pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli

Proc Natl Acad Sci U S A. 2011 Feb 15;108(7):2651-5. doi: 10.1073/pnas.1015862108. Epub 2011 Jan 28.


Growing evidence supports a critical role of metal-ligand coordination in many attributes of biological materials including adhesion, self-assembly, toughness, and hardness without mineralization [Rubin DJ, Miserez A, Waite JH (2010) Advances in Insect Physiology: Insect Integument and Color, eds Jérôme C, Stephen JS (Academic Press, London), pp 75-133]. Coordination between Fe and catechol ligands has recently been correlated to the hardness and high extensibility of the cuticle of mussel byssal threads and proposed to endow self-healing properties [Harrington MJ, Masic A, Holten-Andersen N, Waite JH, Fratzl P (2010) Science 328:216-220]. Inspired by the pH jump experienced by proteins during maturation of a mussel byssus secretion, we have developed a simple method to control catechol-Fe(3+) interpolymer cross-linking via pH. The resonance Raman signature of catechol-Fe(3+) cross-linked polymer gels at high pH was similar to that from native mussel thread cuticle and the gels displayed elastic moduli (G') that approach covalently cross-linked gels as well as self-healing properties.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Bivalvia / chemistry*
  • Catechols / analysis
  • Catechols / metabolism*
  • Chromatography, Gel
  • Cross-Linking Reagents / metabolism*
  • Elastic Modulus*
  • Gels / chemical synthesis
  • Gels / metabolism*
  • Hydrogen-Ion Concentration
  • Iron / analysis
  • Iron / metabolism*
  • Polymers / chemical synthesis
  • Polymers / metabolism*
  • Rheology
  • Spectrum Analysis, Raman


  • Catechols
  • Cross-Linking Reagents
  • Gels
  • Polymers
  • Iron
  • catechol