Molecular Dynamics Simulation Of Interactions Between Nanoparticles And Alveolar Surfaces Based On Coarse-grained Methods

With the dawn of nanoscience,the use of nanomaterials has become widespread in various scientific fields from cosmetics and electronics to medicines.While gold nanoparticles have good biocompatibility and easy to carry out surface modification,they are used as drug carriers for the treatment of lung diseases.When gold nanoparticles are breathed into the alveoli,they will interact with lung surfactant(LS).LS is a monolayer composed of lipid and protein,which is the first barrier against foreign substances.Therefore,it is very important to understand the interaction between gold nanoparticles and LS monolayers.Although a large number of experimental studies have been carried out,molecular level mechanism of interaction is still poor understood.Therefore,the effects of ligand density,ligand length and core diameter of gold nanoparticles with different hydrophobicity on the monolayer composed of DPPC,POPG,cholesterol and SP-B polypeptide were studied by using the coarse-grained molecular dynamics method.The specific work is as follows:(1)According to the actual structure of LS monolayer,two different states of lipids monolayer models(with different initial surface tension)were constructed,and four different shapes of gold nanoparticles were constructed.The interaction between gold nanoparticles and lipids monolayer was studied.The influence of the shape of gold nanoparticles on the physiological properties of lipids monolayer was discussed by analyzing the order parameters and interaction energy of phospholipid molecules.(2)By changing the density,length and diameter of the two ligands,the interaction between gold nanoparticles with different hydrophilicity and phospholipid membrane and the process of gold nanoparticles penetrating through phospholipid membrane were studied,The effects of surface tension,ordered parameters,density distribution of lipids monolayer components and radial distribution function of lipids molecules on the structure and biophysical properties of lipids monolayer were revealed.The results showed that the hydrophilic gold nanoparticles were easier to penetrate through the monolayer,and the destruction of the lipids monolayer could be improved to some extent by increasing the ligand density and length.(3)By changing the concentration of the hydrophilic gold nanoparticles.We simulated the different concentrations of gold nanoparticles interact with lipids monolayer and process of penetration and analyzed the different concentrations of hydrophilic gold nanoparticles surface tension of the air water interface,the order parameter and density distribution of lipids molecules,lipids monolayer fluidity and clusters of nanoparticles in the influence of the formation.High concentrations of gold nanoparticles were found to disrupt normal biophysical activity in the lungs,leading to increased surface tension at the air water interface.