Molecular Dynamics Simulation Of The Interaction Between Surface Modified Biomaterials And Protein Macromolecules

The interaction between biomacromolecules and the surface of bio-medical material directly influence biocompatibility of the material. But the mechanism of this interaction is poorly understood yet because of its complicacy. To the aspect of anticoagulant biomaterials, according to the hypothesis of "Keeping Natural Behavior", a series of different zwitterionic surface structures modified materials were prepared. And they demonstrated good blood compatibility in experimental study. But the validity of the hypothesis is still needed to be testified through the interactions between the zwitterionic surface and blood proteins on the molecular level.In order to explain how different surface structures influence the biocompatibility of material in physical environment, we choose the γ-Fg of fibrinogen and a-hemoglobin segment of hemoglobin as research objects to simulate the interactions between protein and different surface modified polyurethane material surfaces in the Implicit Solvent Model Generalized Born model. Molecular dynamics simulations are performed using the leap-frog algorithm of CHARMM force field in the NVT ensemble. The simulations run for10ns or5ns of simulated time, and all bond lengths are constrained with a time step of2fs. Energy minimizations are performed on each system using the Steepest Descend and Conjugate Gradient methods. All simulations were performed with Materials studio4.4(MS4.4) and discovery studio2.1(DS2.1) software package (Accelrys, USA) on a constant temperature of310K. Meanwhile, the molecular dynamics simulations of the separate protein fragment system was performed as the natural state of the protein, which was used to compare with the results of proteins contacting with polyurethane. Through the analysis of relevant parameters, the feasibility of " Keeping Natural Behavior " was furtherly verified.The results of the dynamics simulations show that the zwitterionic and hydrophilic surfaces behave the best to keep the natural behavior of the protein.