Modulation of solid-water-peptide interfacial properties towards surface adsorption/bioresistance

Controllable protein adsorption on solids is of great importance in many modern technological applications. The role of the water phase in mediating the protein-surface interactions, however, still remains poorly understood. Herein, we employ free energy calculations to systematically explore the mechanisms of the surface adsorption/bioresistance correlating with the interfacial water layers. The studied peptide shows strong binding affinity with the hydrophobic surface, as illustrated by a monotonic decrease in the free energy profile with no energy barriers. However, the surface bioresistance could be triggered in two distinct ways, by not only an enhancement of the surface-water interactions, but also increased interactions between the water and adsorbates. The enhanced surface-water interactions decrease the tendency of the surface dehydration and the subsequent adsorbate penetration into the surface-bound water layers, thus leading to the surface bioresistance. On the other hand, the enhanced water-adsorbate interactions could promote water stabilization of the adsorbate in the bulk solution, effectively preventing the peptide adsorption. Our results further elucidate that the increase in the peptide size favors its adsorption on the hydrophobic surface, but go against the adsorption on the hydrophilic surface. The mechanisms revealed here may facilitate the design of novel proteins/peptides, materials, and solvents for a controllable adsorption at a solid-water interface.