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Date of Award
Doctor of Philosophy (PhD)
Jonathan L. Machta
In the past decade, polyelectrolyte complexes (PECs) have received considerable attention as novel therapeutic agents for gene delivery technologies. The process of the gene delivery contains the formation of PECs, and the releasing of DNA from the PEC in the presence of longer polyanions inside the cells. These two aspects were studied, yet not completely understood so far. We made our contributions in these two aspects by studying two important questions in two chapters.
In the first chapter, we studied the formation mechanism of single polyelectrolyte complex (PEC). The central question of chapter is the effective driving force between two polyelectrolytes during the complexation. This question was stated, studied and answered by Langevin dynamics simulation in both no salt and salty conditions. The conformation and degree of ionization change of chains were also systematically analyzed in this study. We found that a constant driving force between polyelectrolytes under certain circumstances in this process.
In the second chapter, we investigated the mechanism of the DNA releasing by studying the substitution reaction of single PEC. The central topic in this chapter is the substitution efficiency, i.e., how hard/easy the substitution would happen. We answer this general question by discussing the minimum length of invader needed for an efficient substitution. We have concluded that the impetus of substitution reaction is the entropy gain due to counterions replaced by monomers in the formation of new complex.
In the third chapter, motivated by the recent discovery of conductivity increase of PSS:PEDOT complex in ionic liquids(ILs), we investigated the effects of salt and ILs on PECs, and concluded that the stability of PEC is the result of the competition between the charge density of chains making the PEC and the concentration of salt around the PEC. Moreover, we studied the novel structure of PEC in the presence of ionic liquids (ILs), and suggested the direction of future theoretical study for this topic.
Peng, Bo, "Theory and Simulations of Polyelectrolyte Complexes" (2014). Doctoral Dissertations 1896 - February 2014. 563.