Fabrication of poly(lactic acid)/Ti composite scaffolds with enhanced mechanical properties and biocompatibility via fused filament fabrication (FFF)-based 3D printing

Ideal bone substitutes should ensure good integration with bone tissue and are therefore required to exhibit good mechanical stability and biocompatibility. Consequently, the high elastic modulus (similar to that of bone), thermoplasticity, and biocompatibility of poly(lactic acid) (PLA) make it well suited for the fabrication of such substitutes by fused filament fabrication (FFF)-based 3D printing. However, the demands of present-day applications require the mechanical and biological properties of PLA to be further improved. Herein, we fabricated PLA/Ti composite scaffolds by FFF-based 3D printing and used thermogravimetric analysis to confirm the homogenous dispersion of Ti particles in the PLA matrix at loadings of 5-20 vol%. Notably, the thermal stability of these composites and the crystallization temperature/crystallinity degree of PLA therein decreased with increasing Ti content, while the corresponding glass transition temperature and melting temperature concomitantly increased. The compressive and tensile strengths of PLA/Ti composites increased with Ti increasing loading until it reached 10 vol% and were within the range of real bone values, while the impact strengths of the above composites significantly exceeded that of pure PLA. The incorporation of Ti resulted in enhanced in vitro biocompatibility, promoting the initial attachment, proliferation, and differentiation of pre-osteoblast cells, which allowed us to conclude that the prepared PLA/Ti composite scaffolds with enhanced mechanical and biological properties are promising candidates for bone tissue engineering applications.