中文摘要：

采用全原子分子动力学模拟方法研究了纤连蛋白（FN）在金红石表面、23%石墨烯覆盖率的金红石表面、92%石墨烯覆盖率的金红石表面、石墨表面的吸附行为. 模拟结果表明：FN在金红石表面吸附不稳定. 通过石墨烯修饰二氧化钛表面可降低金红石表面的亲水性；当表面含有石墨烯层时，FN都将稳定地吸附在表面上. 在23%石墨烯覆盖率的金红石表面上，FN的特异性识别位点朝向溶液而有利于整合素识别. DSSP分析结果显示在40 ns的分子动力学模拟过程中，FN的七个β-折叠结构在所有体系中均没有发生太大变化. 由于有石墨烯层存在，表面附近水分子层密度减小. FN的表面吸附能随着表面石墨烯覆盖率的增加而增大. 石墨烯修饰能加强二氧化钛表面对蛋白质的吸附. 本工作可以为移植体修饰生物材料设计与开发提供参考.

英文摘要：

Fibronectin （FN） could be used to modify the transplant of titanium dioxide. However, the hydrophilicity of titanium dioxide may prevent the stable adsorption of protein. Suitable hydrophobic modification of the surface can promote protein adsorption. In this work, all-atom molecular dynamics （MD） simulations were used to study the adsorption of FN on rutile surface, 23% graphene layer modified rutile surface, 92% graphene layer modified rutile surface and the graphite surface. The graphene layer can change the surface chemistry of rutile and break the strong interactions between rutile and water molecules. Parallel tempering Monte Carlo algorithm was used firstly to identify the global-minimum-energy orientation of FN. Subsequently, the orientation and conformation of adsorbed FN on modified titanium dioxide surfaces were studied by MD simulations. The simulation results show that FN can hardly adsorb on the rutile surface. Graphene layer deposited on titanium dioxide can reduce the surface hydrophilicity. When the rutile surface is covered by the graphene layer, FN adsorbs on the surface stably. The specific recognition site of FN faces toward the solution when FN is adsorbed on 23% graphene layer modified rutile surface, which is conducive to the identification of integrin. However, if too much graphene layer deposited on rutile, the specific recognition site of FN would get close to the surface due to the stronger adsorption. The minimum distance between FN and various surfaces can indicate the stability of protein adsorption on surfaces. DSSP analysis shows that the seven β-sheets of FN do not change much in all systems during the 40 ns MD simulations. Due to the deposition of graphene layer, the density of water molecules near the surface decreases. The adsorption energy of FN on different surfaces increases with higher surface graphene composition. Graphene modification could promote the fibronectin adsorption on rutile surfaces. This work can provide some guidance for the design and development o