A series of molecular dynamics simulations were conducted to investigate the interaction between protein (lysozyme) and two typical non-fouling membranes (PDMS and SBMA). Lysozymes were initially put on the surfaces of two non-fouling membranes with a minimal separation distance 0.5 nm

1.0 nm and 1.5 nm. Centroids of proteins were fixed during the first 15 ns simulation to determine the forces that membranes extended on proteins. Then the fix was cancelled in the following 20 ns simulations. At the end of simulations

both the proteins were adsorbed on membranes. By analyzing the types of residues near adsorption sites

contact areas

hydrogen bonds

VDW contacts between protein and membranes

we concluded that PDMS has a better combination with lysozyme than SBMA. This closely adsorption makes the protein not easy to leave from membranes. To fully understand the molecular mechanism of non-fouling materials

the simulation results were analyzed from two aspects: interaction between protein and membrane

interaction between surface hydration layer and membrane. Combined with our previous work which concentrated on properties of surface hydration layers it is concluded: (1) PDMS has a larger attractive force on protein than SBMA at the whole distance range. Both the interactions between protein and membranes were energetically favorable

but Lysozyme interacted much more strongly with PDMS than SBMA. (2) SBMA has plenty of hydrogen bonds

electrostatic interactions

and cage effects with surface waters that lead to a stable surface hydration layer. The hydration layers were believed to form a physical and energetic barrier to prevent protein adsorption on the surface. At last we proposed a possible mechanism of protein adsorption or anti-fouling: the first obligatory step of protein adsorption was the dehydration of both protein and the membrane. After that

protein induced a series of conformation changes to change its surface hydrophobic/hydrophilic properties

charge distributions etc. Then it came to the final stable adsorption state by forming hydrogen bonds

VDW contacts and electrostatic interactions between protein and substrates.