Galactose-Decorated Polymers and Nanogels Synthesized via Reversible Addition-Fragmentation Chain Transfer Polymerization for in vitro Tumor Targeted Drug Delivery and Gene Knockdown

• Author / Creator

  Quan, Stephen

• The first part of this thesis focuses on the synthesis and development of thermosensitive galactose-based nanogels, evaluating their potential in encapsulating and releasing Iodoazomycin Arabinofuranoside (IAZA), a clinical drug for imaging solid hypoxic tumors, for its hypoxia-selective theranostic (therapy + diagnostic) potential in the management of hepatocellular carcinoma. The shell of the nanogels is decorated with galactose molecules to facilitate asialoglycoprotein receptor (ASGPR)-mediated uptake in HepG2 cells. The nanogels were synthesized via reversible-addition fragmentation chain transfer (RAFT) polymerization having a temperature responsive core and permanently hydrophilic shell. The molecular size of the nanogel, cross-linker concentration and the presence of cationic/anionic moieties impacted the encapsulation efficiency of IAZA. The release profile of IAZA from the nanogels’ core demonstrated a stable, non-burst release of IAZA over time with excellent biocompatibility. The radiosensitization studies with nanogel-IAZA demonstrated that IAZA in encapsulated form offers superior radiosensitization capacity of hypoxic cells as compared to the parent IAZA drug. The second part of the thesis describes the synthesis of a series of statistical and block glycopolymers composed of 2-lactobionamidoethyl methacrylamide (LAEMA) and cationic monomer 2-aminoethylmethacrylamide hydrochloride (AEMA) for the delivery of epidermal growth factor receptor (EGFR)-small interfering RNA (siRNA) knockdown in HeLa cells. The colloidal stability of the glycopolymer-siRNA complexes was assessed by dynamic light scattering (DLS) and gel electrophoresis in the presence and absence of serum proteins. Their cytotoxicity, cellular uptake and transfection efficiencies were examined in HeLa cells. The shortest AEMA diblock glycopolymer was the most effective in EGFR gene silencing, however it exhibited a higher toxicity profile in comparison to its statistical counterpart at higher weight/weight ratios. Regardless of the presence or absence of serum proteins, the glycopolymer-siRNA polyplexes demonstrated excellent knockdown efficacies. Preliminary in vitro studies indicate that delivering IAZA drug in encapsulated form enhanced the radiosensitization of hypoxic hepatocellular cancer cells. Additional studies with EGFR gene knockdown in HeLa cells was achieved using EGFR siRNA complexed with galactose-based diblock glycopolymers synthesized via RAFT polymerization. In future studies, galactose-decorated nanogels will be used to assess the delivery and radiotherapeutic potential of radioiodinated IAZA to hypoxic HepG2 cells, along with in vivo biological evaluation of galactose-based nanogels in physiological organs for their capacity in targeting liver carcinoma and delivering IAZA for radiotherapeutic treatments. Future studies with cationic galactose-based polymers will be pursed and evaluated in vivo to demonstrate their potential as polymeric macromolecule carriers for increased sensitivity, biocompatibility and targeting in gene knockdown using mammalian models. Furthermore, additional studies to evaluate the efficacy and capacity of galactose-based nanogel to deliver other nitroimidazole-derived radiosensitization agents and small molecule drug compounds will also be useful. Finally, other monosaccharide carbohydrate-based polymer systems, such as glucose and mannose, should be evaluated for their in vivo and in vitro applications in drug delivery and gene knockdown.

• Subjects / Keywords

  • IAZA
  • Nanogel
  • ASGPR

• Graduation date

  Spring 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R39C6SB6M

• 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.