Highly osteogenic and mechanically strong nanofibrous scaffolds based on functionalized multi-walled carbon nanotubes-reinforced electrospun keratin/poly(ε-caprolactone)

Here, we fabricated the electmspun scaffolds (so called PCL/Kr and PCL/Kr/CNT) based on poly(epsilon-caprolactone) (PCL), keratin (Kr), and carboxylated multiwalled carbon nanotubes (CNTs-COOH). Our goal was to evaluate the effect of CNTs-COOH on the osteogenic differentiation and mechanical and physicochemical properties of the scaffolds. We found that the addition of CNTs-COOH to the PCL/Kr scaffold reduced the average fiber diameter from 123 to 55 nm. As a result, the specific surface area of the scaffolds increased from 6 m(2)/g for the PCL/Kr scaffold to 15 m(2)/g for the PCL/Kr/CNT scaffold. Also, the PCL/Kr/CNT scaffold showed significantly higher tensile strength (8 vs 3 MPa) and modulus (114 vs 43 MPa) compared to the PCL/Kr scaffold. The formation of hydroxyapatite on the scaffolds incubated in simulated body fluid indicated the excellent osteoconductivity of the CNTs-containing scaffold. The presence of CNTs-COOH in the PCL/Kr/CNT scaffold also improved the osteogenic differentiation of mesenchymal stem cells as confirmed by the increased alkaline phosphatase activity and mineral formation on the surface of the scaffold. The PCL/Kr/CNT scaffold developed here can provide a mechanically strong construct with improved osteogenic properties for a variety of hard tissue engineering applications.