Date of Award
Doctor of Philosophy (PhD)
The total population of diagnosed and undiagnosed diabetes mellitus in the United states is expected to rise by 54% between the years of 2015 and 2030 contributing to $200 billion in health care expense. The exponential rise in common diabetic wounds, such as diabetic foot ulcers, puts a large population at risk for complications such as infection, amputation, and even death. Peripheral neuropathy leading to late diagnoses, patient non-compliance, and lack of holistic treatment options all contribute to complications with the incidence of new ulcer formation after treatment reaching 50%. This work explores the design, development, and in vitro evaluation of a multicomponent textile-based biomaterial and absorptive dressing that combines the need to manage infection, eliminate excess exudate levels, and provide an ideal environment for healthy tissue to repair and remodel the wound site.
Melt-splun poly-l-lactide (PLLA) yarn of fibers with round or 4-deep-grooved (4DG) geometry were knitted into the skin-contact layer, the first layer of the dressing. Different methods of gentamicin sulfate (GS) incorporation, along with the impact of fiber geometry, were studied to explore optimal antibiotic release and efficacy. Results indicated that an increase in surface area as well as heat-enabled diffusion allowed for higher release of GS. Because each factorial treatment, with the exception of exhaustion dyeing method of incorporation, released GS at or above the minimum inhibitory concentration, there showed no difference in geometry and method of incorporation on antibacterial efficacy. The GS incorporated skin contact layer also appeared to be biocompatible in cultures of mouse bone marrow stromal D1 cells. Cell adhesion studies showed that a polyethylene glycol (PEG) surface treatment is needed to prevent non-specific protein and cellular attachment upon dressing changes. A microscopically thin layer of PEG was added to the surface of the contact layer and showed less cell attachment as seen in fluorescently labeled LIVE/DEADTM analysis, while showing no impact on GS release and antibacterial efficacy. In this aim, it can be concluded that the combination of GS release and a PEG surface coat can simultaneously kill and prevent infection while providing a non-adhesive surface upon removal from the wound.
Polyurethane (PU) foam was characterized in a two-factor analysis based on foam density and mixing speed used to create the foam layer. PU foam V was chosen as the absorptive layer of the dressing and a comparative analysis was conducted using commercialized absorptive dressings. The PU foam layer was exposed to different time durations of ultra-violet ozone to increase the surface wettability and initiate moisture absorption. To prevent saturation, PLLA yarn of 4DG fibers was braided into an evaporative and moisture wicking layer. The braided fabric was able to vertically wick porcine serum at a rate of 0.88 mm/sec. The combination of absorptive and moisture wicking layers stimulate wound healing by removing moisture from the ulcer, while preventing maceration and premature saturation of the dressing, leading to fewer dressing changes.
Additionally, an in vitro chronic wound model was constructed to verify the efficacy of the combined layers of the dressing. After applying the dressing for a duration of 48 hours, the dressing inhibited bacterial infection, while acting as a superabsorbent material without causing saturation. Further work explored healthy cell viability and any oxidative stress levels after exposing cells to both bacterial infection and the dressing. Although the in vitro model maintains some limitations and assumptions at the present time, it can be concluded that with the addition of the wound dressing, cell viability increased over time, and therefore promoted tissue repair. Future work will explore alternative antimicrobials for a more gradual release as well as improving the in vitro model by discovering the interaction between the co-culture in different types of medias and substrates while including proinflammatory biomarkers that could affect oxidative stress.
Gianino, Elizabeth, "Influencing the Inflammatory Response Through Multi-Scale Geometry, Antibiotic Release, and Fluid Management in a Textile-Based Biomaterial Wound Dressing" (2021). All Dissertations. 2924.