test Browse by Author Names Browse by Titles of Works Browse by Subjects of Works Browse by Issue Dates of Works

Advanced Search
& Collections
Issue Date   
Sign on to:   
Receive email
My Account
authorized users
Edit Profile   
About T-Space   

T-Space at The University of Toronto Libraries >
School of Graduate Studies - Theses >
Doctoral >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/26330

Title: Nanomechanics of Barnacle Proteins and Multicomponent Lipid Bilayers Studied by Atomic Force Microscopy
Authors: Sullan, Ruby May Arana
Advisor: Walker, Gilbert C.
Department: Chemistry
Keywords: multicomponent lipid bilayers
barnacle proteins
force mapping
AFM force spectroscopy
raft mimics
Issue Date: 23-Feb-2011
Abstract: Owing to atomic force microscopy’s (AFM) high-resolution in both imaging and force spectroscopy, it is very successful in probing not only structures, but also nanomechanics of biological samples in solution. In this thesis, the nanomechanical properties of lipid bilayers of biological relevance and proteins of the barnacle adhesive were examined using AFM indentation, AFM-based force mapping, and single-molecule pulling experiments. Through high-resolution AFM-based force mapping, the self-organized structures exhibited in phase-segregated supported lipid bilayers consisting of dioleoylphosphatidylcholine / egg sphingomyelin / cholesterol (DEC) in the absence and presence of ceramide (DEC-Ceramide) were directly correlated with their breakthrough forces, elastic moduli, adhesion, and bilayer thickness. Results were presented as two-dimensional visual maps. The highly stable ceramide-enriched domains in DEC-Ceramide bilayers and the effect of different levels of cholesterol as well as of diblock copolymers, on the nanomechanical stability of the model systems studied were further examined. For the proteins of the barnacle adhesive, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and chemical staining with amyloid-selective dyes, in addition to AFM imaging, indentation, and pulling experiments were performed to study the structure and nanomechanics of the polymerized barnacle glue. Nanoscale structures exhibiting rod-shaped, globular, and irregularly shaped morphologies were observed in the bulk barnacle cement by AFM. SEM coupled with energy dispersive x-ray (EDX) makes evident the organic nature of the rod-shaped nanoscale structures while FTIR spectroscopy on the bulk cement gave signatures of β-sheet and random coil conformations. Indentation data yielded higher elastic moduli for the rod-shaped structures as compared to the other structures in the bulk cement. Single molecule AFM force-extension curves on the matrix of the bulk cement often exhibited a periodic sawtooth-like profile, observed in both extend and retract portions of the force curve. Rod-shaped structures stained with amyloid protein-selective dyes (Congo Red and Thioflavin-T) revealed that about 5% of the bulk cement are amyloids.
URI: http://hdl.handle.net/1807/26330
Appears in Collections:Doctoral

Files in This Item:

File Description SizeFormat
Sullan_RubyMay_A_201011_PhD_thesis.pdf8.92 MBAdobe PDF

This item is licensed under a Creative Commons License
Creative Commons

Items in T-Space are protected by copyright, with all rights reserved, unless otherwise indicated.