Computer Simulations Of Protein Adsorption On Titanium Dioxide And Graphite Surfaces

The interactions between materials and biological molecules such as proteins, have greatsignificance in biological detection, sensor design, and biomaterials. After the protein adsorbson a surface, their interaction will cause the change of protein structure and its performance,which lead to different experimental results. Therefore, the study on the interactions betweenthem is necessary for the application of protein adsorption. However, current studies on themechanism of interactions between proteins and surfaces are deficient in the molecular level.This study mainly explores the adsorption mechanism of several proteins on titanium dioxide,the modified surface and the graphite surface. Those proteins are commonly used in theexperiments. Rutile is adopted in this thesis because it is the most stable crystal form oftitanium dioxide.Due to the good biocompatibility and high dielectric constant of rutile, it is widely usedin sensor design, medical transplant and other fields. Myoglobin is a common protein forelectrode modification. The different crystal faces of rutile have a certain influence on proteinadsorption. After80ns molecular dynamics simulation, the HEME prosthetic group ofmyoglobin is near the rutile (001) and away from rutile (110). The secondary structure ofmyoglobin does not change too much. As for the hydrophilic rutile, two water layers form onboth crystal faces.The excellent properties of composite materials composed of graphene and titaniumdioxide are applied in many fields. The titanium dioxide modified by the graphene canstrengthen interactions between proteins and surfaces. Fibronectin adsorbs on rutile surfacesmodified by different graphene layer. The specific recognition site of fibronectin faces towardthe solution when it adsorbs on23%graphene layer modified rutile surface, which isconductive to the identification of integrin. The adsorption energy of fibronectin on differentsurfaces reduces with higher surface graphene composition. Graphene modification canpromote the fibronectin adsorption on rutile surfaces.In addition, this thesis also studies the mutant myoglobin adsorption on a graphitesurface. The graphite is a common electrode material. Through the mutation of some aminoacids, the hydrophobicity of the protein surface could be adjusted. Simulation results show that the mutant myoglobin has a relatively favorable orientation on the graphite surface. Thestructure of mutant myoglobin does not change too much after the simulation. Mutantmyoglobin would achieve the stable adsorption state quickly because of the increase of thehydrophobicity.