The toughness chitosan-PVA double network hydrogel based on alkali solution system and hydrogen bonding for tissue engineering applications

Biocompatibility and mechanical properties have always been important indicators for the application of hydrogel materials in tissue engineering. In this work, a high strength and toughness chitosan-poly (vinyl alcohol) (PVA) DN (double network) hydrogel based on multiple hydrogen bonding interactions was prepared by applying the simple freezing-heating alternate treatment to the chitosan-PVA alkaline solution. The PVA first network was prepared by freeze crystallization, and the chitosan second network was constructed by raising the chitosan/KOH/urea temperature to 45 °C. The dynamic hydrogen bonding presented in the first PVA network and the second chitosan network given the hydrogel superior compressive (60%-230 KPa), tensile (152 KPa-360%), recoverability (90.77% after 5 cycles) and anti-swelling properties. The results of in vitro cell compatibility and in vivo subcutaneous implantation in rats both indicated that the chitosan-PVA DN hydrogel had the ability to promote cell attachment and wound healing. This DN hydrogel based on hydrogen bonding is expected to be applied in the tissue engineering repair. In addition, the hydrogel preparation process is simple and non-toxic, which provides a reference for the production of green and safe tissue engineering hydrogels.