Abstract:
:The jaws of the bloodworm Glycera dibranchiata consist principally of protein and melanin scaffolds with small amounts of unmineralized copper (Cu) and mineralized atacamite (Cu(2)Cl(OH)(3)) fibers in distinct regions. Remarkably, when tested in air, the regions containing unmineralized Cu are the hardest, stiffest, and most abrasion resistant. To establish the functions of jaw constituents in physiologically relevant environments, this study examines the effects of hydration on their response to indentation, scratching, and wear. Although all jaw regions are degraded by the presence of water, the ones containing unmineralized Cu are affected least. Notably, scratch depths in the bulk and the atacamite-containing regions double when wet, whereas the corresponding increase in the regions with unmineralized Cu is approximately 20%. The results support the view that Cu ions are involved in the formation of intermolecular coordination complexes, creating a cross-linked molecular network that is both mechanically robust and resistant to water ingress. Hydration effects are greatest during wear testing, rates of material removal in water being about three times those in air. The mechanism underlying accelerated wear is suspected to involve coupled effects of near-surface damage and enhanced water ingress, resulting in increased plasticization and susceptibility to plastic plowing.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Moses DN,Pontin MG,Waite JH,Zok FWdoi
10.1529/biophysj.107.120790subject
Has Abstractpub_date
2008-04-15 00:00:00pages
3266-72issue
8eissn
0006-3495issn
1542-0086pii
S0006-3495(08)70483-1journal_volume
94pub_type
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