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theses

Biodegradable, bioactive-based polymers have been successfully employed as sustained bioactive delivery systems. This dissertation describes bioactives that have been chemically incorporated into novel, biodegradable polymers via covalent bonds for controlled, sustained, and tunable release properties. Bioactives are released from polymers via hydrolytic degradation. The polymers described herein utilize alternative synthetic methods and a wide array of bioactives, including antibiotics, antioxidants, antimicrobials, and anti-inflammatory drugs. One goal is to focus on naturally-occurring bioactives that are generally regarded as safe (GRAS) by the FDA. First, poly(anhydride-amides) comprised of ampicillin were synthesized and formulated as coatings. Polymer adhesion onto medical-grade stainless steel surfaces was assessed and in vitro release characterized. Cytocompatibility and antibacterial activity elucidated polymer safety and efficacy for potential in vivo use. These localized delivery systems could mediate the issues caused by implant surgery. Second, poly(anhydride-esters) comprised solely of naturally-occurring phenols and EDTA were synthesized and physicochemical properties determined. Bioactive release was ascertained, in addition to antioxidant activity and activity against Gram-positive and Gram-negative bacteria. These polymers can act as potential preservatives, increasing cosmetic and food product shelf life through antioxidant and antimicrobial pathways. Third, through environmentally sustainable (i.e, green) methods, polyesters with pendant anti-inflammatory groups and a sugar-based backbone were prepared with minimal solvent use, enzymatic catalysis, and biorenewable reactants and reagents. Three comonomers of varying hydrophobicity were tested to elucidate changes in polymer thermal properties and bioactive release rate. Fourth, poly(anhydride-esters) with a mannitol backbone and multiple bioactive groups per repeat unit were developed as the first linear, biodegradable polymers with high bioactive loading (~70%) using a polyol. In vitro ibuprofen release was quantified and an anti-inflammatory assay determined that bioactive retained activity upon polymer degradation. Alteration of polyol, bioactive class, and other facets leads to highly tunable polymer properties. Last, to combat bacterial spoilage and oxidation, poly(anhydride-esters) containing natural antimicrobials were designed for food applications. Bioactive released from polymer exhibited radical scavenging ability and antibacterial activity. Furthermore, polymers were blended with current food packaging materials (e.g., polyethylene) and molded into films for active food packaging that contains a higher percentage of biodegradable content.

ETD_6558

Ph.D.

Includes bibliographical references

by Nicholas David Stebbins

doi:10.7282/T3NZ89NX

ETD doctoral

The author owns the copyright to this work.