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Sarah J. Moore
Maren E. Buck
Bachelor of Science
Cancer, Targeted cancer therapy, Fibronectin, Protein engineering, Polymer, Azlactone, Protein-polymer conjugation, Integrin, Drug targeting, Polymerization
Conjugation of proteins to well-defined polymers is a promising strategy for developing effective target-specific cancer treatments. Protein-polymer conjugates (PPCs) overcome many limitations of protein therapies and polymer-based therapeutics, providing long circulation half-life, storage stability, and controlled ligand binding to target-specific biomarkers. The goal of this thesis was to develop a novel site-specific protein-polymer conjugation system to address the unmet needs of current cancer therapies. Two different conjugation strategies, primary amine and thiol-ene conjugation, were studied.
For primary amine conjugation, poly(2-vinyl-4,4-dimethylazlactone) (PVDMA), synthesized via reversible addition-fragmentation chain transfer polymerization, was functionalized with triethylene glycol monomethyl ether (mTEG) to improve solubility in aqueous solution. This polymer was conjugated to Fn3 RDG, a non-antibody protein representative of fibronectin type III (Fn3) scaffold libraries. Protein gel analysis verified the successful conjugation of proteins to the polymer via primary amine chemistry.
For thiol-ene conjugation, PVDMA was modified with substoichiometric equivalents of mTEG and 1-buten-1-ol. mTEG improves the solubility and the alkene on butenol allows the thiol-ene conjugation with the engineered protein RGD-cys; the RDG amino acid sequence in Fn3 protein was mutated to RGD and a cysteine tag contains a thiol group was inserted. The RGD sequence can recognize the integrin receptor which is overexpressed on many cancer cells. The RGD sequence allows the PPC to target integrin-expressed cancer cells. In this thesis, glutathione was used as a protein model and successfully conjugated to the polymer. Data from ultraviolet-visible spectroscopy confirmed successful conjugation. For the next step, the engineered protein will be conjugated to the polymer using the developed thiol-ene reaction. In future work, PPCs will be tested with tumor cells expressing integrin receptors to characterize the potential of these conjugates to deliver therapeutic molecules to sites of disease.
©2020 Yanxuan Li. Access limited to the Smith College community and other researchers while on campus. Smith College community members also may access from off-campus using a Smith College log-in. Other off-campus researchers may request a copy through Interlibrary Loan for personal use.
Li, Yanxuan, "Site-specific protein-polymer conjugation for targeted cancer therapy" (2020). Honors Project, Smith College, Northampton, MA.
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