Molecular Interactions between Luminescent Quantum Dots and Bacteria
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Date
2020-01-20
Type of Work
Department
Chemistry & Biochemistry
Program
Chemistry
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Distribution Rights granted to UMBC by the author.
This item may be protected under Title 17 of the U.S. Copyright Law. It is made available by UMBC for non-commercial research and education. For permission to publish or reproduce, please see http://aok.lib.umbc.edu/specoll/repro.php or contact Special Collections at speccoll(at)umbc.edu
This item may be protected under Title 17 of the U.S. Copyright Law. It is made available by UMBC for non-commercial research and education. For permission to publish or reproduce, please see http://aok.lib.umbc.edu/specoll/repro.php or contact Special Collections at speccoll(at)umbc.edu
Abstract
Luminescent semiconductor quantum dots (QDs) are continuously incorporated into bioassay, imaging, and treatment technologies. Cadmium-based QDs are commonly used in these technologies because of their superior optical properties - within the visible to near infrared wavelengths of light - compared to QDs made of other materials. However, concerns about cadmium toxicity have led to the increased use of protective coatings around cadmium-based QDs and to the development of QDs composed of more benign materials. The varying methods used to attain these QDs produce them with inherently different materials and structures. Additionally, QDs have varying homogeneous or heterogeneous surface chemistries. The QD surface may be either organic or aqueous-miscible; neutrally, positively, or negatively charged; and comprised of either short ligands, bulky biomolecules, or long polymeric chains. The different QD materials, structures, and surface chemistries impact whether QDs will associate with cells, and dictate what other interactions may occur after association. Our studies aim to concurrently investigate the impact that varying QDs' compositions have on their interactions with human and environmental health models in the context of antibacterial research. This context is important since there is currently a rise in the development of QD-based antibacterial treatments, which harness the inherent cytotoxic activity of QDs and steers it towards the rising onset of multidrug-resistant bacteria. Thus, this dissertations investigates the interactions of QDs with model liposomes, bacterial cells, and human red blood cells. We specifically compared the interactions of 1) CdSe core to ZnSe core QDs, 2) core QDs to ZnS-shelled QDs, 3) QDs with negatively charged ligand terminations to positively charged ligand terminations, and 4) core QDs of varying amine content surface coverage with these models. Various techniques - such as absorbance, emission, mass spectrometry, microscopy, dynamic light scattering, zeta potential, and FRET measurements - were used to characterize the QDs' compositions and their interactions with the biological models. These studies have increased our mechanistic understanding of the interactions between QDs and cells, how to control these interactions, and how to design future QD technologies to have intended interactions with targeted organisms while maintaining minimal impact on organisms which are essential to human and environmental health.