چكيده به لاتين
One of the most important challenges in the process of DNA sequencing using nanopores is controlling the translocation velocity of DNA. To overcome this challenge, many methods are used, among them one can mention covering the inner walls of the nanopore with a layer of polyelectrolyte (PEL), i.e. the use of soft nanopores. In this study, the translocation of DNA through pH-regulated nanopores has been theoretically investigated. The polyelectrolytes is considered to be made up of either acidic (acid citric) or basic (imidazole) functional groups. For the acidic PEL the electroosmotic flow caused by polyelectrolytes charge was found to be in the opposite direction of DNA electrophoresis, and to reduce the speed of DNA translocation up tp 0.4 m/s in maximum. However, in the basic case, electroosmotic flow and electrophoresis were found to be in the same direction, and the presence of a PEL was found to lead to an increase in DNA translocation velocity. It seemed that by adjusting the pH value and using polyelectrolytes that contain acidic functional groups, the DNA translocation velocity can be changed and set at a desired value. It was found that in range of 5 to 6.3 pH values for both cases where the PEL contains acidic or basic functional groups, an increase in pH leads to a decrease in DNA translocation velocity. But in the acidic case, further increase in pH (between 6.3 to 6.8), changes the direction of DNA translocation. Ultimately, conducting the process in a particular range of pH values (close to range of 6.3 to 6.8), and at higher pH values, in the cases of using PELs of acidic nature, and basic nature, respectively, was recommended. The ion partitioning effect has also been investigated, and the results show that the ion partitioning effect leads to an increase in electroosmotic flow, and for acidic and basic cases, decrease and increase the DNA translocation velocity in the direction of electrophoresis up to 0.04 m/s, respectively.
