Bioactivity and Biocompatibility Studies on Silk-Based Scaffold for Bone Tissue Engineering

Novel materials with promising properties can be used to achieve scaffold-based tissue engineering goals. Natural silk (NS) polymer has remarkable biomedical and mechanical properties as a material for bone tissue engineering scaffolds. This study describes the fabrication of a silk-based composite, in which natural silk and regenerated silk (RS) are combined to achieve better mechanical properties in the three-dimensional (3D) porous form. The biocompatibility and bioactivity of these scaffolds are evaluated. RS was made using mulberry-silk cocoons. RS/NS composite scaffolds were fabricated using the freeze-drying technique. Silk protein extract was evaluated by Fourier transform infrared spectroscopy (FTIR), with sharp amide peaks appearing at 1655 cm^(-1) and 1530 cm^(-1) in the FTIR spectrum, confirming the existence of fibroin. The fabricated 3D scaffolds were morphologically analyzed by scanning electron microscopy (SEM). An inter-connective spongy structure was found. Mechanical characterizations were carried out using a universal testing machine. Results show that the mechanical properties of the RS/NS composites are better than those of scaffolds fabricated with RS alone. In addition, in vitro tests, including those for cell viability and adhesion, were carried out with osteoblast cells by the MTT assay with a new calculation approach, which confirmed biocompatibility. The bioactivity potential of the RS and composites fibers was tested by introducing scaffolds to normal simulated body fluid for 21 days. Energy-dispersive X-ray spectroscopy and SEM analyses proved the existence of CaP crystals for both configurations. Thus, reinforced silk composite is a bioactive and biocompatible alternative for bone tissue engineering applications.