| As the most direct method of theoretically investigating the behaviors of complex molecular systems, molecular dynamics is very suitable for the simulation of the protein-surface interactions. So we use molecular dynamics software, Discovery Studio 2.1 for the research. In the Implicit Solvent Model-Generalized Born model, we choose the nine peptides segment of coagulation Factor XII and the fibrinogen segment as research objects to simulate the interactions between protein (segment) and surface of polyurethane grafted with hydrophilic groups. In addition, the system of undisturbed protein (segment) is simulated to represent the natural behavior. By using Discovery Studio (DS), some parameters which will change during the interaction between the protein and the surface of the material were calculated. By comparing the relevant parameters, we can obtain the relationship between the composition, structure of the material and conformation changes of adsorbed protein, verify the rationality of the hypothesis of "Keep Natural Behavior", then provide theoretical foundation for designing new anticoagulant polymer materials, selecting methods during materials preparation process and controlling parameters during process procedure.The research provides the details of the protein (segment)-surface interactions on molecular level, and shows the change of the protein (segment) conformation caused by different surface. The results of the dynamics simulations show that the surface of polyurethane grafted with Hydroxyethyl methacrylate (HEMA) behaves the best to keep the natural behavior of the protein (segment) and the optimum grafting degree of the Hydroxyethyl methacrylate group on the polyurethane surface is 75%-100%. Although more complicated blood protein and more hydrophilic surface are still needed to study, this finding could be a good proof of the hypothesis of "Keep Natural Behavior" and have important significance for the further research. |
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