Macroporous polyvinyl alcohol-tannic acid hydrogel with high strength and toughness for cartilage replacement

Polyvinyl alcohol (PVA) hydrogels as alternative materials for biomedical applications have attracted extensive attention. However, the development of bioactive hydrogel with macroporous structure and good mechanical performance is still an enormous challenge. In this study, a PVA-tannic acid (TA) macroporous hydrogel is presented by cryogelation method. The macropores are obtained by the large-sized ice crystals generated in situ. The pore size of the obtained hydrogel could reach 150–250 μm and the porosity is over 85%. The macroporous PVA-TA hydrogel exhibit notable compressive modulus (0.54 MPa), tensile modulus (0.70 MPa), compressive toughness (1.14 MJ/m3) and tensile toughness (1.49 MJ/m3). In addition, the hydrogel has remarkable self-recovery and energy dissipation ability. From the in vitro cell culture, it is observed that TA has strongly enhanced the bioadhesion and bioactivity of hydrogel, implying the potential application of PVA-TA hydrogel in cartilage replacement.Graphical abstract