Exploring Collagen I’s
Effect on the Elastic Modulus of Chicken Skin under Tensile Loading
Name: Leanne Grafmuller
Class: BE 210
This experiment will be conducted in order to examine the material
properties of chicken skin and determine if there is a trend between material
stiffness and collagen I content.
Samples will be tested under constant uniaxial
loading and from force-displacement data and stress-strain curves, elastic moduli will be determined.
These values will then be compared to their collagen content as
determined through comparison with a collagen type I standard marker in gel
electrophoresis. Collagen I’s cross-linked fibrous structure consists of 3 subunits
in a left-handed helix, 2 α1 chains and 1 α2 chain, rich in glycine, proline and hydroxyproline, are non-covalently linked in a
coiled-coil. These tropocollagen
molecules then aggregate into fibrils of parallel orientation and further
bundle together to form a periodic collagen fiber. Its repetitive amino acid sequence and its
consequent ropelike bonding provide for its high tensile strength. Collagen’s tightly bound structure is a
result of the many hydrogen and sulfide di-linkages
that occur periodically throughout the fiber and its subunits, causing the
addition of one subunit to provide more than one non-covalent linkage. It is the exponential increase of
non-covalent linkages that the addition of 1 collagen molecule to a fibril or 1
fibril to a fiber makes that suggest the amount of collagen present in skin
will have an exponential effect on its failure properties.