Alendronate releasing silk fibroin 3D bioprinted scaffolds for application in bone tissue engineering: Effects of alginate concentration on printability, mechanical properties and stability

3D bioprinting uses biomaterials combined with cells to develop living constructs. This study explores the optimization of natural polymers, including silk fibroin, gelatin, and alginate, as bioink for 3D bioprinting in bone tissue engineering. The physicochemical properties of the bioink were thoroughly examined, revealing high water uptake and reduced degradation rate due to the addition of silk fibroin. The compressive modulus increased with higher alginate concentration. Rheological analysis confirmed shear-thinning properties and viscoelasticity of the ink. Through meticulous parameter optimization, the ink achieved the highest print accuracy with 4 % w/v alginate content. The printed scaffolds exhibited both macro and micro porosity, making them suitable for bone tissue regeneration. Furthermore, the scaffolds remained stable in culture medium for 36 days. The optimal composition for the hydrogel was determined to be a blend of 5 % fibroin, 7 % gelatin, and 4 % alginate in equal ratios. The bioink demonstrated excellent biocompatibility and, when supplemented with alendronate, enhanced alkaline phosphatase activity in MG-63 osteoblast-like cells. This finding indicates the commitment of cells toward the osteoblastic phenotype. Overall, this study successfully optimized the bioink and bioprinting process for bone tissue engineering applications, highlighting its promising potential for future advancements in the field.