The effect of nanoparticle size on endocytosis dynamics depends on membrane-nanoparticle interaction

Molecular simulation studies on the interaction between nanoparticles (NPs) and cell membranes have been limited by small NP size of several nanometres. In this work, by using a simplified lipid model, we study the endocytosis of large NPs with a size being enlarged to 37.5nm. It is found that the effect of NP size on endocytosis dynamics depends on the membrane-NP interaction. As the interaction strength between NP and lipid changes, different wrapping modes are observed. For the system with weak membrane-NP attraction, the wrapping process is controlled by the membrane bending, and thus large size of NPs (within the range of NP size we studied) would promote the wrapping dynamics. While for the case with strong membrane-NP adhesion, the wrapping process is dominated by lipid diffusion and small NPs show a larger wrapping rate. In this wrapping mode, the membrane-NP adhesion drives small NPs to move towards the membrane as the wrapping process proceeds. For relatively larger NPs, however, the membrane moves towards the NPs instead. We also find that for the second wrapping mode, the rapid wrapping rate, especially with the hydrophobic ligands on the hydrophilic NP would impose significant perturbations on membrane stability, and consequently, membrane pores may be induced during the process of NP endocytosis.