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Title: The effect of nanoscale and micron sized alumina and cobalt chromium particles on plasma membrane integrity
Author: Craven, Ruth Thurza
ISNI:       0000 0004 6349 8715
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2016
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Under optimum conditions, alumina ceramic-on-ceramic and cobalt chromium (CoCr) metal-on-metal prostheses have low wear rates with the generation of predominately nanoscale wear particles. Delayed type IV hypersensitivity reactions and pseudotumours have been reported in patients with metal-on-metal prostheses. In vitro studies have revealed that CoCr, and to a lesser extent, alumina wear particles induce cytotoxic, genotoxic, and pro-inflammatory responses. Little is known about the mechanism of how the wear particles induce toxic effects, in particular how particles interact with the cell membrane. The aim of this study was to determine if CoCr and alumina particles were able to damage the cell membrane with toxic consequences or whether they passed through the membrane and exerted toxic effects intracellularly. Cobalt chromium (mode size 40-49 nm) nanoscale particles were generated using a pin-on-plate tribometer and compared against commercially available micron sized CoCr (mode size 2-3 μm) particles. Micron sized alumina (mode size 400-450 nm) particles were isolated via filtration methods and nanoscale alumina (mode size 30-39 nm) particles were obtained from a commercially available source. All particle stocks were characterised using TEM, EDX, and compared against the published literature. The effect of the particles on the integrity of a model membrane was assessed using vesicle leakage assays. None of the particle types tested induced extensive vesicle leakage, even in the presence of 10% (v/v) serum, or with isolated membrane proteins incorporated into the lipid vesicles. Particle binding to a solid supported bilayer lipid membrane (sBLM) was assessed using quartz crystal microbalance with dissipation (QCM-D) methods. Weak interactions with the membrane were observed by an increase in the dissipation measurements. In the presence of serum and with isolated primary fibroblast membrane proteins within the sBLM, nanoscale and micron sized alumina particles bound to the membrane at particle concentrations of 10 and 100 μ However, this did not occur for the nanoscale and micron sized CoCr particles. These results demonstrated that the formation of a protein corona and the presence of membrane proteins are critical for alumina particle binding to a model membrane system. However, membrane binding does not necessarily correlate to particle toxicity. Further experiments, such as investigating if the particles are actively taken up by the cells, is required to understand the interaction of nanoscale a micron sized CoCr particles with the cell membrane.
Supervisor: Tipper, Joanne L. ; Jeuken, Lars ; Williams, Sophie Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available