Preparation and properties of T-ZnO_w enhanced BCP scaffolds with double-layer structure by digital light processing

Bone scaffolds require both good bioactivity and mechanical properties to keep shape and promote bone repair. In this work, T-ZnO_w enhanced biphasic calcium phosphate (BCP) scaffolds with triply periodic minimal surface (TPMS)-based double-layer porous structure were fabricated by digital light processing (DLP) with high precision. Property of suspension was first discussed to obtain better printing quality. After sintering, T-ZnO_w reacts with β-tricalcium phosphate (β-TCP) to form Ca₁₉Zn₂(PO₄)₁₄, and inhibits the phase transition to α-TCP. With the content of T-ZnO_w increasing from 0 to 2 wt%, the flexural strength increases from 40.9 to 68.5 MPa because the four-needle whiskers can disperse stress, and have the effect of pulling out as well as fracture toughening. However, excessive whiskers will reduce the cure depth, and cause more printing defects, thus reducing the mechanical strength. Besides, T-ZnO_w accelerates the deposition of apatite, and the sample with 2 wt% T-ZnO_w shows the fastest mineralization rate. The good biocompatibility has been proved by cell proliferation test. Results confirmed that doping T-ZnO_w can improve the mechanical strength of BCP scaffolds, and keep good biological property, which provides a new strategy for better bone repair.