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Translocation of Star Shaped Polyelectrolyte Through Nanopore

Aghajani, Zeinab | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49861 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Ejtehadi, Mohammad Reza
  7. Abstract:
  8. Polymer translocation through the nanopores is one of the fundamental macromolecular processes in life. Some examples are , mRNA translocation through nuclear pores, injection of DNA from a virus head into a host cell, protein translocation across biological membranes through membrane channels. Also some applications are suggested for the process, e.g. DNA sequencing by probing the signals during the translocation, drug delivery and/or gene therapy. During the translocation the polymer should pass entropic barrier of the pore and it can be facilitated by changing the chemical potential, application of eclectic field, flow field, or chemical concentrations. In electrically driven translocation, the process can be devided to three steps. First of all, the polymer just by simple diffusion should approach a distance to the pore, called capture radius, where electric drift dominate diffusion fluctuations. Then, inside the capture radius, it moves towards the pore entrance by electrical field. Then as soon as the polymer is caught at the pore mouth the translocation starts. It is clear that the structure of the polymer highly influences the translocation process and it is under question. In this project we intend to investigate translocation of the star shaped polyelectrolyte through the nanopore in presence of non-uniform electric field. We show that the translocation through the nanopore depends to the arms length. Also the dependence of the probability of finding the pore on the arms length is investigated. In the simulations, independent of arms length, only one configuration with just one leading arm is passing through the pore and the others follow it. However, the chance that the leader is the longer arm is always higher. To study the effect of electric field on dynamics of star shaped polyelectrolyte, we compute the extention and angle between the extension axis of the star and radial direction. We find as the distance to the pore reduces, the polymer become more elongated in direction towards to the pore. Moreover, the distribution of counter ion around the polymer is investigated. It shows that the counter ion density is higher in the center of the star and is decreasing by distance
  9. Keywords:
  10. Nanopore ; Translocation Phenomena ; Polyelectrolyte ; Macromolecule ; Star Shaped Polyelectrolyte

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