Hybrid PCL/Ha/Sep 3D Printed Scaffolds With Improved Surface and Bioactivity for Bone Tissue Repair

Abstract

Bone tissue engineering demands scaffolds that effectively balance printability, bioactivity, and structural stability. In this study, we developed binary biocomposite filaments based on poly(ε-caprolactone) (PCL) reinforced with hydroxyapatite (HA) and sepiolite (SEP) (total filler content of 20 wt%) for extrusion-based additive manufacturing of 3D scaffolds. The incorporation of HA/SEP increased melt viscosity and promoted a predominantly elastic behavior (G′ > G″), improving filament stability and shape accuracy during printing. Differential scanning calorimetry revealed a slight reduction in melting temperature with nearly unchanged crystallinity of PCL, whereas thermogravimetric analysis indicated a minor decrease in thermal stability upon filler addition. 3D printed scaffolds exhibited interconnected porosity and high geometric fidelity. An alkaline (NaOH) surface treatment effectively exposed the ceramic phases, decreased the water contact angle to ~60°, and significantly enhanced bovine serum albumin adsorption, indicating improved interfacial biofunctionality, as further confirmed by cell proliferation assay over 7 days. Under compression, composite scaffolds presented slightly lower elastic moduli than neat PCL but remained within the range reported for trabecular bone, suggesting sufficient early-stage mechanical support. Overall, the PCL/HA/SEP system integrates bone-mimetic chemistry with rheological control, providing a practical and manufacturable platform for bone tissue regeneration.