Facile synthesis of mechanically robust and injectable tetra-polyethylene glycol/methacrylate chitosan double-network hydrogel cartilage repair

The development of advanced hydrogel scaffolds with good biocompatibility, mechanical strength and bioactive property is highly desirable in cell growth, proliferation, and differentiation for the cartilage tissue regeneration. Herein, we reported a simple, inexpensive, feasible, and environmentally benign strategy to synthesize a biocompatible polyethylene glycol-based methacrylate-modified chitosan (PCSMA) double network (DN) hydrogel via the reversible Schiff base reaction and successive photopolymerization between the tetra-poly (ethylene glycol) aldehyde (Tetra-PEG-CHO) and methacrylate-modified chitosan (CSMA) in mild conditions. The four-terminated CHO groups were hypothesized to not only construct the whole architectural network through the dynamic pH-responsive Schiff base but also contribute to the injectable behavior and good tissue adhesion, which may furnish the surgeon with the availability of injectable and shapeless ability to fill in the gaps. Compared to the single PCS hydrogel with the main similar components of the tetra-PEG-CHO and pure CS moieties, the post-fabrication of PCSMA DN hydrogel possessed slower degradation time, denser network, and stronger mechanical stability, which could facilitate the bone marrow mesenchymal stem cell (BMSCs) activity and promote the chondrogenic differentiation for facilitating cartilage regeneration. Our study highlights the positive effects on chondrogenic performance and supports the PCSMA hydrogel as a promising tissue-engineered scaffold for the cartilage defect repair. •A using simple, inexpensive, and environmentally benign strategy is used for preparation of high-performance DN hydrogel.•An injectable hydrogel is developed with sensitive pH response and tailorable sol-gel transition.•DN hydrogel possesses favorable morphological structure, adhesive strength and degradation behavior.•DN hydrogel can promote cell growth, proliferation and chondrogenic differentiation for cartilage repair.