Computer Simulations Of Protein Adsorption On Mono-molybdenum Disulfide Surface

Two-dimensional molybdenum disulfide?MoS₂?has attracted intense interest owing to its unique properties and promising biosensor applications.To develop effective biocompatible platforms,it is crucial to understand the interactions between MoS₂ and biological molecules such as proteins,but little knowledge is known about the orientation and conformation of proteins on the MoS₂ surface at the molecular level.In this dissertation,the adsorptionorientationandconformationoflysozyme,hydrophobinand?-chymotrypsin??-ChT?on MoS₂ surfaces were investigated by molecular dynamics?MD?simulation approach.The major findings of this dissertation are as follows:Firstly,the lysozyme with six different orientations adsorbed on the MoS₂ surface was studied by MD simulations.Simulation results show that lysozyme tends to adsorb on the MoS₂ surface with an“end-on”orientation,indicating that this orientation is favorable for stable adsorption.The end-on orientation could be further categorized into“bottom end-on”and“top end-on”orientations.The driving forces responsible for the adsorption were dominated by van der Waals interactions and supplemented by electrostatic interactions.Further,the conformations of the lysozyme adsorbed on the MoS₂ surface were basically preserved.This simulation study promotes the fundamental understanding of interactions between MoS₂ and proteins and can guide the development of future biomedical applications of MoS₂.Nextly,hydrophobin with orientations that hydrophobic dipole and electric dipole facing and away from the surface respectively adsorption on the MoS₂ surface was studied by MD simulations.The simulation results indicated that hydrophobin adsorbed on MoS₂ surface with a preferential adsorption orientation driven by its hydrophobic dipole,with its hydrophobic patch pointing towards the surface.In the adsorption process,the nonpolar groups of hydrophobin can firmly bind to MoS₂ to expose polar groups in water,facilitating the effective exfoliation of single-layer MoS₂ nanosheets induced by protein in aqueous solution.Futhermore,the native structure of hydrophobin is well preserved during the adsorption.This work lead to a conclusion that hydrophobin can be a promising bio-tool for advantageous production of other TMD materials and promote the exploitation of their various biomedical applications.Finally,?-chymotrypsin??-ChT?with orientations that electric dipole facing and away from the MoS₂ surface was studied by MD simulations.The simulation results show that ChT adsorbs on the surface of MoS₂ with the?-helix?165-172?close to the surface.The van der Waals interaction dominates the driving force of ChT adsorption on the surface of MoS₂,and electrostatic interaction is an important supplement.In the 100ns MD simulation,ChT retained its structure after adsorption on the MoS₂ surface.In the simulation,the distance between the active site of ChT and the surface was moderate,and no active site was completely close to the surface.This may reflect the early stages of adsorption behavior.