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Reinforcement of Shear Thinning Protein Hydrogels by Responsive Block Copolymer Self-Assembly

Glassman, Matthew J. and Chan, Jacqueline and Olsen, Bradley D. (2013) Reinforcement of Shear Thinning Protein Hydrogels by Responsive Block Copolymer Self-Assembly. Advanced Functional Materials, 23 (9). pp. 1182-1193. ISSN 1616-301X. PMCID PMC4283780.

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Shear thinning hydrogels are promising materials that exhibit rapid self-healing following the cessation of shear, making them attractive for applications including injectable biomaterials. Here, self-assembly is demonstrated as a strategy to introduce a reinforcing network within shear thinning artificially engineered protein gels, enabling a responsive transition from an injectable state at low temperatures with a low yield stress to a stiffened state at physiological temperatures with resistance to shear thinning, higher toughness, and reduced erosion rates and creep compliance. Protein-polymer triblock copolymers capable of the responsive self-assembly of two orthogonal networks are synthesized. Midblock association forms a shear-thinning network, while endblock aggregation at elevated temperatures introduces a second, independent physical network into the protein hydrogel. These reversible crosslinks introduce extremely long relaxation times and lead to a five-fold increase in the elastic modulus, significantly larger than is expected from transient network theory. Thermoresponsive reinforcement reduces the high temperature creep compliance by over four orders of magnitude, decreases the erosion rate by at least a factor of five, and increases the yield stress by up to a factor of seven. Combined with the demonstrated potential of shear thinning artificial protein hydrogels for various uses, this reinforcement mechanism broadens the range of applications that can be addressed with shear-thinning physical gels.

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Additional Information:© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Received: July 19, 2012; Revised: August 28, 2012; Published online: October 11, 2012. This research was supported by the U.S. Army Research Office under contract W911NF-07-D-0004. SANS measurements were performed at the Lujan Center at Los Alamos National Laboratory, supported by DOE Basic Energy Sciences under FWP #2012LANLE389. The authors would like to acknowledge Drs. Rex Hjelm and Monica Hartl for assistance with the SANS experiments. Access to a CD spectrophotometer was provided by the Biophysical Instrumentation Facility for the Study of Complex Macromolecular Systems (NSF-0070319 and NIH GM68762), and NMR and MALDI were performed at the MIT Department of Chemistry Instrumentation Facility (DCIF). The authors are grateful to Prof. Gareth McKinley, Ahmed Helal, and Dr. Simona Socrate for helpful discussions for compression experiments, and Chris Lam and Mark Belanger for machine shop assistance. M.J.G. was supported by an NIH Interdepartmental Biotechnology Training Program (2-T32-GM08334) and J.C. is supported by a Summer Undergraduate Research Fellowship (SURF) from Caltech Student-Faculty Programs.
Funding AgencyGrant Number
Army Research Office (ARO)W911NF-07-D-0004
Department of Energy (DOE)2012LANLE389
NIH Predoctoral Fellowship2-T32-GM08334
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
Subject Keywords:hydrogels; self-assembly; stimuli-responsive materials; hybrid materials; block copolymers
Issue or Number:9
PubMed Central ID:PMC4283780
Record Number:CaltechAUTHORS:20130329-100658463
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Official Citation:Glassman, M. J., Chan, J. and Olsen, B. D. (2013), Reinforcement of Shear Thinning Protein Hydrogels by Responsive Block Copolymer Self-Assembly. Adv. Funct. Mater., 23: 1182–1193. doi: 10.1002/adfm.201202034
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37687
Deposited By: Tony Diaz
Deposited On:10 Apr 2013 18:06
Last Modified:29 Oct 2019 19:58

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