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Generating bio-organic metal surfaces with modified surface properties using the type IV pilus of Pseudomonas aeruginosa Open Access

Descriptions

Other title
Subject/Keyword
surface modification
type IV pili
electron transfer
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Davis, Elisabeth M
Supervisor and department
Dr. Randall Irvin, Medical Microbiology and Immunology
Examining committee member and department
Stefan Pukatzki (Medical Microbiology and Immunology)
Mohammed El-Naggar (Physics, USC Dornsife)
Bart Hazes (Medical Microbiology and Immunology)
Edan Foley (Medical Microbiology and Immunology)
Dongyang Li (Chemical and Materials Engineering)
Department
Department of Medical Microbiology and Immunology
Specialization
Bacteriology
Date accepted
2013-01-07T09:35:43Z
Graduation date
2013-06
Degree
Doctor of Philosophy
Degree level
Doctoral
Abstract
Pseudomonas aeruginosa is an ubiquitiously distributed organism that functions as an aggressive opportunistic pathogen that has evolved to survive in many hosts in the plant and animal kingdoms and constitutes an important causative agent of nosocomial infections in terms of human health and serves as a major source of biofouling of surfaces in our environment. An important factor in the success of P. aeruginosa as a pathogen is its ability to colonize and move across various biotic and abiotic surfaces using its Type IV pilus (T4P). Binding is mediated by the receptor binding domain (RBD) and synthetic forms of the RBD irreversibly bind to stainless steel with high affinity in the absence of hydrophobic interactions. It was determined that the high affinity of the RBD for metal surfaces is mediated by electron sharing between the peptide and the metal surface electrons. Electron sharing results in the formation of a novel organo-metallic state of matter and creates new bio-organic metals that have altered surface properties (electron work function, adhesive force, corrosion, friction, propensity for biofilm formation) compared to unaltered metal. Chiral variants of the RBD peptide interact differentially with metal surfaces, suggesting that metal surfaces have chiral structural elements that are differentially recognized by the peptides. The addition of a PEG molecule to the RBD generates a facile, single-step versatile surface coating that increases the hardness of metals (304 stainless steel, titanium, A2024 aluminum) while decreasing corrosion, friction, and the propensity for colonization by bacteria. It was also demonstrated that the T4P of P. aeruginosa is an insulated molecular nanowire that facilitates electron removal from metal surfaces and can sustain the flow of high currents of up to several milliamps. The T4P also acts as a sensor, modulating current flow in response to external stimuli such as Pseudomonas autoinducers and ultra-violet light, and switches between conformations that permit or restricts electron transfer. The results in this study present attractive possibilities in industry for the facile generation of versatile surface engineering approaches for metals using non-toxic materials. The novel nanowire and environmental sensor aspects of T4P function have important implications in the pathogenesis of P. aeruginosa and further demonstrate the complexity and multifunctionality of the T4P.
Language
English
DOI
doi:10.7939/R3CK51
Rights
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Davis, E. M., Li, D. Y. & Irvin, R. T. (2011). A peptide-stainless steel reaction that yields a new bioorganic-metal state of matter. Biomaterials 32, 5311-5319Davis, EM., Li, DY., Shahrooei, M., Yu., B., Muruve, D., and RT Irvin. (2012). Evidence of extensive diversity in bacterial adherence mechanisms that exploit unanticipated stainless steel surface structural complexity for biofilm formation. Acta Biomaterialia  http://dx.doi.org/10.1016/j.actbio.2012.11.026

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