On the implications of Si3N4 nanoparticle addition for the structural, mechanical, and biomedical properties of 3D-printed polycaprolactone (PCL) scaffolds for bone tissue regeneration purposes

This study is focused on the fabrication of composite scaffolds made of polycaprolactone (PCL) including different amounts of Si 3 N 4 nanoparticles (1, 3, 5, and 7 wt% %) by 3D-printing. Results showed that increasing the Si 3 N 4 content is associated with an increase in water uptake and enhanced surface biological activities. Water contact angle measurements showed a decreasing trend from 91.8° for pure PCL to 60.9° in PCL-7 % Si 3 N 4 . Results of compression tests showed that the PCL-5 % Si 3 N 4 composite scaffold had the highest compressive strength. Si 3 N 4 -containing scaffolds showed higher degradation rates, as compared with pure PCL scaffolds. Also, an apatite layer was formed on the surface of the 3D-printed scaffold in a simulated body fluid (SBF) after 21 days of immersion. The increased apatite density with increasing Si 3 N 4 suggested higher levels of bioactivity in composite scaffolds. MTT studies showed no toxicity and showed a great MG-63 cell adhesion over the surface, particularly in the PCL-5 % Si 3 N 4 scaffold. Additionally, this composite also demonstrated higher antibacterial properties when compared to pure PCL. These findings indicate that Si 3 N 4 -reinforced scaffolds are promising candidates for bone tissue regeneration with improved biological, mechanical, and biocompatibility properties.