Insulin adsorption on crystalline SiO2: Comparison between polar and nonpolar surfaces using accelerated molecular-dynamics simulations

Adsorption of insulin on polar and nonpolar surfaces of crystalline SiO2 (cristobalite and alpha-quartz) is studied using molecular dynamics simulation. Acceleration techniques are used in order to sample adsorption phase space efficiently and to identify realistic adsorption conformations. We find major differences between the polar and nonpolar surfaces. Electrostatic interactions govern the adsorption on polar surfaces and can be described by the alignment of the protein dipole with the surface dipole; hence spreading of the protein on the surface is irrelevant. On nonpolar surfaces, on the other hand, van-der-Waals interaction dominates, inducing surface spreading of the protein. (C) 2017 Elsevier B.V. All rights reserved.