Date of Award
2024
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Biomedical Engineering
First Advisor
Amber Doiron
Abstract
The eye is made up of various components that work together to form a person’s vision. Among them is the cornea, which plays a key role in protection and focusing. Keratitis is an infection of the cornea that can be caused by a variety of pathogens, with the focus of this research being on the most frequent cause of bacterial keratitis, the gram-negative bacterium Pseudomonas aeruginosa. Current treatment involves the use of topical antibiotics with highly frequent reapplication. With improper treatment or poor patient compliance, the corneal infection can rapidly progress, leading to vision impairment or vision loss. With the growing concern of antibiotic resistance, adaptation of treatment standards is occurring and highlights the need for alternative therapeutic strategies. This research explores the potential of a targeted photodynamic therapeutic (PDT) approach to treating bacterial keratitis using pulsed plasmonic laser photoablation. To induce the photoablative effect of the applied femtosecond NIR laser, gold nanoparticles are used for their unique optical properties that allow for the ejection of electrons from the electron cloud of the nanoparticles after excitation. The ejected electrons then interact with the surrounding environment to produce short-lived reactive oxygen species that disrupt the cellular membrane of the bacteria. At low power densities, the laser induces death only in the bacterial cells to which the particles are attached without affecting the temperature of the surroundings or harming native tissue. The gold nanoparticles are conjugated with antibodies to P. aeruginosa for specific targeting of the bacteria, and the particles are coated with a hydrophilic polymer to reduce nonspecific protein adsorption or binding. Characterization methods including measuring the peak absorbance wavelength shift following conjugation as well as examining the hydrodynamic size, zeta potential, and polydispersity index of the nanoparticles showed successful antibody conjugation, nanoparticle stability, and uniformity. Attachment of the nanoparticles to the cell wall of the bacteria was examined using spectrophotometry and imaging techniques, including darkfield microscopy and transmission electron microscopy (TEM). TEM images visually suggested successful attachment, although limitations of sample preparation for both microscopy techniques make further examination needed for a definitive conclusion. Irradiation of bacteria treated with immunogold bioconjugate nanoparticles showed a large decrease in cell viability compared to the untreated bacteria. These results show that a targeted pulsed plasmonic laser photoablation-based therapy using gold nanoparticles has potential for success as a non-thermal approach to treating bacterial keratitis.
Language
en
Number of Pages
92 p.
Recommended Citation
Jacobson, Kelly Jean, "Photoablation-based Treatment for Bacterial Keratitis Using Immunogold Bioconjugate Nanoparticles" (2024). Graduate College Dissertations and Theses. 1963.
https://scholarworks.uvm.edu/graddis/1963
Included in
Biomedical Engineering and Bioengineering Commons, Nanotechnology Commons, Optics Commons