Enhancing mechanical and biological properties of 3D-printed polylactic acid scaffolds by graphitic carbon nitride addition for bone tissue engineering

The practical application of biodegradable polylactic acid (PLA) scaffolds in bone tissue engineering necessitates further enhancements in mechanical properties, cell adhesion, cell viability, hydrophilicity, and degradation rate. Accordingly, this study investigates the effect of incorporating 1 wt% of graphitic carbon nitride (g-C₃N₄) nanosheets on different properties of PLA scaffolds fabricated via fused deposition modeling. Results obtained from differential scanning calorimetry revealed that the crystallinity increased moderately from 1.90 to 2.70% with the addition of g-C₃N₄. Also, incorporating g-C₃N₄ into the PLA matrix significantly reduced the water contact angle of pure PLA from 82.54° to 54.65°, reflecting a transition from a hydrophobic to a hydrophilic surface, enhancing the wettability of the scaffolds, which is crucial for improved cell interaction. Weight loss measurements after 35 days of immersion in the phosphate-buffered saline solution demonstrated that the degradation rate of PLA scaffolds was increased from about 1% to 3.5% after g-C₃N₄ incorporation. Moreover, cell adhesion and viability were significantly improved in the composite scaffolds. Mechanical evaluations indicated that the elastic modulus and compressive strength increased dramatically from 174 to 15 MPa for pure PLA to 435 and 33 MPa for the PLA/g-C₃N₄ composite, respectively. In summary, these results suggest that the incorporation of g-C₃N₄ into PLA scaffolds enhances their mechanical and biological performance, making them excellent candidates for possible use in bone tissue engineering applications.