title: Forced protein unfolding leads to highly elastic and tough protein hydrogels.
abstract: Protein-based hydrogels usually do not exhibit high stretchability or toughness, significantly limiting the scope of their potential biomedical applications. Here we report the engineering of a chemically cross-linked, highly elastic and tough protein hydrogel using a mechanically extremely labile, de novo-designed protein that assumes the classical ferredoxin-like fold structure. Due to the low mechanical stability of the ferredoxin-like fold structure, swelling of hydrogels causes a significant fraction of the folded domains to unfold. Subsequent collapse and aggregation of unfolded ferredoxin-like domains leads to intertwining of physically and chemically cross-linked networks, entailing hydrogels with unusual physical and mechanical properties: a negative swelling ratio, high stretchability and toughness. These hydrogels can withstand an average strain of 450% before breaking and show massive energy dissipation. Upon relaxation, refolding of the ferredoxin-like domains enables the hydrogel to recover its massive hysteresis. This novel biomaterial may expand the scope of hydrogel applications in tissue engineering.
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Jie
authors.initials: J
authors.lastname: Fang
authors.affiliation: Physik Department E22, Technische Universität München, James-Franck-Strasse, Garching 85748, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Mehlich
authors.affiliation: Department of Biochemistry and Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA.
authors.forename: Nobuyasu
authors.initials: N
authors.lastname: Koga
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Jiqing
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Biochemistry and Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA.
authors.forename: Rie
authors.initials: R
authors.lastname: Koga
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Xiaoye
authors.initials: X
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Precision Measurements Technology and Instruments, School of Precision Instrument and Opto-Electronics Engineering, Tianjin University, Tianjin 30072, China.
authors.forename: Chunguang
authors.initials: C
authors.lastname: Hu
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Chi
authors.initials: C
authors.lastname: Jin
authors.affiliation: Physik Department E22, Technische Universität München, James-Franck-Strasse, Garching 85748, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Rief
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Juergen
authors.initials: J
authors.lastname: Kast
authors.affiliation: Department of Biochemistry and Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA.
authors.forename: David
authors.initials: D
authors.lastname: Baker
authors.affiliation: 1] Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1 [2] State Key Laboratory of Precision Measurements Technology and Instruments, School of Precision Instrument and Opto-Electronics Engineering, Tianjin University, Tianjin 30072, China.
authors.forename: Hongbin
authors.initials: H
authors.lastname: Li
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D002942:Circular Dichroism; D003545:Cysteine / Q000737:chemistry; D004548:Elasticity; D005288:Ferredoxins / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry*; D052898:Optical Tweezers; D015202:Protein Engineering; D058767:Protein Unfolding; D011506:Proteins / Q000737:chemistry*; D013314:Stress, Mechanical; D013718:Tensile Strength; D023822:Tissue Engineering
chemical_list: D001672:Biocompatible Materials; D005288:Ferredoxins; D020100:Hydrogels; D011506:Proteins; D003545:Cysteine