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Effect of Secondary Structure on Surface Adsorption of Peptides Open Access


Other title
Surface Adsorption
Secondary Structure
Type of item
Degree grantor
University of Alberta
Author or creator
Binazadeh, Mojtaba
Supervisor and department
Unsworth, Larry (Chemical and Materials Engineering)
Zeng, Hongbo (Chemical and Materials Engineering)
Examining committee member and department
Zeng, Hongbo (Chemical and Materials Engineering)
Xing, Malcolm (Mechanical Engineering)
McDermott, Mark (Chemistry)
Narain, Ravin (Chemical and Materials Engineering)
Unsworth, Larry (Chemical and Materials Engineering)
Department of Chemical and Materials Engineering
Chemical Engineering
Date accepted
Graduation date
Doctor of Philosophy
Degree level
Protein adsorption at the biomaterial-tissue interface has several detrimental consequences which undermines the widespread application of engineered materials. Herein, it was asked what role protein secondary structures play in the adsorption of peptides, as well as how these structures affect the physicochemical properties of the final adsorbed layer on bare gold (Au) and poly (ethylene glycol) (PEG) modified Au surfaces. To this end, α-helices and -sheets were induced in poly-L-Lysine (PLL) and persistence of these structures in solution and adsorbed state was confirmed by circular dichroism (CD). PLL adsorption to Au surfaces was monitored using quartz crystal microbalance with dissipation (QCM-D). PLL adsorption on bare Au resulted in higher initial adsorption rates for α-helices as compared to β-sheets but the final adsorbed amount of β-sheets was higher than α-helices regardless of solution salt concentration. Viscosities for films formed from α-helices were ~2x that of β-sheets films, regardless of solution ionic strength. β-sheets have higher zeta potential as compared to α-helices. The interaction energy between PLL and Au surface was found to be driven by electrostatic and van der Waals forces. Presence of PEG grafted brush layers on the Au surface drastically reduced the adsorbed amount of different PLL structures and PLL layers adsorbed on PEG coated surfaces had similar layer viscosities. To further understand PLL adsorption mechanism and adsorbed layer properties, the interacting forces between PLL-Au, PLL-PLL, PEG-mica, and PEG-PLL surfaces were studied by surface forces apparatus (SFA). SFA results revealed that the adhesion energy of β-sheet vs. Au and β-sheet vs. β-sheet was considerably more than α-helix vs. Au and α-helix vs. α-helix systems respectively. The substrate surface adhesion energy of β-sheet was more dependent on the solution salt concentration as compared to α-helix due to the higher electrostatic interactions of β-sheet PLL film with Au (higher zeta potential value of β-sheet PLL). It was found that presence of PEG grafted layer eliminated the PLL secondary structure effect on adsorption due to the purely repulsive force that governed the PEG vs. PLL interaction.
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
Poly (ethylene glycol) and Poly(carboxy betaine) Based Nonfouling Architectures: Review and Current Efforts. Mojtaba Binazadeh, Maryam Kabiri, and Larry D. Unsworth, Proteins at Interfaces III State of the Art. 2012, 621-643Inhibiting Nonspecific Protein Adsorption: Mechanisms, Methods, and Materials. Mojtaba Binazadeh, Hongbo Zeng, and Larry D. Unsworth, Biomaterials Surface Science. 2013, 45-55Effect of peptide secondary structure on adsorption and adsorbed film properties. Binazadeh, M., H. Zeng, and L.D. Unsworth, Acta Biomaterialia, 2013. 9 (5): p. 6403-6413Effect of Secondary Structure on Peptide Adsorption on End-grafted Polyethylene Oxide Layers. Binazadeh, M., H. Zeng, and L.D. Unsworth, Acta Biomaterialia. In pressUnderstanding the Effect of Secondary Structure on Molecular Interactions of Poly- L-Lysine with Different Substrates by SFA. Binazadeh, M., A. Faghihnejad, H. Zeng, and L.D. Unsworth, Biomacromolecules. In press

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File title: Surface forces in Peptide Adsorption to End-Tethered PEO: Effect of PEO and Protein Secondary Structure
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