Date of Graduation

12-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemistry (PhD)

Degree Level

Graduate

Department

Chemistry & Biochemistry

Advisor/Mentor

Jingyi Chen

Committee Member

Yong Wang

Second Committee Member

Colin D. Heyes

Third Committee Member

Kyle Quinn

Fourth Committee Member

Roger Koeppe

Fifth Committee Member

Suresh Thallapuranam

Keywords

Antimicrobial application, Controlled release of FGFs, Injectable hydrogels, Silver nanoparticles, Silver/gold alloy nanostructures, Wound healing

Abstract

This work focuses on the synthesis of biocompatible polyethylene glycol (PEG)-based hydrogels, silver nanoparticles (AgNPs), and silver-gold nanocages (Ag-AuNCs) for biomedical applications. The dissertation includes two parts with Part I on the work of PEG-based hydrogel for wound healing applications and Part II on the work of Ag/Au nanostructures for antimicrobial applications. Part I studies PEG-based hydrogel for the delivery of fibroblast growth factors (FGFs) for wound healing applications, aiming to overcome the challenge of designing hydrogels capable of the sustained release of bioactive FGFs. This research develops new biocompatible anionic injectable hydrogel formulations based on Poly (Oligo Ethylene Glycol Monoacrylate-Acrylic Acid- N-Isopropylacrylamide) (POEGA-AA-NIPAM) using a simple and robust free-radical polymerization reaction. Chemical and physical properties of these hydrogels were characterized while feasibility for controlled release of FGFs from these hydrogels was examined in vitro. P(OEGA-AA-NIPAM) hydrogels were able to achieve sustained release of active human acidic FGF (hFGF1) which improved wound healing in vivo. This study promises a delivery system with tunable charge distribution for the delivery of active positively charged proteins for wound healing applications. Part II explores the effects of surface chemistry, morphology, and composition of Ag/Au nanostructures on their antimicrobial properties. It was found that the positively charged AgNPs caused a reorganization of histone-like nucleoid structuring (H-NS) protein of E. coli, resulting in enhanced antimicrobial activity while polydopamine (PDA) coating could synergize with AgNPs to increase antimicrobial killing against E. coli. The synergistic effect of PDA on antimicrobial activity of AgNPs that spectroscopic studies revealed to be from coordination of catechol group of PDA and Ag in the coating to generate reactive oxygen species (ROS). Further, Ag-AuNCs with different Ag/Aumolar ratios showed higher antimicrobial activity than pure AgNPs unveiling a synergistic effect between Au and AgNPs that depends on the Ag/Au composition and morphology of the alloy. This study provides insights on tailoring the antimicrobial properties of Ag/Au nanostructures through nanochemistry.

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