Size and shape effects on receptor-mediated endocytosis of nanoparticles

We present a thermodynamic approach to elucidate the effects of the size and shape of nanoparticles (NPs) on endocytosis. It is found that endocytosis needs to surmount a thermodynamic energy barrier and has a minimum radius of NPs for endocytosis. Through referring to the concept of "diffusion length of receptors," we obtain a simple and analytical expression for the optimal size of NPs. Furthermore, a phase diagram has been constructed, which can clarify the interrelated effects of the radius and the aspect ratio of NPs. We can identify from the phase the relation between the geometry of NP and its endocytosis rate. The theoretical results are in good agreement with the experimental observations and reveal physical mechanisms involved in the effects of the size and shape of NPs on endocytosis, which implies that these studies may provide useful guidance to the conscious design of NPs for diagnostic agents and drug delivery applications. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3676448]