Supramolecular hydrogels cross-linked by preassembled host\u2013guest PEG cross-linkers resist excessive, ultrafast, and non-resting cyclic compression

Xiaoyu Chen,Kunyu Zhang,Chaoqun Dong,Qian Feng,Bin Li,Yifei Yao,Liming Bian,Fengxuan Han,Kongchang Wei,Arthur Fuk-Tat Mak

doi:10.1038/s41427-018-0071-0

Abstract

Poly(ethylene glycol) (PEG)-based hydrogels are promising materials for biomedical applications because of their excellent hydrophilicity and biocompatibility. However, conventional chemically cross-linked PEG hydrogels are brittle under mechanical loading. The mechanical resilience and rapid recovery abilities of hydrogel implants are critical in load-bearing tissues, such as articular cartilage, which are routinely subjected to cyclic loadings of high magnitude and frequency. Here, we report the fabrication of novel supramolecular PEG hydrogels by polymerizing N,N-dimethylacrylamide with supramolecular cross-linkers self-assembled from adamantane-grafted PEG and mono-acrylated β-cyclodextrin. The resultant PEG–ADA supramolecular hydrogels exhibit substantial deformability, excellent capacity to dissipate massive amounts of loading energy, and have a rapid, full recovery during excessive, ultrafast, and non-resting cyclic compression. Furthermore, the energy dissipation capacity of the PEG–ADA (adamantane-grafted Poly(ethylene glycol)) hydrogels can be regulated by changing the concentration, molecular weight and cross-linking density of PEG. According to in vitro cell metabolism and viability tests, the PEG–ADA hydrogels are non-cytotoxic. When placed over a monolayer of myoblasts that were subjected to instantaneous compressive loading, the PEG–ADA hydrogel cushion significantly enhanced cell survival under this deleterious mechanical insult compared with the effects of the conventional PEG hydrogel. Therefore, PEG–ADA hydrogels are promising prosthetic biomaterials for the repair and regeneration of load-bearing tissues.

Highlights

Hydrogels are widely thought to be promising scaffold materials for tissue engineering and regenerative medicine[1,2,3,4]
The focus of this study is to investigate the mechanical properties of these supramolecular poly(ethylene glycol) (PEG) hydrogels, including deformability, energy dissipation, and fatigue resistance, in comparison with those of the chemical hydrogels cross-linked by conventional PEG diacrylate (PEGDA) and a co-monomer of identical concentrations, and cell behaviors responding to such unique mechanical properties
Mixing of ADA–PEG–ADA and monoAc-βCD yielded the supramolecular cross-linker of ac-β-cyclodextrin and adamantane (βCD–ADA)–PEG–ADA–Ac-βCD, which was selfassembled through efficient complexation between ADA and the βCD monomer, confirmed by the 2D-NOESY NMR analysis (Figure S5)[36]

Summary

Introduction

Hydrogels are widely thought to be promising scaffold materials for tissue engineering and regenerative medicine[1,2,3,4]. Extensive pioneering studies have been conducted to improve the stability and robustness of physical hydrogels. Meijer et al fabricated tough supramolecular hydrogels cross-linked by the H-bonds between selfcomplementary UPy units[13,14]. Scherman et al demonstrated the fabrication of supramolecular cross-linked hydrogels by the host–guest interactions of cucurbit [n] uril complexes[15,16,17]. In addition to their pioneering study on double-network hydrogels, Gong et al developed ionic bond-based polyampholyte hydrogels that possess excellent robustness and viscoelasticity[6,18,19,20,21].

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Results

Conclusion