Extrusion-Based 3D Printing of Bioactive Cellulose Acetate−Hydroxyapatite Scaffolds for Osteogenic Regeneration

This study presents the development and characterization of cellulose acetate (CA) and CA reinforced with 5 wt % hydroxyapatite (CAHA5) as printable bioinks for extrusion-based 3D printing of scaffolds targeting bone tissue engineering. The printed scaffolds were evaluated for morphology, mechanical performance, surface characteristics, and biological response. Scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and energy-dispersive X-ray spectroscopy (EDS) confirmed scaffold integrity and successful HA incorporation, while contact angle, degradation, and swelling measurements revealed tunable surface wettability and fluid uptake. Mechanical testing under compression and tension showed that HA incorporation reduced strength and increased brittleness compared to pure CA, while stiffness values remained within reported ranges for printed scaffolds. Biological assays using mice mesenchymal stem cells (MSCs) showed favorable adhesion and osteogenic differentiation, particularly on CAHA5 scaffolds. These findings suggest that CAHA5 bioinks offer a promising route for fabricating biocompatible and osteoinductive scaffolds, where enhanced bioactivity is achieved despite a moderate reduction in mechanical strength compared to pure CA.