Cooperative behavior of a sacrificial bond network and elastic framework in providing self-healing capacity in mussel byssal threads

• DOI: 10.1016/j.jsb.2016.07.020
• Publication Date: 2016-07-30T05:16:30Z
• Authors: Antje Reinecke; Luca Bertinetti; Peter Fratzl; Matthew J. Harrin...
• Keywords: Structure-Activity Relationship; Biopolymers; X-Ray Diffraction; Animals; Proteins; Protein Conformation, beta-Strand; 02 engineering and technology; 0210 nano-technology; Software; Bivalvia

The dissipative and self-healing properties of mussel byssal threads are critical for their function as anchoring fibers in wave-battered habitats and central to their emergence as an exciting model system for bio-inspired polymers. Much is now understood about the structure-function relationships defining this remarkable proteinaceous bio-fiber; however, the molecular mechanisms underlying the distinctive tough, viscoelastic and self-healing behavior are still unclear. Here, we investigate elastic and dissipative contributions from the primary load-bearing proteins in the distal region of byssal threads (the preCols) using X-ray diffraction (XRD) combined with in situ tensile testing. Specifically, we identified cross β-sheet structure in the preCol flanking domains that functions as an elastic framework, providing hidden length. Dissipative behavior was associated with a strain-rate dependent phase transition of a sacrificial network stabilized by strong, reversible cross-links. Based on these findings, we posit a new model for byssal thread deformation and self-healing.