Assistant ProfessorAssistant ProfessorB. Sc. (Western Ontario)
Ph D (Toronto)
Office Phone: (902)494-2320
Email: Sarah.Wells@dal.ca
Mechanical Properties of Biopolymers
Structural-mechanical relations in biopolymers such as elastin and collagen
are examined in order to determine the underlying mechanism(s) of elasticity
of these materials-and thereby to understand the functioning of the arteries,
ligaments, skin etc. which they make up. As well, research examines the
structural remodeling of these structures during development and maturation:
from fetal to adult life.
Our research examines the structural-mechanical relationships in biopolymers such as collagen and elastin. In particular, we are interested in the structure, mechanical properties and mechanisms of elasticity of "elastic fibers". These fibers form the main rubbery component in soft tissues such as ligaments and arteries, providing them with their elasticity: the ability to stretch and recoil with minimal energy loss. Elastic fibers are composed of two components: the amorphous polymer elastin which is deposited in a bead-like scaffold of microfibrils. Elastin is composed of long-chain molecules and its elastic properties are thought to be derived from (i) changes in entropy (unstretching of the coiled regions of the molecule, as in a rubber band), and (ii) hydrophobic interactions between these uncoiled regions and the surrounding tissue water. As well, there is growing evidence that the microfibrils may have a mechanical role. Although this is not yet defined, microfibrils do form the elastic component in primitive vertebrates and invertebrates: organisms that lack elastin. The long-term goal of this research is to examine the mechanisms of elasticity of elastic fibers: i.e. how the structure determines this feature.
To this end, we will focus on questions such as: What structural changes occur to the fine structure of elastic fibers during development? For instance, what are the changes in the relative amounts of microfibrils and elastin, and/or the content and stability of crosslinking in the elastin? Are the mechanical properties of the elastic fibers altered during development? Such mechanical changes may accompany developmental structural remodeling of the fibers. What are the mechanical properties and elastic mechanisms of microfibrils? Finally, are the underlying elastic mechanism(s) of elastic fibers are altered during development? For instance, do elastic tissues in developing (prenatal) animals rely more on elasticity derived from microfibrils than from the entropic and hydrophobic contributions seen in mature elastin?
To address these questions, we are performing structural, mechanical, and thermomechanical analyses on mammalian elastic tissues at increasing stages of development, and on the lobster aorta: an elastic tissue rich in microfibrils but (amazingly) devoid of elastin. Currently we are designing a mechanical/thermomechanical testing apparatus capable of monitoring, controlling and recording variables such as load, extension, and temperature of samples of elastic tissues.
By defining the mechanical properties of elastin-and how its elastic mechanisms change during development-this research will aid in the "tissue engineering" of arterial replacements.
Selected Publications
Last updated May 22, 2001