Fabrication of BioMIL-4/Chitosan/Alginate-Based Nanocomposite Scaffolds for Bone Tissue Engineering

Tissue engineering has emerged as an alternative to typical graft surgeries in recent decades. This study focuses on exploring the potential of BioMIL-4, a biological metal-organic framework (BioMOF), and its composite with chitosan and alginate as natural polymers for the fabrication of scaffolds in bone tissue engineering. BioMIL-4 consists of calcium ions as metal nodes and alendronate, a drug used to treat osteoporosis by blocking osteoclast activity, as an organic ligand. Both components contribute to enhancing the bone healing process during the degradation of BioMOF. In the first step, a specific synthesis procedure was employed to achieve biomimetic mineralization of BioMIL-4 on chitosan nanofibers with varying weight ratios. This resulted in an increased degradation rate of BioMIL-4 and an improved mechanical strength of the natural polymer. Characterization analysis tests confirmed the successful synthesis of rod- and ribbon-shaped BioMIL-4 in the presence of chitosan nanofibers. In the second step, solutions of alginate and chitosan particles were added to the BioMIL-4/chitosan nanofibers with different weight ratios, followed by cross-linking using a CaCl2 solution. The complete scaffold was characterized by various techniques such as SEM, XRD, and FT-IR. The water absorption capacity of scaffolds ranged from 6 to approximately 10 times their initial weight. The scaffolds exhibited considerable biocompatibility, with cell viability exceeding 80% (assessed by MTT assay) after 72 h and reaching close to 100% in the best-case scenario. The porosity of the scaffolds was evaluated using the liquid displacement method, with values ranging from 82 to 94% across the three main scaffolds. Additionally, the degradation rate and mechanical strength of scaffolds were assessed, and the synergistic effects of biomimetic mineralization of BioMIL-4 on chitosan nanofibers, along with its proper blending with chitosan particles and alginate solutions, resulted in improvements in both parameters.