Mechanical modeling of silk fibroin/TiO_2 and silk fibroin/fluoridated TiO_2 nanocomposite scaffolds for bone tissue engineering

摘要

Biocompatible and biodegradable three-dimensional scaffolds are commonly porous which serve to provide suitable microenvironments for mechanical supporting and optimal cell growth. Silk fibroin (SF) is a natural and biomedical polymer with appropriate and improvable mechanical properties. Making a composite with a bioceramicas reinforcement is a general strategy to prepare a scaffold for hard tissue engineering applications. In the present study, SF was separately combined with titanium dioxide (TiO2) and fluoridated titanium dioxide nanoparticles (TiO2-F) as bioceramic reinforcements for bone tissue engineering purposes. At the first step, SF was extracted from Bombyx mori cocoons. Then, TiO2 nanoparticles were fluoridated by hydrofluoric acid. Afterward, SF/TiO2 and SF/TiO2-F nanocomposite scaffolds were prepared by freeze-drying method to obtain a porous microstructure. Both SF/TiO2 and SF/TiO2-F scaffolds contained 0, 5, 10, 15 and 20 wt% nanoparticles. To evaluate the efficacy of nanoparticles addition on the mechanical properties of the prepared scaffolds, their compressive properties were assayed. Likewise, the pores morphology and microstructure of the scaffolds were investigated using scanning electron microscopy. In addition, the porosity and density of the scaffolds were measured according to the Archimedes' principle. Afterward, compressive modulus and microstructure of the prepared scaffolds were evaluated and modeled by Gibson-Ashby's mechanical models. The results revealed that the compressive modulus predicted by the mechanical model exactly corresponds to the experimental one. The modeling approved the honeycomb structure of the prepared scaffolds which possess interconnected pores.