Enhancement of mechanical behaviors of the 3D-printed polyvinyl alcohol-based scaffold by boric acid crosslinking

Polyvinyl alcohol (PVA)-based scaffold fabricated by fused deposition modeling (FDM) shows great potential in cartilage repair field. However, the limited mechanical properties after being swollen by water molecules in the body fluid hinder their applications. Herein, the boric acid is introduced to improve the mechanical behaviors of FDM-printed PVA-based scaffold. The ICP, FTIR, SEM, and swelling behaviors are utilized to explore the influence of boric acid concentration on the materials. The results indicate that the boric acid would form boronic ester-crosslinked PVA (B-PVA) and the density of the crosslink will increase at first then decrease with the boric acid concentration increases. As the concentration of boric acid is 1 %, the densest crosslink point in materials can be obtained. Then the fatigue, relaxation, and creep behaviors tests are carried out, which indicates that the crosslinking will improve the mechanical behaviors of scaffold at a great level. At last, the scaffold shows a good mineralization ability and excellent biocompatibility.