Understanding the Effects of Temperature on Electrostatic DNA Denaturation

In this work, the electrostatic denaturation of 18-bp DNA duplexes was investigated via Square Wave Voltammetry (SWV) to determine the extent of melting (∆) and rate of melting (). Electrostatic denaturation was observed over the temperature range of 20-50 °C, and purely electrostatic melting was defined from 27.5°C. In contrast, electrostatic denaturation for 30 °C was defined as a mixture of thermal melting thiol desorption + electrostatic melting. Electrostatic denaturation is a temperature-dependent process, and the amount of melting of the dsDNA increased with temperature. It was also observed that the ∆ and values increase with temperature further supporting the claim that electrostatic denaturation is a temperature dependent process. Therefore, the melting rate is a temperature-dependent process, while the extent of melting is a temperature-independent process for temperatures below the melting point of the dsDNA. Since the melting rate is a temperature-dependent process, the data collected followed Arrhenius\u27s behavior but did not follow Van\u27t Hoff\u27s behavior. Additionally, the activation energies calculated were significantly lower than the activation energy for free DNA in solution. These lower than expected activation energies are most likely due to the crowding of negatively charged phosphates on the electrode surface, the application of an applied potential to induce DNA melting, and the potential of not having free DNA in solution