Research Of Endocytosis Of Bio-particle As A Microcanonical Ensemble

Most Viruses invade living cells through receptor mediated endocytosis,in which the ligand on the outer surface of viruses bind specifically to the membrane receptors.Specific ligand-receptor binding of great importance for endocytosis.It is experimentally demonstrated that the endocytosis rate is related to the size and shape of viruses.It is found that the dimension of ligand-receptor complexes and the depletion effect due to the small bio-particles within the cellular environment could affect the interaction between virus particles and cell membrane.Although the relative experiments have revealed the geometrical effect of virus on endocytosis and shed light on the design of nanoparticles(NPs)for drug delivery and targeted therapy,the underlying mechanism of the effect of relevant parameters on receptor mediated endocytosis is still not thoroughly understood.In recent years,several theoretical models based on thermodynamics have been proposed to pursue the underlying mechanism on the receptor-mediated endocytosis,but few models considered the influences of the depletion interaction as well as the dimension of receptor-ligand complex.Based on the previous work,we present an extended analytical model including the depletion effect and the dimension of ligand-receptor complex,aiming to elucidate their influences on endocytosis of spherocylindrical NPs.The endocytosis phase diagram constructed in the plane of NP radius and relative aspect ratio indicates that the endocytosis of NP is enhanced evidently by reducing the optimal radius and the threshold radius of endocytosed NP.Meanwhile,through thermodynamic and kinetic analysis of the diffusion of receptors,the dependence of diffusion length on depletion effect and the dimension of ligand-receptor complex can be identified in great detail.For small aspect ratio,diffusion length decreases with increasing concentration of small bioparticles incellular environment.The values of endocytosis speed corresponding to large radius and high concentration of small particles strongly depend on the increasing(2r-?).These results may show some highlights into the conscious design of NPs for diagnostic agents and therapeutic drug delivery applications.