Albumin (BSA) adsorption over graphene in aqueous environment: Influence of orientation, adsorption protocol and solvent treatment

We report 150 ns explicit solvent MD simulations of the adsorption on graphene of BSA in two orientations and using two different adsorption protocols, i.e. free and forced adsorption. Our results show that free adsorption occurs with little structural rearrangements. Even taking adsorption to an extreme, by forcing it with a 5nN downwards force applied during the initial 20 ns, we show that, along a particular orientation, BSA is able to preserve the structural properties of the majority of its binding sites. Furthermore, in all the cases considered in this work, the ibuprofen binding site have shown a strong resilience to structural changes. Finally, we compare these results with implicit solvent simulations and find that the latter predicts an extreme protein unfolding upon adsorption. The origin of this discrepancy is attributed to a poor description of the water entropic forces at interfaces in the implicit solvent methods.