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Cobalt cross-linked redox-responsive PEG hydrogels: from viscoelastic liquids to elastic solids

We describe cobalt cross-linked redox-responsive 4-arm histidine-modified PEG (4A-PEG-His) hydrogels, which can be switched from self-healing viscoelastic liquids to form stable elastic solids through a simple oxidation step from Co2+ to Co3+. The dramatic change in gel properties is quantified in r...

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Bibliographic Details
Main Authors: Wegner, Seraphine V. (Author) , Schenk, Franziska C. (Author) , Witzel, Sina (Author) , Spatz, Joachim P. (Author)
Format: Article (Journal)
Language:English
Published: 3 June 2016
In: Macromolecules
Year: 2016, Volume: 49, Issue: 11, Pages: 4229-4235
ISSN:1520-5835
DOI:10.1021/acs.macromol.6b00574
Online Access:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1021/acs.macromol.6b00574
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Author Notes:Seraphine V. Wegner, Franziska C. Schenk, Sina Witzel, Friedrich Bialas, and Joachim P. Spatz
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Summary:We describe cobalt cross-linked redox-responsive 4-arm histidine-modified PEG (4A-PEG-His) hydrogels, which can be switched from self-healing viscoelastic liquids to form stable elastic solids through a simple oxidation step from Co2+ to Co3+. The dramatic change in gel properties is quantified in rheological measurements and is associated with the altered ligand exchange rate of the cross-linking cobalt ions. While Co2+ forms kinetically labile coordination bonds with low thermodynamic stability, Co3+ forms kinetically inert and highly stable coordination bonds. Unlike the Co2+ cross-linked hydrogels, the Co3+ cross-linked hydrogels do not dissolve in buffer and swell overtime, where they remain intact longer with increasing gel connectivity, increasing polymer concentration and decreasing temperature. Remarkably, these gels can even resist the strong chelator EDTA and withstand both low and high pH due to the low ligand exchange rates in the primary coordination sphere. Overall, the Co2+/3+ redox pair provides an attractive platform to produce redox-responsive materials with big deviations in mechanical and chemical properties.
Item Description:Gesehen am 19.05.2020
Physical Description:Online Resource
ISSN:1520-5835
DOI:10.1021/acs.macromol.6b00574

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