Combinatorial approaches for the synthesis of protein-polymer conjugates (PPC) for drug delivery

Ama Boamah


Cancer is a global disease that leaves its victims and families in emotional and psychological distress. The impact it has on the global scale is significant, both in terms of human health and economic cost. Traditional cancer therapies like surgery, chemotherapy, and radiation therapy can have significant side effects, which underscores the need for more precise and targeted approaches. Targeted delivery of therapeutic molecules to cancer cells using engineered proteins and polymers has the potential to improve the delivery of cancer therapeutics and reduce side effects. Protein-polymer conjugates (PPCs) are a current drug delivery technology that have been used in drug delivery and nanoparticle applications. The use of specific protein ligands is for targeted cancer treatments to improve binding specificity between drug carriers and receptors overexpressed in cancer tissues. Thus, my overall goal is to synthesize side-chain functionalized reactive polymers and conjugate these polymers to various proteins to understand optimal conditions for conjugation as we aim to develop improved targeted cancer therapies. In my thesis project, a reactive ester polymer [poly (pentafluorophenyl acrylate) (PPFPA)] was synthesized via reversible addition-fragmentation chain-transfer polymerization (RAFT) and functionalized with stochiometric equivalences of a hydrophilic side-chain group [2-(2-(2-Methoxyethoxy)ethoxy)ethanamine (mTEG-amine)] to make the polymer soluble in aqueous solution. These side-chain functionalized reactive polymers were then conjugated to primary amine residues (N-terminus and lysines) on holo-transferrin and fibronection III proteins. SDS-PAGE analysis was used to assess the conjugation efficiency, and data showed conjugation 5 was successful. This process of conjugation was optimized to improve conjugation efficiency using various stoichiometries of side-chain reactive functionalized polymers, different proteins, and different polymer and protein concentrations. Future works will focus on isolating the conjugates using size exclusion chromatography and assessing the binding affinity of the PPCs on tumor cells expressing avβ3 integrin and transferrin receptors.