Theory Model Of Biomacromolecule Through The Nanopore Including The Effect Of Electrolyte And Excluded Volume

The translocation process of biomacromolecule through nanopores is a common and significant biological phenomenon that widely exists in biology, medicine, pharmacology. The examples include transportation of viral genome, translocation of ribonucleic acid (RNA)through nuclear pore complexes, translocation of protein through the mitochondria and drug molecules transportation across the cell membrane.With the assumption that charged ions in the electrolyte solution are discrete particles, a theoretical model of translocation process of DNA molecules is established. The model is based on the Poisson equation, Fokker-Planck equation and Navier-Stocks equation. In the model, DNA molecule is driven by electroosmotic flow through nanopores that are filled with electrolyte solution. The biomacromolecule is regarded as a self-avoiding polymer chain and actuated by external potential, a theoretical model of translocation process of biomacromolecule is developed by the self-consistent field theory. Several effects have been included in the theoretical model, such as external potential, Coulomb electrostatic potential of charged ions (electrolyte effect), the attractive interaction between polymer and nanopore (the excluded volume effect). It is important to study the effect on free energy landscape and conformation entropy at each translocation stage. The results show that, the entropy barrier of polymer in the solution with higher valence electrolyte is much larger than in the one with lower valence electrolyte under the same condition, as a result,the translocation time of the DNA molecules in the solution with higher valence electrolyte is increasing. In addition, the attractive interaction between polymer and nanopore increases free energy of polymer, leading to the probability of success through the nanopore is increased. The average translocation time decreases with an increase of excluded volume effect parameter ω. And electrolyte effect can prolong the average translocation time.