The role of titanium dioxide on the morphology, microstructure, and bioactivity of grafted cellulose/hydroxyapatite nanocomposites for a potential application in bone repair

Fabrication and characterization of a novel 3D nanocomposite scaffold have been reported in this research. The purpose of developing this new 3D nanocomposite scaffolds is introducing an alternative treatment for bone tissue replacement. Outcomes confirmed that the morphology, microstructure and mechanical properties of synthesized 3D nanocomposite scaffolds closely mimics the properties of real bone tissue. The 3D nanocomposite scaffolds compose of nanoparticle hydroxyapatite which is embedded in the semi-IPN of polyacrylamide-grafted cellulose by free radical polymerization. TiO2 nanoparticles utilized as an auxiliary component. According to the SEM images the 3D nanocomposite were highly porous with maximum porosity of 87% inter connected with a pore size of around 70-130 μm. The FTIR spectrum and XRD pattern confirmed the graft polymerization process and the presence of TiO2 in the structure of 3D nanocomposite structures. A tensile test instrument measured elastic modulus and compressive strength of the samples. Comparing to the trabecular bone tissue, the nanocomposite scaffold with the highest content of TiO2 revealed the adequate compressive strength of 4.1 MPa. The in vitro swelling behavior of the scaffolds was determined in simulated body fluid for 72 h. Results suggested that increasing the amount of TiO2 decreases the swelling behavior of the nanocomposite scaffolds. The cytotoxicity of the scaffolds was determined by MTT assays on L929 cells. The results of cell culture experiments showed that the scaffold extracts do not have cytotoxicity in any concentration. Our results suggested that the introduced 3D nanocomposite scaffolds have a great potential as a bone tissue substitute.