Bacterial Nanocellulose-Chitosan-Gelatin-Hydroxyapatite Scaffolds for Bone Tissue Engineering

Bacterial nanocellulose (BNC) is highly biocompatible and has excellent mechanical properties, but lacks bioactive properties. In this study, scaffolds of BNC composites with suitable physical and biological properties for bone tissue regeneration were successfully fabricated through a simple, facile, cost-effective, and scalable method via biosynthesis by Acetobacter xylinum in a culture medium supplemented with chitosan (CS), gelatin (GT), and hydroxyapatite (HAp). BNC-CS-GT-HAp scaffolds displayed a good 3D architecture of interconnected porous structures with fiber networks and improved surface roughness upon HAp incorporation, with pore diameters of 384.5-457.4 µm on the surface and 467.5-498.7 µm in the interior, along with porosity of 66.0%-81.4%. Adding HAp to scaffolds at 0.1% to 0.2% (w/v) improved scaffold properties, such as compressive strength (MPa), thermal stability, and antibacterial properties. BNC-CS-GT-HAp scaffolds were biomineralized in a simulated body fluid for 21 days, producing bone-like apatite with a Ca/P ratio of 1.65-1.69. The in vitro study of MC3T3-E1 cells showed that BNC-CS-GT-HAp scaffolds facilitated cell adsorption, adhesion, and proliferation. They also promoted alkaline phosphatase (ALP) activity and extracellular matrix (ECM) mineralization. On day 21, the cell-seeded scaffolds showed significantly improved compressive strength compared to cell-free scaffolds. The results of this study suggest that BNC-CS-GT-HAp scaffolds could enhance osteoconductivity, possess desirable properties for bone tissue engineering, and provide a promising platform for future translational and in vivo studies.