Dynamics Of Polymer Translocation Throuhg Kinked Nanopores And Multivalent Polymer Adsorption On The Surface

The phenomenon of polymer confined can be easily found in the application of materials and in biology.Polymer can be confined in1D,2D and3D space.In recent years,the dynamics and conformation of confined polymer have attracted considerable and deep attentions.On the one hand,it can help us comprehend many phenomena in biology deeply.On the other hand,it has bright pospect on some advanced techmological fields.For example,the translocation of polymer through nanopore has key effect to the next generation of gene sequecing.In the thesis,the dynamics of polymer translocation through kinked nanopore and the dynamics and confomation of multivalent polymer adsorpion are examined by us using computer simulation.One of the key problems in the next generation of gene sequencing is how to slow down the translocation rate of DNA through the nanopore,so that the bases of the DNA can be sequenced one by one as it pass though the nanopore.In chapter3, using Langevin dynamics simulations, we investigate the dynamics of polymer translocation through kinked nanopores in two dimensions under an applied external field. Com-pared with a cylindrical pore, the dynamics of translocation through kinked nanopores is pronouncedly different due to the stronger polymer-pore interaction. We construct five kinds of zigzag nanopores based on varied tortuousness in order to plot the θ de-pendence of the translocation time and the success ratio. In comparison with straight pore,the translocation time of kinked pore increases remarkably as the increasement of θ.This result is in consistent with one previous experimental work.In chapter4,we explored the binding efficiency of polymer carrying multisites with cell surfaces displaying tunable receptor density.In the early year of1988,Prof. Mammen et al.found that the interaction of multiple ligand-receptor exists widely in biological system and they put forward the theory of multivalency.This theory argues that,the association of different biological molecules or surfaces is the consequence of the multiple interaction of ligand-receptor.Though,various multivalent polymers have been synthesized and their adsorption behavior have been explored by experiments,the detailed understanding of multivalency is still lacked.Prof. Frenkel et al.found multiva-lentpolymer or multivalent nanoparticle has superselectivy to the surface with multiple ligands.Our results is in consistence with theirs.Besides, we find an interesting and novel phenomenon that the radius of gyrations of the chain has a maximum with increasing of the receptor density. In addition, the peak value occurs at lower surface density when Φ increases to0.34. The scaling exponent of the radius of gyration parallel to the sur-face decreases with the increasement of surface receptor density. The adsorption time decreases as the increasement of φ.But this decreasement doesn’t last too long until φ increase to a certain value.