Dynamic Study On The Interaction Between Nanoparticles And Cell Membrane

In recent years,nanomaterials with outstanding physical and chemical properties have been widely used in biomedicine and other fields.In the meanwhile,the negative biological effects brought by nanomaterials have to be considered.Both the positive application of nanomaterials and the mechanism of biological toxicity of nanomaterials are closely related to the dynamic of nanoparticles in cell membranes.There have been abundant relevant reports.Previous studies focused on the movement of single kind of nanomaterials within cell membranes.The report about the differences between the dynamic of nanomaterials with different dimensions or different sizes in cell membranes is rare.This thesis aims at revealing the dynamic mechanism of nanomaterials in cell membrane.Three kinds of carbon nanomaterials were selected for simulation study from the perspective of material size and dimension.The advantages of carbon nanomaterials such as small size,unique optical properties and higher specific surface area make them excellent in drug delivery and biosensing.The study of dynamic behavior of carbon nanomaterials with different dimensions in cell membranes is of guiding significance for the design and optimization of nanomaterials drug carriers.Based on Stokes-Einstein equation,Green-Kubo relationship and fluid mechanics,the dynamic behaviors of fullerene with different sizes and carbon nanospheres with different dimensions in cell membranes has been studied,and the relationship between the dynamic difference between different carbon nanomaterials in cell membrane were revealed.The main research content of this thesis include:（1）The dynamic behavior of fullerenes with different sizes in membrane and water environments was studied.Due to the elasticity of cell membrane,the velocity autocorrelation function of fullerenes of different sizes in membrane environment exists negative,and the negative autocorrelation degree decreases with the increase of fullerenes size.In other words,the influence of membrane elasticity on translational diffusion of fullerene decreases with the increase of fullerene size.Due to the complexity of cell membrane,the translational diffusion coefficient of fullerene increases first and then decreases with the increase of fullerene size.It is found that with the increase of the size of fullerenes,the effect of film viscosity on the rotational diffusion of materials becomes stronger,and the time required for materials to get rid of the initial rotation state increases.The rotational diffusion coefficient decreases monotonically with the increase of the size of fullerenes.（2）The translational and rotational diffusion kinetics of carbon nanomaterials with different dimensions in cell membrane and water environment were investigated.The translational diffusion of the three carbon nanomaterials in the membrane showed short-time sub-diffusion characteristics.In addition,the velocity autocorrelation function of carbon nanomaterials in membrane environment also exists negative.For translational diffusion,the graphene sheet with the largest contact area with the membrane environment has the slowest translational diffusion and the longest momentum relaxation time.Fullerene C₂₄₀,which closer to the loose tail of the phospholipid molecule,has the fastest translational diffusion.Due to its unique spherical structure,fullerene C₂₄₀has the highest rotational diffusion coefficient in both membrane and water environments.Because of the influence of dimension and membrane complexity,the autocorrelation function of the graphene sheet and the nanotube in the direction parallel to the tube decreases very slowly.During the simulation time of 500 ps,the rotation correlation decreased by only 0.5%～1%.