Date of Award

5-11-2025

Date Published

June 2025

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biomedical and Chemical Engineering

Advisor(s)

Mary Beth Monroe

Keywords

degradable biomaterials;gelatin;hemostatic dressing;polyurethanes;tissue engineering;traumatic wound healing

Abstract

Every year, 1.5 million people die from uncontrolled bleeding in traumatic wounds, such as gunshot wounds. Gauze dressings have remained the gold standard of treatment for traumatic wounds, but gauze must be removed, resulting in wound rebleeding. Furthermore, gauze removal within an approved time frame is not always possible in remote settings, like on a battlefield, presenting a critical need for a safe and effective dressing that can control bleeding over prolonged periods. To overcome these limitations, this work focuses on a novel biomaterial to be used as a permanent dressing to stop bleeding and facilitate healing. In previous work, polyurethane (PUr) foam dressings demonstrated effective bleeding control in a lethal pig liver injury model, with increased pig survival after PUr foam treatment compared to the clinical treatment options. Ideally, these PUr foams can safely remain in a wound and degrade, eliminating the need for removal. Their degradation rate should match wound healing rates to support new tissue formation. This work improves upon the traditionally slow degradation rate of PUr foams by incorporating linkages that are susceptible to breakdown by water and oxygen that are present in blood and tissue. Additionally, a biodegradable foam dressing can provide the framework for cells and tissue to migrate on, ultimately providing new, healthy tissue with no remains of the applied dressing after healing. Incorporating bioactive, naturally derived proteins like gelatin and collagen can drive these cell interactions on an otherwise entirely synthetic material. To that end, this work aimed to (i) increase PUr foam degradation rates to match the rate of traumatic wound healing (~12 weeks) and (ii) incorporate bioactive gelatin and collagen into the foams to further promote healing. A library of biodegradable polythiols was made from hydrolytically labile esters and oxidatively labile thioethers synthesized via a rapid click-chemistry reaction. Then, these polythiols were incorporated during foam fabrication to produce a library of PUr foams with varying amounts of the degradable groups. The degradable linkages significantly increased the rate of foam degradation, with almost complete degradation within 12 weeks, compared to the control PUr foam without these linkages, which had ~80% mass remaining at 12 weeks. Additionally, gelatin and collagen were physically or chemically incorporated into the foams, and their effect on blood- and cell-material interactions was assessed to determine their clotting and healing capacity. The incorporation of procoagulant gelatin and collagen significantly increased blood and protein interactions with the foams, helping to induce a stable clot to stop bleeding faster. Furthermore, gelatin and collagen increased cell attachment, spreading, and proliferation on the foams, which are important for new, healthy tissue formation. This work significantly improves upon previous work to increase the degradation rates of PUr foams. The degradable linkages are made via a simple, rapid, solvent-free reaction that can easily be scaled up for future commercialization to broaden access to a safe, effective wound dressing. Furthermore, the increased bioactivity of the PUr foams increases cell interactions on the scaffold, which can facilitate long-term healing. Ultimately, a comprehensive biodegradable and bioactive foam dressing can improve traumatic wound healing outcomes to reduce morbidity and mortality in millions of patients each year.

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Open Access

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Available for download on Thursday, June 18, 2026

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