The interaction of nanoparticles with cell membrane is critical in many applications of nanoparticles such as phototherapy,imaging,and drug/gene delivery.These applications require a well understand the mechanism for the nanoparticle-membrane interactions.In this talk we will summarize our recent dissipative particle dynamics studies on the mechanism of nanoparticle uptake into a cell.We find that physical and chemical properties of nanoparticles,such as nanoparticle shape,stiffness,and especially surface coating,have significant influences on their interaction with cells.We first illustrate the dependence of detailed kinetics for the endocytosis of ligand-coated nanoparticles on nanoparticle shape.Our results indicate that the rotation of shaped nanoparticles,which is one of the most important mechanisms for endocytosis of anisotropic nanoparticles,regulates the competition between ligand-receptor binding and membrance deformation.Besides,we find that rigid nanoparticles can be internalized in a more efficient manner than chain-and micelle-like(soft)nanoparticles.Next,we discuss the internalization of stripy spherical nanoparticles coated with alternating hydrophilic and hydrophobic ligands.We found some stripy nanoparticles are found to penetrate spontaneously the cell membrane without overt bilayer disruption,while others may induce the membrane rupture,depending on ligand arrangement.In addition,we also show the effects of surface charge distribution on the self-assembly of patterned nanoparticles and the endocytosis dynamics.Finally,we also discuss the endocytosis of multiple nanoparticles having like charges,from which a highly counterintuitive phenomenon is observed: multiple like-charge NPs are internalized with a cooperative pathway.