title: pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli.
abstract: 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.
authors.affiliation: Department of Chemistry, Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA. holten@uchicago.edu
authors.forename: Niels
authors.initials: N
authors.lastname: Holten-Andersen
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Harrington
authors.forename: Henrik
authors.initials: H
authors.lastname: Birkedal
authors.forename: Bruce P
authors.initials: BP
authors.lastname: Lee
authors.forename: Phillip B
authors.initials: PB
authors.lastname: Messersmith
authors.forename: Ka Yee C
authors.initials: KY
authors.lastname: Lee
authors.forename: J Herbert
authors.initials: JH
authors.lastname: Waite
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000737:chemistry*; D002396:Catechols / Q000032:analysis / Q000378:metabolism*; D002850:Chromatography, Gel; D003432:Cross-Linking Reagents / Q000378:metabolism*; D055119:Elastic Modulus; D005782:Gels / Q000138:chemical synthesis / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000032:analysis / Q000378:metabolism*; D011108:Polymers / Q000138:chemical synthesis / Q000378:metabolism*; D012212:Rheology; D013059:Spectrum Analysis, Raman
chemical_list: D002396:Catechols; D003432:Cross-Linking Reagents; D005782:Gels; D011108:Polymers; D007501:Iron; C034221:catechol