Carbohydrate and Phosphorylcholine based Polymers Prepared by Reversible Addition-Fragmentation Chain Transfer Polymerization for Gene Therapy

• Author / Creator

  Ahmed, M

• The study provides a comprehensive account on the development of novel synthetic carbohydrate and phosphorylcholine polymer based gene delivery vectors. Since the development and use of first non-viral vector for gene delivery applications, a wide range of polymers have been synthesized and studied for their gene delivery efficacies. With the advent of living radical polymerization, well-defined polymers with varying molecular weights, compositions and architectures have been synthesized and evaluated as potent gene delivery vectors. Reversible addition-fragmentation chain transfer polymerization (RAFT) has allowed the facile synthesis of tailor-made cationic polymers which are promising non-viral gene delivery vectors. Advanced structure-activity relationship studies between the polymers and gene expression have been possible due to the remarkable control in the design of these polymers via the RAFT process. In the first study, RAFT polymerization technique allows the successful synthesis of cationic glycopolymers containing pendant sugar moieties. A library of cationic glycopolymers of pre-determined molar masses and narrow polydispersities ranging from 3-30 kDa has been synthesized. These polymers differ from each other in their architectures (block versus random), molecular weights, and monomer ratios (carbohydrate to cationic segment). It is shown that the above-mentioned parameters can largely affect the toxicity, DNA condensation ability and gene delivery efficacy of these polymers. The effect of serum proteins on statistical and diblock copolymer based polyplexes and hence gene delivery efficacy is further studied. In the second study, 2-methacryloxyethyl phosphorylcholine (MPC) copolymers are studied for their ability to produce non-toxic and biocompatible materials. The cationic MPC copolymers of varying architectures (block versus random) are produced by RAFT polymerization technique. The copolymers produced are further evaluated for their, morphology, cellular uptake and gene delivery efficacy in the presence and absence of serum. The polymers with branched architecture are reported to be superior gene delivery vectors as compared to their linear analogues. In another study, hyperbranched glycopolymers of varying molecular weights and compositions are synthesized via reversible addition fragmentation chain transfer (RAFT) process and are further explored for their gene expression in vitro. Galactose based hyperbranched polymers are compared to glucose-derived hyperbranched polymers for their cellular uptake, toxicity, lectin interactions and gene expression. Furthermore, the cellular uptake and gene expression are studied in two different cell lines in the presence of lectins. The superior gene expression of linear statistical polymers is also accompanied by their significant aggregation in serum containing media. To solve this problem, carbohydrate and phosphorylcholine based cationic polymers having a novel architecture, different compositions and varying molecular weights are produced and are termed as cationic ‘block-statistical’ copolymers. These cationic copolymers are evaluated for their gene delivery efficacies, interactions with serum protein, cellular uptake and nuclear localization ability. In addition, MPC based ‘block-statistical’ copolymers and their sugar incorporated analogues are prepared and are compared with their statistical analogues for serum interactions and gene expression.

• Subjects / Keywords

  • Gene delivery
  • RAFT polymerization
  • Cationic Glycopolymers

• Graduation date

  Fall 2012

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3RD4B

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.