High strength polyvinyl alcohol/polyacrylic acid (PVA/PAA) hydrogel fabricated by Cold-Drawn method for cartilage tissue substitutes

Poly (vinyl alcohol) (PVA) hydrogel has been considered as promising cartilage replacement materials due to its excellent characteristics such as high water content, low frictional behavior and excellent biocompatibility. However, lack of sufficient mechanical properties and cytocompatibility are two key obstacles for PVA hydrogel to be applied as cartilage substitutes. Herein, Polyacrylic acid (PAA) has been introduced into PVA hydrogel to balance these problems. Compared with pure PVA hydrogel, PVA/PAA hydrogel has the equal excellent biocompatibility, and its cell adhesion is significantly improved. In order to further improve the mechanical properties of hydrogels, Cold-Drawn treatment of hydrogels is performed in this paper. Compared to pure 12% PVA hydrogel, 40.8-fold, 50.8-fold, and 46.8-fold increase in tensile strength, tensile modulus, and toughness, respectively, which can be obtained from 12% PVA/PAA Cold-Drawn hydrogel. These biocompatible composite hydrogels have a great application potential as cartilage tissue substitutes.