Novel fluoridated silk fibroin/ TiO₂ nanocomposite scaffolds for bone tissue engineering

It is known that Fluoride ions strongly affect bone mineralization and formation. In the present study, the engineered bone tissue scaffolds are fabricated using silk fibroin (SF) and flouridated TiO₂ nanoparticles. TiO₂ nanoparticles are modified by fluoride ions, and different levels (0, 5, 10, 15 and 20wt%) of the fluoridated TiO₂ nanoparticles (TiO₂-F) were subsequently added to the SF matrix through phase separation method to prepare silk fibroin/flouridated TiO₂ nanocomposite scaffolds (SF/TiO₂-F). Phase structure, functional groups, morphology and mechanical properties of the obtained scaffolds were evaluated by X-ray diffraction method (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and compressive testing, respectively. In vitro degradation studies of scaffolds were performed by incubating the samples in phosphate buffered saline (PBS) at 37°C and pH7.4 for 30days. Additionally, the bioactivity of scaffolds was estimated in a simulated body fluid (SBF) buffered at 37°C and pH7.4 for 28days. Moreover, MTT assay was used to confirm the biocompatibility of the scaffolds using human like SaOS-2 osteoblast cell line for 1, 3 and 5days. The obtained results indicated that the mechanical properties of scaffolds have been improved by increasing the TiO₂-F amount up to 15wt%. However, a detrimental effect was observed by a further increase in the TiO₂-F content. The bioactivity of SF/TiO₂-F nanocomposite scaffolds was promoted by flouridation of TiO₂. Furthermore, cell cytotoxicity results demonstrated that the SF/TiO₂-F nanocomposite scaffolds are nontoxic to osteoblasts. The cell fixation results after 3days of incubation revealed that the cell attachment and spreading on SF/TiO₂-F nanocomposite scaffolds are improved with respect to SF/TiO₂ nanocomposite scaffolds control sample.