A 3D-Printed Biomaterial Scaffold Reinforced with Inorganic Fillers for Bone Tissue Engineering: In Vitro Assessment and In Vivo Animal Studies

This study reports the design and evaluation of a 3D-printed alginate–polyethylenimine/silica (Alg–PEI/Si) hybrid biomaterial scaffold for bone tissue regeneration. The scaffold was fabricated using a 3D Bioplotter® and reinforced with inorganic fillers to enhance mechanical and biological performance. The Alg–PEI/Si scaffold demonstrated superior mechanical strength (60 MPa) compared to hydroxyapatite- or nanoclay-reinforced variants, with an optimized pore size (210 ± 10 µm) conducive to cell attachment and nutrient diffusion. In vitro tests with MG63 osteoblast-like cells confirmed high viability and confluence (up to 100% at day 7), and biomineralization in simulated body fluid verified calcium phosphate deposition. In vivo rabbit studies using BMP-7-loaded scaffolds showed complete bone regeneration by week 8, highlighting the scaffold’s mechanical stability, osteoconductivity, and bioactivity for critical-size defect repair.