation of the dsDNA fragment was stable in the −0.4<E<0.3 potential range. As a direct interaction between ectoine and dsDNA, the enzymatic reaction of exonuclease VII hydrolyzing the ester phosphate bond in ssDNA, was blocked. We show that the addition of a compatible solute to the electrolyte solution stabilized the dsDNA structure despite structural rearrangements.