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Oxidatively Responsive Chain Extension to Entangle Engineered Protein Hydrogels

Tang, Shengchang and Glassman, Matthew J. and Li, Shuaili and Socrate, Simona and Olsen, Bradley D. (2014) Oxidatively Responsive Chain Extension to Entangle Engineered Protein Hydrogels. Macromolecules, 47 (2). pp. 791-799. ISSN 0024-9297. PMCID PMC4043348.

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Engineering artificial protein hydrogels for medical applications requires precise control over their mechanical properties, including stiffness, toughness, extensibility, and stability in the physiological environment. Here we demonstrate topological entanglement as an effective strategy to robustly increase the mechanical tunability of a transient hydrogel network based on coiled-coil interactions. Chain extension and entanglement are achieved by coupling the cysteine residues near the N- and C-termini, and the resulting chain distribution is found to agree with the Jacobson–Stockmayer theory. By exploiting the reversible nature of the disulfide bonds, the entanglement effect can be switched on and off by redox stimuli. With the presence of entanglements, hydrogels exhibit a 7.2-fold enhanced creep resistance and a suppressed erosion rate by a factor of 5.8, making the gels more mechanically stable in a physiologically relevant open system. While hardly affecting material stiffness (only resulting in a 1.5-fold increase in the plateau modulus), the entanglements remarkably lead to hydrogels with a toughness of 65 000 J m^(–3) and extensibility to approximately 3000% engineering strain, which enables the preparation of tough yet soft tissue simulants. This improvement in mechanical properties resembles that from double-network hydrogels but is achieved with the use of a single associating network and topological entanglement. Therefore, redox-triggered chain entanglement offers an effective approach for constructing mechanically enhanced and responsive injectable hydrogels.

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Additional Information:© 2014 American Chemical Society. Received: August 11, 2013; Revised: December 30, 2013; Published: January 16, 2014. This research was supported by the U.S. Army Research Office through the Institute of Soldier Nanotechnologies under Contract W911NF-07-D-0004. The authors thank Biophysical Instrumentation Facility at MIT (NSF-0070319) for the use of the CD spectrophotometer. M.J.G. was supported by an NIH Interdepartmental Biotechnology Training Program (2-T32-GM08334), and S.L. was supported by a Summer Undergraduate Research Fellowship (SURF) from Caltech Student-Faculty Programs.
Funding AgencyGrant Number
Army Research Office (ARO)W911NF-07-D-0004
NIH Predoctoral Fellowship2-T32-GM08334
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
Issue or Number:2
PubMed Central ID:PMC4043348
Record Number:CaltechAUTHORS:20140307-100711003
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Official Citation:Oxidatively Responsive Chain Extension to Entangle Engineered Protein Hydrogels Shengchang Tang, Matthew J. Glassman, Shuaili Li, Simona Socrate, and Bradley D. Olsen Macromolecules 2014 47 (2), 791-799
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44191
Deposited By: Tony Diaz
Deposited On:10 Mar 2014 15:26
Last Modified:03 Oct 2019 06:15

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