Preparation of Precise Bioconjugates Using Atom Transfer Radical Polymerization

This thesis shows the development of atom transfer radical polymerization (ATRP) for the preparation of biohybrid materials. The general flow of the thesis is an introduction to the field of bioconjugates (Chapter 1), then research that involved growing polymers from biomolecule initiators is covered (Chapter 2-4), followed by projects that conjugated preformed polymers to biomolecules. (Chapters 5 and 6). Chapter 7 covers unique class of biohybrids called polyplexes that are formed by electrostatic interaction between the polymer and biomolecules. Chapter 1 is a broad overview of the field of polymer bioconjugates (i.e. biohybrids) that are prepared using reversible deactivator radical polymerization methods (RDRP) and the
biomolecules covered are proteins, DNA and RNA. Chapter 2 describes the preparation of protein polymer hybrids by “grafting from” a genetically encoded non-canonical amino acid ATRP initiator expressed at the 134 amino acid residue in the green fluorescent protein using normal ATRP (Chapter 2A) and activators generated by electron transfer (AGET) ATRP (Chapter 2B). The development of ATRP under biologically relevant conditions (BRC) for the synthesis of welldefined protein polymer hybrids by “by grafting from” a protein initiator using both normal and AGET ATRP was explored in Chapter 3. DNA is a versatile biomolecules that is synthetically prepared using solid phase synthesis using phosphoramidite coupling chemistry. To incorporate
an ATRP initiator into DNA a phosphoramidite ATRP initiator was synthesized and incorporated into DNA and polymers could be “blocked from” DNA both on and of the solid phase bead (Chapter 4). The preparation of reversible DNA mediated star-polymer assemblies is described in Chapter 5. A self-transfecting nuclease resistant siRNA delivery system was developed by coupling a polymer to both the 5’ and 3’ ends of a passenger RNA strand followed by guide strand aneling (Chapter 6). A cationic nanogel was prepared, using AGET ATRP in inverse miniemulsion, and used to form polyplexes with siRNA. The nanogels were capable of binding and delivering siRNA to knockdown a protein of interest (Chapter 7).