Inorganic whiskers containing alkaline and bioactive ions enhance the comprehensive properties of 3D-printed biopolymer bone scaffold

Polylactic acid (PLA) has been widely studied as a scaffold material for bone tissue engineering, but still faces challenges, including as insufficient mechanical strength, slow degradation rate, and poor biomineralization and cellular response. In this study, PLA-based composite bone scaffolds incorporating basic magnesium sulfate whiskers (BMSW) at concentrations of 0, 2.5, 5.0, 7.5, and 10 wt% were fabricated via fused deposition modeling (FDM) 3D printing technology. The compression properties of the scaffolds increased with increasing BMSW content and peaked at 5 wt% BMSW, with the strength and modulus reaching 21.51 MPa and 297.38 MPa, respectively, 73% and 50% higher than those of PLA due to the reinforcing effect and uniform distribution of BMSW whiskers. The addition of BMSW accelerated the degradation of the PLA scaffold, with faster degradation observed at higher BMSW contents. Specifically, the alkaline ions (e.g. OH^-) released by BMSW neutralized the acidic products generated during the degradation of PLA, thereby accelerating the degradation of the scaffold through the synergistic effect of acid and base. Magnesium ions steadily released from BMSW degradation due to the encapsulation effect of the PLA matrix, and their release rate could be controlled by varying the BMSW content. The incorporation of BMSW also enhanced the biomineralization capacity of the composite scaffolds in simulated body fluid and promoted the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells, as confirmed by fluorescence and alkaline phosphatase staining. This study demonstrates that incorporating inorganic whiskers containing bioactive and alkaline ions into polymer can enhance its overall performance, making it more suitable for bone scaffold development.