Interactions of Protein with Grafted Poly(ethylene oxide) Layer in Two Setups: A Molecular Dynamics Simulation Study

Understanding of interactions between proteins and grafted hydrophilic polymer layers is crucial in the search for antifouling materials. Experimental techniques often use an external force that pushes a protein against the polymer-coated surface, which differs from the situation in living systems. The comparison of both setups using atomistic molecular dynamics simulations is provided in this work. Poly(ethylene oxide) (PEO) chains grafted onto graphene at different grafting densities interact with a fragment of C1q protein. At the lowest grafting density, contradictory outcomes are achieved, attributed to the restricted space of C1q near the grafted PEO layer. The most favorable interactions between C1q and the PEO layer are obtained for the medium grafting density. The secondary structure of C1q undergoes changes during its interactions with the PEO layer, including destabilization of β-sheets and formation of 3₁₀-helices. The orientation of C1q anchored to graphene also affects the interactions with the PEO layer.