Browsing by Author "Heyne, Belinda JM"

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    Singlet Oxygen Production and Its Kinetics in Nanoparticle-Photosensitizer Hybrid Systems
    (2021-09-24) Kabanov, Vladimir; Heyne, Belinda JM; Heyne, Belinda JM; Trudel, Simon; Anikovskiy, Max; Fraser, Marie E; Greer, Alexander
    Oxygen is inarguably among the most important molecules which sustain the majority of life as we know it. However, in its lowest excited state, singlet oxygen is a powerful cytotoxic agent capable of damaging DNA, proteins, and cell membranes. In medicinal context, production of singlet oxygen from light-activated drugs (photosensitizers) has been used to various degrees in photodynamic therapy to remove cancerous tumors, and in photodynamic inactivation of microorganisms to eliminate harmful pathogens. In the last decade, nanomaterials have emerged as a promising platform to establish control over the singlet oxygen production and advance the practical uses of photosensitization. Nevertheless, when compared to conventional chemotherapy as a means to treat diseases, or the use of common chemical agents to inhibit bacterial growth, application of nanomaterials for photodynamic processes in these areas is still in its infancy and substantial knowledge of understanding and controlling this approach is missing.The overarching goal of the work presented in this thesis is to provide molecular-level insight into the events taking place when nanomaterials are used to aid and manage photosensitized singlet oxygen production. To aid in this quest, the studies presented in this thesis looked at singlet oxygen generation from several common types of colloidal hybrid nanoparticle-photosensitizer materials. Silica- and liposome-based photosensitizing nanoparticles were employed to quantify singlet oxygen partition between the various local microenvironments inherent to each formulation, which fundamentally dictates the reactive species’ abilities to reach other substrates in solution or within the nanocarriers. Meanwhile, Ag and Au metal-based hybrid nanoparticles were used to understand how the metallic structure’s interactions with incident light can change the properties of a nearby photosensitizer and ultimately affect singlet oxygen generation.Methodologies, results, and conclusions discussed throughout the work presented herein aim to equip the research community with important layers of information to address the design of nanomaterials for photodynamic processes from the points-of-view of singlet oxygen and the photosensitizer. This in turn will enable the field to sort and tailor the countless possible hybrid nanoparticle-photosensitizer combinations for specific practical applications.
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    The formation of supported lipid bilayers on nanoparticles as tools to further explore plasmonic properties
    (2022-01-04) Schechtel, Shauna L; Heyne, Belinda JM; Prenner, Elmar J; Shi, Yujun
    Forming a bilayer of lipids on the surface of various nanoparticles has been gaining popularity in the literature since the initial study by Mornet et al. (2005). The initial supported lipid bilayer system was formed on silica nanoparticles and explored for applications such as drug delivery. However, the main limitation is that these systems are currently characterized predominantly by cryo-TEM. Based on the limited accessibility of cryo-TEM, the first goal explored within this thesis was to assess whether a supported lipid bilayer on silica nanoparticles could be characterized by other techniques. The results indicate that zeta potential and conventional transmission electron microscopy work as characterization tools to confirm the presence of a supported lipid bilayer on the surface of silica nanoparticles. With our new characterization approach, we expand our research to engineer a new nanoparticle supported lipid bilayer system, a silver core – silica shell supported lipid bilayer (Ag@SiO2 SLB). Silver was chosen as a core material because of its plasmonic properties. The Ag@SiO2 supported lipid bilayer was synthesized and characterized using dynamic light scattering, zeta potential and UV-VIS spectroscopy. A wide range of imaging techniques have also been implemented to obtain direct evidence of the lipid deposition on the surface of the nanoparticle, such as TEM, cryo-TEM, HR-TEM, staining and EDX. Despite our effort, direct evidence has yet to be obtained. Ag@SiO2 SLB was also investigated for its ability to enhance fluorescence via plasmonic effect. Herein, it was shown that the Ag@SiO2 SLB follows distance dependant fluorescence enhancement trends. Taken together a novel material was synthesized, characterization was expanded, and potential applications expanded the value of the SLB system.