Files
Abstract
The history of bacteriophage (phage) use in the biomedical field is a checkered one. A century ago, phages were given to humans to fight an array of infections, but the introduction of antibiotic drugs such as penicillin and streptomycin slowed further phage development. The rise of antimicrobial resistance (AMR) in pathogenic bacteria has given phages a new start in clinical applications. Although naturally sourced and potent antibacterials, phages are specific to one target pathogen which raises questions about their applicability in clinical infections. Separately, a well-established broad-spectrum bactericidal molecule, nitric oxide (NO), has its own shortcomings. Nitric oxide is a potent free radical gaseous molecule produced naturally in the body to manage blood pressure, transfer messages in the nervous system, and target invading pathogens. However, due to the radical nature of this gas, and the reactivity of its donor molecules, its therapeutic lifespan can be quite short-lived. Consequently, each of these natural antibiotics has the potential to negate the downfalls of the other. This dissertation has the aim to investigate this potential through a series of projects outlining the individual and combined antibacterial efficacy of phages and NO. First, phages were successfully incorporated into a commercialized expanded polytetrafluorethylene (PTFE) material through a nanoemulsion (NE) makeup. Even encapsulated within a NE and further into a porous solid material, the phages maintained their antibacterial potency to develop a new class of antibacterial, cyto- and hemo-compatible biomaterial. Simultaneously, NO was incorporated into a thin latex to generate an antibiotic material to be used for sexual health, catheter development, or wound dressings. Each of these materials showed enhanced antibacterial effects against pathogens with antimicrobial resistant phenotypes while maintaining biocompatibility showing strong potential that when utilized together, powerful bactericidal effects would be possible. Finally, when tested in solution together, the combination of NO, in the form of S-nitrosoglutathione (GSNO), and bacteriophages showed synergistic killing against the targeted Escherichia coli and broad-spectrum killing against a non-target pathogen, methicillin-resistant Staphylococcus aureus. When incorporated into hydrophilic gel matrices, a delayed phage delivery was shown as the phage-incorporated alginate beads slowly broke down within the GSNO-loaded thermogel matrix. The reactive GSNO released NO for the initial several hours of use as the phages traveled through the gel to be released once the GSNO payload was almost depleted. Taken together, the incorporation of NO in combination with phages has increased the broad-spectrum killing capacity of phages while the phages have helped to lengthen the therapeutic lifespan of NO-based biomaterials providing key findings for further development of phage-NO combinatorial biomaterials.