Receptor-mediated endocytosis of nanoparticle based on the co-rotational grid method

Abstract Endocytosis is a cellular process in which the nanoparticle can be internalized to form a vesicle. Receptor-mediated transport is a mainly endocytic pathway, and many theoretical models have been proposed to study the physiochemical mechanism underlying this specific endocytic pathway. Traditional methods mainly focus on the interactions between the nanoparticles and the plasma membrane. The role that actin force plays during endocytosis of nanoparticle is neglected. However, recent extraordinary studies show that the actin force is the main driving force in endocytosis. Based on previous instructive models and configurations of the actin network observed in literature, there mainly exist oblique push and pull forces generated by the growth of actin network at the endocytic site and the lateral contraction force produced by proteins such as myosin at the concave neck of membrane. Considering these two different actin force-generation mechanisms, a new actin force model is proposed in this paper. Then, a numerical analysis is performed based on the co-rotational grid method. Besides, and the influence of osmotic pressure, the plasma membrane stiffness, actin force containing growth process and asymmetry of the actin network have been investigated. Meanwhile, the relative importance of the two actin force-generation mechanism is obtained, which is consistent with the theoretical and experimental results in literature. Our model can obtain the critical nanoparticle radius that can be absorbed most efficiently by considering the force that actin filaments could provide. And our results show that there exist a critical size for nanoparticle which could only be absorbed by tumor cell. In addition, the effects of growth process and asymmetry of the actin network are discussed. This method has the potential to reveal the underlying mechanisms of the complex dynamic behaviors of the endocytosis process.