Year of Award

2017

Document Type

Dissertation - Campus Access Only

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Individualized Interdisciplinary Doctoral Program

Other Degree Name/Area of Focus

Biomedical Engineering

Department or School/College

Interdisciplinary Studies Program

Committee Co-chair

Michael F. Minnick, Jack L. Skinner

Commitee Members

Marisa L. Pedulla, M. Katie Hailer, William Gleason

Abstract

There is an impending need for alternatives to traditional antibiotics as bacterial strains become increasingly resistant. In the United States alone, the CDC estimates approximately 2 million people are affected by antibiotic resistant bacteria per year, resulting in 23,000 deaths. As an alternative to traditional antibiotics, viruses that specifically target and kill bacteria have been used to treat human bacterial infection. In this work, a treatment delivery system was created for iron-doped apatite nanoparticles (IDANPs) which significantly enhance bacterial killing by these viruses (bacteriophage or phage). This effect has been demonstrated across gram-positive and gram-negative bacterial species as well as with the use of phage of various tail morphology and genetic material. IDANPs must be prepared under specific conditions (25-45 °C, with 30 % iron-doping, and 5.5 mM citrate) in order to cause these significant increases in bacterial death. The synthesis parameters used during IDANP synthesis have also been shown to effect IDANP morphology, and subsequently, the extent to which these nanoparticles (NPs) interact with the bacterial surface. The effect of increased phage infection has not been replicated with other NP types or IDANP reagents alone. In in vitro investigations bacterial lawns grown from cells that were pre-exposed to IDANPs showed as high as double the amount of antibacterial activity of phage as compared to controls, and on average, an increase in phage infectivity of 80 % was observed. The IDANPs used in this research are composed of hydroxyapatite, which is found in in mammalian bones and teeth. The biomimetic properties of this material have led to substituted hydroxyapatites being used for a variety of biomedical applications including drug and gene delivery, as well as coatings for artificial bone materials and even as anticancer agents. The biocompatible nature of apatite coupled with the ability of phage to serve as a therapeutic alternative to traditional antibiotics make the enhancement of bacterial killing by phage of interest for medical applications and provide the motivation for this work. The following dissertation includes characterization of the IDANP, evaluation of IDANP effectiveness as adjuvants to phage infectivity, cytotoxicity evaluation of IDANPs in a mammalian system, and fabrication of a polymer treatment delivery system for IDANPs to enhance phage usefulness as antibacterial agents. This research has demonstrated that IDANPs are relatively amorphous particles exhibiting minimal cytotoxicity and significant enhancement of phage antibacterial activity and that IDANP-assisted phage therapy treatment delivered through an electrospun fiber mesh is an effective antibacterial treatment delivery method.

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© Copyright 2017 Jessica Marie Gregory