Mollusc glue inspires the next generation of adhesives

Challenge: non-toxic, waterproof adhesive

Natural solution: Edible mussel Mytilus edulisTube of glue © Joel Kingsbury, www.sxc.hu

 

 

Adhesives have a vast range of uses from construction to dentistry.  However, many of the glues currently available contain formaldehyde, a known carcinogen. 1  Furthermore, few manufactured adhesives are capable of forming a strong bond in wet conditions.Mussel © Sarah Nuehring
 

 

 

 

 

 

Mussels are a type of mollusc commonly found on the seashore, usually firmly attached to a hard surface like a rock or man-made structure.  The mussel secures itself with a self-made glue. 2  This liquid adhesive quickly hardens into strong but flexible filaments that hold the animal in place despite battering waves.  The glue, consisting of long chains of protein molecules, can form incredibly strong bonds with a wide range of surfaces, and unlike man-made adhesives it can harden underwater. 3
 

 


officer workers © yufuyf, www.sxc.huAfter years of studying the chemical structure of mussel glue, scientists have succeeded in creating an adhesive that mimics it.  Based on soy protein, the new adhesive is not only strong and non-toxic but will set underwater. 4  It is already being used commercially in an environmentally-friendly brand of furniture.  The manufacturers claim that because their furniture does not use formaldehyde-based glue (unlike most wood panels)  it reduces indoor air pollution. 5  There has been increasing concern over recent years that formaldehyde and other volatile organic compounds used in construction materials may be present at harmful concentrations inside some buildings.  The implications of indoor air pollution for human health are still not fully understood. 6

 

 

The mussel-mimicking adhesive has also been combined with a fibrous material, itself inspired by the hair-like structures found on geckos' feet, to create a sticky tape that works even in wet conditions6  A further promising line of research is using the mussel-inspired glue to attach a non-stick coating to objects, creating a repellent surface. 7  Ironically, one of the major uses of such a product would be to prevent fouling of manmade underwater structures by aquatic creatures, including the mussels themselves.

 

mussels encrusting monitoring equipment © M McCormickMussel fouling is a major economic problem.  One study estimated that an infestation of zebra mussel in the Great Lakes cost the power industry alone 3.1 billion US dollars in the 1993-1999 period, with a total economic impact of more than 5 billion US dollars. 9 Mussels coat the inside of pipes, increasing maintenance costs in installations such as hydropower plants and irrigation systems and introducing an unpleasant taste to drinking water.  They interfere with leisure and commercial boating by fouling the bottom of vessels and docks.  Current control measures involve treating water with bleach or painting structures with a toxic protective coating.  This can have unwanted impacts on other aquatic life, including commercially important species. 10  The new repellent coatings would simply prevent mussels and other marine life sticking to the treated surfaces without any other adverse effects.  Biodiversity itself may have provided the resolution to this particular conflict between human activities and nature.mussel dish © Hobbes Yeo, www.sxc.hu

 

 

 

 

 

Edible mussels are an important component of biodiversity in beach habitats, playing a role in nutrient recycling and beach building, and providing food for birds. 11  They are also an important economic species.  Mussels have formed part of people’s diets since at least 6000 B.C.  They have traditionally been harvested from the wild, but in recent centuries mussel farming has become a major industry.  In 2002, the global farmed production of edible mussels was 446,000 tonnes. 12  Mussel habitat is shrinking as a result of sea level rise, coastal developments and construction of sea defences.  The UK Biodiversity Action Plan now includes strategies to protect the intertidal beach habitat. 13   The edible mussel, which has contributed so much to human society in the form of both nutrition and inspiration for technological advancement,  is currently still a common and widespread species.  Increasing conservation effort may be needed to keep it that way.  Other mussel species, for example the freshwater pearl mussel Margaritifera margaritifera, are already critically endangered. 14mussels on a beach © Morgan Noguellou

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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References

 

  1. International Agency for Research on Cancer. Accessed April 2010. 
  2. Tyler-Walters, H. (2008). Mytilus edulis, common mussel. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme   Accessed April 2010.
  3. Waite, J.H. et al (1981) Polyphenolic substance of Mytilus edulis: novel adhesive containing L-Dopa and Hydroxyproline.  Science 212: 1038 – 1040.
  4. Lee, H. et al (2007) Mussel-inspired surface chemistry for multifunctional coatings.  Science 318: 426 – 430
  5. Columbia Forest Products. Accessed April 2010.
  6. A.P. Jones (2002) Indoor air quality and health. Developments in Environmental Sciences: Air Pollution Science for the 21st Century.  Pages 57-115
  7. O’Neill, C.R. (1997) Economic Impact of Zebra Mussels – Results of the 1995 National Zebra Mussel Information Clearinghouse Study. Great Lakes Research Review Vol. 3, No. 1.   Accessed April 2010.
  8. Lee, H. et al (2007) A reversible wet/dry adhesive inspired by mussels and geckos.  Nature 448: 338-341
  9. Dalsin, J.L. et al (2002)  Mussel adhesive protein mimetic polymers for the preparation of nonfouling surfaces.  J. Am. Chem. Soc. 2003, 124: 4253 – 4258.  Available in full online. .  Accessed April 2010.
  10. Terlizzi, A. et al. (2001) Environmental impact of antifouling technologies: state of the art and perspectives. Aquatic Conservation: Marine and Freshwater Ecosystems 11: 311 - 317
  11. Richard F. Dame (1996) Ecology of Marine Bivalves: an ecosystem approach. CRC Press, Florida.   Accessed April 2010.
  12. Mytilus edulis information sheet. Food and Agriculture Organisation of the United Nations. Accessed April 2010.   
  13. Biodiversity Action Reporting System.  Accessed April 2010. 
  14. IUCN Red List.  Accessed April 2010. 


Further reading