Development of osteogenic chitosan/alginate scaffolds reinforced with silicocarnotite containing apatitic fibers.

The composite scaffolds of chitosan/alginate (CH-AL) reinforced by silicon-containing biphasic fibers were prepared through the freeze-drying method. The fibers were synthesized using a homogenous precipitation method under different reaction times and were characterized by XRD, FTIR, SEM, and ICP-OES. Fibers composed of two phases of hydroxyapatite and β-tricalcium phosphate (β-TCP) which remained the same once they were incorporated by 0.8 wt% silicon content (first group). However, with an increase in reaction time a new phase of silicocarnotite with 1.9 wt% Si associated with β-TCP phase (second group) was formed. The whisker-like fibers were 10-200 µm in the length and 0.2-5 µm in the width. The physicochemical, mechanical, and biological properties of composite scaffolds fabricating by adding different types and content of fibers were investigated. The scaffolds represented favorable microstructures with high porosity (66-88%) and interconnected pores varied between 40 and 250 µm. Significant improvement in the mechanical properties as well as the in vitro proliferation, mineralization and attachment of MG63 cells evaluated by MTT assay, alkaline phosphatase (ALP), and SEM was observed by adding fibers into the scaffolds. Silicocarnotite served as an osteogenic phase to stimulate cell proliferation, mineralization, and attachment. Fibers consisted of silicocarnotite also exhibited higher mechanical properties and water uptake compared to silicon incorporated fibers. Composite scaffolds reinforced by 50 wt% fibers precipitating in 8 days were superior in terms of mechanical properties and depicted compressive strength and modulus of 272 kPa and 4.9 MPa, respectively, which is 400% greater than CH-AL scaffolds. The results indicate that addition of silicon into the biphasic fibers which leads to the formation of silicocarnotite makes it a potential candidate as a constituent of composite scaffolds for bone tissue engineering.