Effect of Silicon Dioxide and Magnesium Oxide on the Printability, Degradability, Mechanical Strength and Bioactivity of 3D Printed Poly (Lactic Acid)-Tricalcium Phosphate Composite Scaffolds.

Abstract

Background: Poly (lactic acid) (PLA) is a biodegradable polyester that has been exploited for a variety of biomedical applications, including tissue engineering. The incorporation of β-tricalcium phosphate (TCP) into PLA has imparted bioactivity to the polymeric matrix.

Methods: We have modified a 90%PLA-10%TCP composite with SiO₂ and MgO (1, 5 and 10 wt%), separately, to further enhance the material bioactivity. Filaments were prepared by extrusion, and scaffolds were fabricated using 3D printing technology associated with fused filament fabrication.

Results: The PLA-TCP-SiO₂ composites presented similar structural, thermal, and rheological properties to control PLA and PLA-TCP. In contrast, the PLA-TCP-MgO composites displayed absence of crystallinity, lower polymeric molecular weight, accelerated degradation ratio, and decreased viscosity within the 3D printing shear rate range. SiO₂ and MgO particles were homogeneously dispersed within the PLA and their incorporation increased the roughness and protein adsorption of the scaffold, compared to a PLA-TCP scaffold. This favorable surface modification promoted cell proliferation, suggesting that SiO₂ and MgO may have potential for enhancing the bio-integration of scaffolds in tissue engineering applications. However, high loads of MgO accelerated the polymeric degradation, leading to an acid environment that imparted the composite biocompatibility. The presence of SiO₂ stimulated mesenchymal stem cells differentiation towards osteoblast; enhancing extracellular matrix mineralization, alkaline phosphatase (ALP) activity, and bone-related genes expression.

Conclusion: The PLA-10%TCP-10%SiO₂ composite presented the most promising results, especially for bone tissue regeneration, due to its intense osteogenic behavior. PLA-10%TCP-10%SiO₂ could be used as an alternative implant for bone tissue engineering application.