Tetracalcium phosphate/porous iron synergistically improved the mechanical, degradation and biological properties of polylactic acid scaffolds.

Synergistically improving the mechanical and degradable properties of polylactic acid (PLA) scaffolds and endowing them with bioactivity are urgent problems to be solved in deepening their application in tissue engineering. In this work, tetracalcium phosphate (TTCP) and porous iron (pFe) were compounded by stirring and vacuum negative pressure, and then they were blended with polylactic acid and a porous scaffold (named TTCP@pFe/PLA) was prepared by selective laser sintering. On the one hand, molten polylactic acid penetrates the pores of porous iron to form an interlocking network, thereby achieving mechanical strengthening. On the other hand, the alkaline environment generated by the dissolution of tetracalcium phosphate can effectively catalyze the hydrolysis of polylactic acid to accelerate the degradation. Meanwhile, the dissolution of tetracalcium phosphate forms a local calcium-rich microenvironment, which rapidly induces apatite formation, that is, confers bioactivity on scaffolds. As a result, the TTCP@pFe/PLA scaffold exhibited a notable enhancement in mechanical strength, being 2.2 times stronger compared to the polylactic acid scaffold. More importantly, MC3T3E1 cells exhibit good adhesion, stretching, and proliferation on the composite scaffold, demonstrating good cytocompatibility. All these good properties of the TTCP@pFe/PLA scaffold indicate that it has potential applications as a novel alternative in bone tissue regeneration.

Tetracalcium phosphate/polycaprolactone composite scaffold: Mechanical reinforcement, biodegradability regulation and bioactivity induction.

Polycaprolactone (PCL) is considered a potential biomaterial due to its good biocompatibility, but its slow degradability and insufficient mechanical properties limit its wide application in bone tissue engineering. Tetracalcium phosphate's (TTCP) good degradability and inherent high stiffness are expected to compensate for the aforementioned defects of PCL and endow it with good biological activity. This goal of this study was to obtain bioactive PCL composite scaffolds with tuneable degradation properties and good mechanical strength via selective laser sintering technology (SLS). Composite porous scaffolds with TTCP contents of 0%, 5%, 10%, 15%, 20%, and 25% were prepared, and the experimental results showed that the addition of TTCP significantly improved the mechanical properties of the scaffold. Notably, the tensile strength of the composite scaffold with 20% TTCP content reached 15.2 MPa, which was 2.9 times that of pure PCL, and the best flexural strength was found in the scaffold with 15% TTCP content (4.7 MPa). More importantly, the introduced TTCP not only achieved the effective pH regulation of the soaking solution and the promotion of biodegradation, but also provided the scaffold with good bioactivity and biocompatibility.

Crosslinking of a polycaprolactone/tourmaline scaffold by sodium stearate with improved mechanical strength and bioactivity.

Although polycaprolactone (PCL) matrix composites have been extensively studied, the weak interface with nanofillers limits their further applications in bone tissue engineering. Herein, this study has designed a porous bone scaffold model using the triply periodic minimal surfaces (TPMS), and the optimal porosity was determined by comparing the mechanical properties. A sodium stearate-modified PCL/tourmaline (PCL/TM) composite scaffold with a strong interfacial effect was prepared by selective laser sintering technology. Wherein, sodium stearate acts as a bridge to improve the interaction between TM and PCL interface, while promoting its uniform dispersion. The results showed that the PCL/3% modified TM specimens exhibit the optimum mechanical properties, and their ultimate tensile and compressive strength increases by 21.8% and 32.1%, respectively, compared with pure PCL. The factors of mechanical enhancement of composite scaffolds can be elaborated from the construction of interface bridges. On the one hand, the carboxyl group at one end of sodium stearate will interact with the hydroxyl group on the surface of TM to enhance interfacial adsorption by forming ionic bonds and hydrogen bonds. On the other hand, the hydrophobic long chain at the other end of sodium stearate is universally compatible with hydrophobic PCL, thereby improving the dispersion of TM. These characteristics make the PCL/TM composite scaffold a valuable reference for its application in bone tissue engineering.