Alexandria Digital Research Library

Adhesion beyond the interface : Molecular adaptations of the mussel byssus to the intertidal zone

Author:
Miller, Dusty Rose
Degree Grantor:
University of California, Santa Barbara. Biomolecular Science and Engineering
Degree Supervisor:
J. Herbert Waite
Place of Publication:
[Santa Barbara, Calif.]
Publisher:
University of California, Santa Barbara
Creation Date:
2015
Issued Date:
2015
Topics:
Biology and Materials science
Keywords:
Redox
Friction
Biomimetics
Cohesion
Adhesion
Mussels
Genres:
Dissertations, Academic and Online resources
Dissertation:
Ph.D.--University of California, Santa Barbara, 2015
Description:

The California mussel, Mytilus californianus, adheres robustly in the high-energy and oxidizing intertidal zone with a fibrous holdfast called the byssus using 3,4-dihydroxyphenyl-L-alanine (Dopa)-containing adhesive mussel foot proteins (mfps). There are many supporting roles to mussel adhesion that are intimately linked and ultimately responsible for mussel byssus's durable and dynamic adhesion. This dissertation explores these supporting mechanisms, including delivery of materials underwater, iron binding, friction, and antioxidant activity. As the outermost covering of the byssus, the cuticle deserves particular attention for its supporting roles to adhesion including the high stiffness and extensibility of the M. californianus byssal cuticle, which make it one of the most energy tolerant materials known. The cuticle's matrix-granule composite structure contributes to its toughness by microcracking between its harder granules and softer matrix.

We investigated delivery of cuticular material underwater, cohesion of cuticle proteins, and surface damage mitigation by cuticle protein-based coacervates. To investigate underwater material delivery, we made cuticle matrix mimics by coacervating a key cuticular protein, Mytilus californianus foot protein 1, mfp-1, with hyaluronic acid. These matrix mimics coacervated over a wide range of solution conditions, delivered concentrated material, settled on and coated surfaces underwater. Because the granules are composed of mfp-1 condensed with iron, we used the surface forces apparatus to investigate the effects of iron on the cohesion of mfp-1 from two different species of mussels and found that subtle sequence variations modulate cohesion.

Using the coacervate matrix mimics and, modeling the granules as a hard surface (mica), we investigated the wear protection of coacervated mfp-1/HA to mica under frictional shear and found that preventing wear depends critically on the presence of Dopa groups. In addition to cuticle-derived mechanisms for adhesion protection, we also tested for direct chemical mechanisms by tracking redox in the mussel adhesive plaques and found a persistent reservoir of antioxidant activity that can protect Dopa from oxidation. Overall, the mussel byssus represents an excellent model system for understanding adaptive mechanisms of both underwater adhesives and tough materials and I propose in this dissertation that these supporting mechanisms are intimately linked and ultimately responsible for the durable and dynamic underwater adhesion of mussels in the intertidal zone.

Physical Description:
1 online resource (144 pages)
Format:
Text
Collection(s):
UCSB electronic theses and dissertations
ARK:
ark:/48907/f36971s4
ISBN:
9781339219134
Catalog System Number:
990045865740203776
Rights:
Inc.icon only.dark In Copyright
Copyright Holder:
Dusty MIller
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