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Bioinspired Histidine–Zn2+ Coordination for Tuning the Mechanical Properties of Self-Healing Coiled Coil Cross-Linked Hydrogels

Authors :
Isabell Tunn
Matthew J. Harrington
Kerstin G. Blank
Source :
Biomimetics, Vol 4, Iss 1, p 25 (2019)
Publication Year :
2019
Publisher :
MDPI AG, 2019.

Abstract

Natural biopolymeric materials often possess properties superior to their individual components. In mussel byssus, reversible histidine (His)–metal coordination is a key feature, which mediates higher-order self-assembly as well as self-healing. The byssus structure, thus, serves as an excellent natural blueprint for the development of self-healing biomimetic materials with reversibly tunable mechanical properties. Inspired by byssal threads, we bioengineered His–metal coordination sites into a heterodimeric coiled coil (CC). These CC-forming peptides serve as a noncovalent cross-link for poly(ethylene glycol)-based hydrogels and participate in the formation of higher-order assemblies via intermolecular His–metal coordination as a second cross-linking mode. Raman and circular dichroism spectroscopy revealed the presence of α-helical, Zn2+ cross-linked aggregates. Using rheology, we demonstrate that the hydrogel is self-healing and that the addition of Zn2+ reversibly switches the hydrogel properties from viscoelastic to elastic. Importantly, using different Zn2+:His ratios allows for tuning the hydrogel relaxation time over nearly three orders of magnitude. This tunability is attributed to the progressive transformation of single CC cross-links into Zn2+ cross-linked aggregates; a process that is fully reversible upon addition of the metal chelator ethylenediaminetetraacetic acid. These findings reveal that His–metal coordination can be used as a versatile cross-linking mechanism for tuning the viscoelastic properties of biomimetic hydrogels.

Details

Language :
English
ISSN :
23137673
Volume :
4
Issue :
1
Database :
Directory of Open Access Journals
Journal :
Biomimetics
Publication Type :
Academic Journal
Accession number :
edsdoj.f08a5826534345ce9aea0e399c9d874f
Document Type :
article
Full Text :
https://doi.org/10.3390/biomimetics4010025