Navigation Links
Mussels -- material artists with grip
Date:3/4/2010

We may like to eat mussels steamed in white wine, but we also like to find mussels at the beach. Mostly they are burrowed into the ground or tethered to rocks. But if you look closer you will find a mollusc which has adapted to life and nutrition in a special and fascinating way. Mussels thrive in rocky seashore habitats, in spite of the enormous physical demands present there. This is in no small part due to the evolution of the byssus, which mussels employ to tether themselves to accessible surfaces.

The individual byssal threads that compose the byssus are stiff, but stretchy and are fashioned by the mussel in a process resembling injection molding. Byssal threads are depended upon for dissipating the energy of crashing waves and also for resisting abrasive damage from water-borne debris. To this end, threads are sheathed with a thin and knobby outer cuticle; a biological polymer, which exhibits epoxy-like hardness, while straining up to 100% without cracking.

Incredible hardness and extensibility

Matthew Harrington, a researcher who worked on the project and Humboldt fellow at the Max Planck Institute for Colloids and Interfaces explains the motivation for studying the byssus cuticle: "Protective coatings are important for prolonging the lifetime of materials and devices. However, considering that hardness and extensibility are seldom coupled in engineered polymers or composites, understanding how one protects a flexible substrate becomes quite important." Byssal cuticles have a knobby appearance due to inclusions of submicron-sized granular structures in an apparently continuous matrix. Submicron-sized tears that form in the matrix during stretching of the cuticle are believed to hinder the formation of larger cracks that could lead to material failure.

Central to understanding the peculiar mechanical behaviour of the cuticle are the high concentration of iron ions in the cuticle and the presence of an uncommon modification of the amino acid tyrosine known commonly as dopa. Dopa is found at high concentrations in the main cuticle component, mussel foot protein-1 (mfp-1). Dopa is distinguished from typical amino acids due to its impressive affinity for complexing with transition metal ions, particularly iron. As Admir Masic, a scientist at the Max Planck Institute for Colloids and Interfaces who worked on the project, explains, "when 2-3 dopa residues complex with a single iron ion, they create an incredibly stable complex that can be utilized to cross-link structural proteins." These metal-protein complexes have a high breaking force (nearly half that of covalent bonds), but unlike covalent bonds they are reversibly breakable, making them ideal for creating sacrificial cross-links.

Cuticle is stabilized by dopa-iron complexes

Using a technique known as in situ Raman spectroscopy to probe the chemical composition of the cuticle, the researchers provided the first direct evidence that the cuticle is a protein-based polymeric scaffold stabilized by dopa-iron complexes. Moreover, it was discovered that the distribution of dopa-iron complexes is clustered, with areas of high density coinciding with the granular inclusions and low density with the inter-granular matrix. These observations, coupled with previous mechanical observations suggest that the densely cross-linked granules function as hard inclusions and the less cross-linked matrix functions in a sacrificial manner, allowing bonds to break prior to catastrophic failure.

"Nature has evolved an elegant solution to a problem that engineers are still struggling with; namely, how to combine the properties of abrasion resistance and high extensibility in the same material", says Peter Fratzl, director of the biomaterials department at the Max Planck Institute for Colloids and Interfaces. Apparently, the cuticle achieves this through a careful tailoring of protein-metal chemistry and the submicron organization of cross-link density. "Conceivably, this same strategy could be applied in engineered polymers and composites."


'/>"/>

Contact: Matthew Harrington
Matt.Harrington@mpikg.mpg.de
49-331-567-9429
Max-Planck-Gesellschaft
Source:Eurekalert

Related biology news :

1. Zebra mussels hang on while quagga mussels take over
2. The Prestige oil spill caused changes in the cell structure of mussels
3. Queens University Belfast works to save Strangford horse mussels
4. Mussels to determine how much contamination is in the ports
5. An electrifying discovery: New material to harvest electricity from body movements
6. New material mimics bone to create better biomedical implants
7. Bioengineered materials promote the growth of functional vasculature, new study shows
8. Supportive materials will help regenerate heart tissue
9. Tough yet stiff deer antler is materials scientists dream
10. NIEHS awards Recovery Act funds to focus more research on health and safety of nanomaterials
11. New beryllium reference material for occupational safety monitoring
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:1/30/2017)...   Invitae Corporation (NYSE: NVTA ... today announced that it will report its fourth quarter ... on Monday, February 13, 2017, and Invitae,s management team ... p.m. Eastern / 1:45 p.m. Pacific. ... financial results, guidance, and recent developments and will spend ...
(Date:1/24/2017)... NEW YORK , Jan. 24, 2017 /PRNewswire/ ... market study of the laboratory use of nuclear ... of 363 experienced end-users and profiled current practices, ... three years, as well as growth and opportunities. ... NMR, Instrument suppliers, NMR instruments, needs and innovation ...
(Date:1/19/2017)... and PUNE, India , January 19, 2017 ... Biometric Sensor Market, Opportunities and Forecast, 2014 - 2022," the global biometric ... CAGR of 9.6% from 2016 to 2022. In 2015, Asia-Pacific ... security for both public and private sectors. Continue ... ...
Breaking Biology News(10 mins):
(Date:2/24/2017)... 24, 2017  Driven by consumers, preference towards ... the fastest growing categories, finds the recently published ... Personal Care: Multi-regional Market Analysis and Opportunities ... firm Kline. "Biotechnology actives are derived ... more effective for skin and hair care applications," ...
(Date:2/24/2017)... 24, 2017  OncoSec Medical Incorporated ("OncoSec") (NASDAQ: ONCS), ... a Key Opinion Leader event to highlight new clinical ... poster presentation at the upcoming 2017 ASCO-SITC Immuno-Oncology Symposium ... will be held in-person and via live webcast on ... AM PST at the Lotte New York Palace Hotel ...
(Date:2/23/2017)... , Feb. 23, 2017  MIODx announced today ... two key immunotherapy technologies from the University of ... a method to monitor a patient for response ... and CTLA-4.  The second license extends the technology ... is likely to have an immune-related adverse event ...
(Date:2/23/2017)... ... February 23, 2017 , ... ... published evaluation of multiple immunoassay-based threat detection technologies by researchers from the ... CANARY® biosensor threat detection technology was found to have the best level ...
Breaking Biology Technology: