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Open AccessArticle

A Highly Stretchable, Tough, Fast Self-Healing Hydrogel Based on Peptide–Metal Ion Coordination

by Liang Zeng 1,†, Mingming Song 2,†, Jie Gu 2, Zhengyu Xu 2, Bin Xue 2,*, Ying Li 1,* and Yi Cao 2,*
Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China
Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Key Laboratory of Intelligent Optical Sensing and Manipulation, Ministry of Education, Department of Physics, Nanjing University, Nanjing 210093, China
Authors to whom correspondence should be addressed.
These authors contributed equally to this work.
Biomimetics 2019, 4(2), 36;
Received: 14 February 2019 / Revised: 31 March 2019 / Accepted: 6 May 2019 / Published: 10 May 2019
(This article belongs to the Special Issue Biogenic and Bioinspired Self-Healing Materials)
Metal coordination bonds are widely used as the dynamic cross-linkers to construct self-healing hydrogels. However, it remains challenging to independently improve the toughness of metal coordinated hydrogels without affecting the stretchability and self-healing properties, as all these features are directly correlated with the dynamic properties of the same metal coordination bonds. In this work, using histidine–Zn2+ binding as an example, we show that the coordination number (the number of binding sites in each cross-linking ligand) is an important parameter for the mechanical strength of the hydrogels. By increasing the coordination number of the binding site, the mechanical strength of the hydrogels can be greatly improved without sacrificing the stretchability and self-healing properties. By adjusting the peptide and Zn2+ concentrations, the hydrogels can achieve a set of demanding mechanical features, including the Young’s modulus of 7–123 kPa, fracture strain of 434–781%, toughness of 630–1350 kJ m−3, and self-healing time of ~1 h. We anticipate the engineered hydrogels can find broad applications in a variety of biomedical fields. Moreover, the concept of improving the mechanical strength of metal coordinated hydrogels by tuning the coordination number may inspire the design of other dynamically cross-linked hydrogels with further improved mechanical performance. View Full-Text
Keywords: self-healing; hydrogel; stretch-ability; metal ion coordination self-healing; hydrogel; stretch-ability; metal ion coordination
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MDPI and ACS Style

Zeng, L.; Song, M.; Gu, J.; Xu, Z.; Xue, B.; Li, Y.; Cao, Y. A Highly Stretchable, Tough, Fast Self-Healing Hydrogel Based on Peptide–Metal Ion Coordination. Biomimetics 2019, 4, 36.

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