Effect of Graphene Oxidation Rate on Adsorption of Poly‐Thymine Single Stranded DNA

In order to understand how oxidation rate of graphene surfaces affects single‐stranded poly‐thymine, poly(T) 20 , structure during physisorption, all‐atom molecular dynamics simulations are performed. In aqueous solutions, poly(T) 20 is a complex structure with stacked and coiled regions. However, on the graphene surfaces, there are three different regimes for the adsorption process, which heavily depends on the surface oxidation: (1) on pristine graphene or graphene oxide (GO) with low oxygen coverage (GO 5%) the stacked poly(T) 20 structure becomes unfolded due to formation of strong π–π interactions with the surface, (2) on graphene oxide with moderate oxygen coverage (GO 10%–25%) the structure of poly(T) 20 is well preserved because of the balance between van der Waals and electrostatic interactions, and (3) on graphene oxide with high oxygen content (GO 30%–60%) stacked poly(T) 20 structure is locally disrupted due to formation of strong hydrogen bonds with the surface. Moreover, surface roughness due to the presence of oxygen groups plays a pivotal role in structural retention of poly(T) 20 by preventing its nucleobases from forming π–π stacking interactions with the surface.