Synthesis and characterization of porous bioactive SiC tissue engineering scaffold

Silicon carbide (SiC) is an inert material with excellent biocompatibility properties. A major issue that limits its use as a medical device is the difficult processing technique that requires hot pressing at a temperature (>2,000^o C) and pressure (1,000-2,000 atm). In the present study, we developed a protocol to synthesize a porous SiC scaffold by pressing the powder at 50 MPa and heating at 900^o C/2 hr. The surface of SiC was chemically modified by NaOH to facilitate sintering and induce bioactivity. Porous discs with 51.51 ± 3.17% porosity and interconnected pores in the size range from 1 to 1,000 μm were prepared using 40% PEG. The average compressive strength and Young's modulus of the scaffolds were 1.94 ± 0.70 and 169.2 ± 0.08 MPa, respectively. FTIR analysis confirmed the formation of biomimetic hydroxyapatite layer after 2 hr of immersion in simulated body fluid. The Ca/P ratio was dependent on the concentration of the silanol groups created on the material surface. Increasing the atomic % of silicon on the SiC surface from 33.27 ± 9.53% to 45.13 ± 4.74% resulted in a 76% increase in the osteocalcin expression by MC3T3-E1 cells seeded on the material after 7 days. The cells colonized the entire thickness of the template and filled the pores with mineralized extracellular matrix after 14 days. Taken all together, the porous SiC scaffolds can serve as a bone graft for tissue reconstruction and cell delivery in trauma surgery.