Computer Simulations of Fibronectin Adsorption on Graphene Modified Titanium Dioxide Surfaces

Abstract

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 of modified implant biomaterials.

Adsorption of Hydrophobin on Different Self-Assembled Monolayers: The Role of the Hydrophobic Dipole and the Electric Dipole

“…Molecular dynamics (MD) simulations are well-suited to the study of orientation and conformation change of proteins/peptides adsorbed on solid surfaces and could provide molecular level details. ,,− ,− In this work, the adsorption of a class II hydrophobin (HFBI) on four different types of SAM surfaces will be investigated through a combined parallel tempering Monte Carlo (PTMC) and all-atom MD simulation approach. These SAMs are terminated with the methyl (−CH 3 ), hydroxyl (−OH), carboxyl (−COOH), and amino (−NH 2 ) groups and represent hydrophobic, hydrophilic, negatively charged, and positively charged surfaces, respectively.…”

Replica-Exchange Molecular Dynamics Simulation of Basic Fibroblast Growth Factor Adsorption on Hydroxyapatite

“…Protein–surface interactions are a fundamental issue in various fields and devices. The orientation of an adsorbed protein on a medical device, for example, greatly determines the activity of the protein. − Molecular simulation is well-suited to provide insight about protein behavior on a surface. Simulating a protein–surface system is usually computationally expensive because of the complexity of proteins and the huge number of water molecules, which makes the adsorption energy landscape rugged.…”

“…FigureS10in the Supporting Information. Unlike the highly ordered water layer on a TiO 2 surface,26,51,52 the water molecules adsorb more freely on the HAP surface. In 200 ns CMD, bFGF adsorbs around 0.35−0.37 nm above the HAP surface under weak protein−HAP interactions (approximately −55 kJ•mol −1 ) and the orientation converges fast at 0.8−1.0 (see Figures S10−S12 in the Supporting Information).…”