Publication Date

2020

First Advisor

Sarah J. Moore

Second Advisor

Maren E. Buck

Document Type

Honors Project

Degree Name

Bachelor of Science

Department

Engineering

Keywords

Cancer, Targeted cancer therapy, Fibronectin, Protein engineering, Polymer, Azlactone, Protein-polymer conjugation, Integrin, Drug targeting, Polymerization

Abstract

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.

Rights

©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.

Language

English

Comments

70 pages : illustrations (some color) Includes bibliographical references (pages 61-69)

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