Enhanced Biomineralization of Stem Cells and Adsorption of Extracellular Matrix Proteins on Bioactive Scaffold Reinforced with Carboxylated Multi-Walled Carbon Nanotubes

Tissue engineering creates a suitable substrate for the regeneration and repair of damaged bone tissue by providing scaffolds with the ability to stimulate bone formation. In this study, polycaprolactone (PCL) scaffold (scaffold A), PCL/keratin (Kr) scaffold (scaffold B), and PCL/Kr scaffold reinforced with carboxylated multi-walled carbon nanotubes (MWCNT-COOH) (scaffold C) were fabricated by electrospinning method and rapid osteogenic differentiation of mesenchymal stem cells and biomineralization on the scaffolds surface were evaluated. The bioactivity of scaffolds was investigated using energy dispersive x-ray spectroscopy (EDS) and inductively coupled plasma-optical emission spectroscopy (ICP-OES) and extracellular matrix proteins adsorption on the surface of scaffolds were also evaluated by BCA assay kit. Moreover, the effect of MWCNT-COOH on calcium deposition in the scaffolds were studied on days 7 and 14 of culture. The formation of hydroxyapatite layer on the scaffold C indicated the excellent osteoproductivity and bioactivity of scaffold. The amount of protein adsorption on the surface of scaffolds B and C was measured to be 32 μg/mm3 and 43 μg/mm3, respectively, which showed an increase in mesenchymal stem cells proliferation on the surface of scaffold C compared to the scaffold B. Also, high calcium deposition on the surface of scaffold C indicated mesenchymal stem cells differentiate into osteoblasts on the surface of scaffold. Therefore, the results of this study demonstrated that the PCL/Kr scaffold reinforced with MWCNT-COOH with excellent bioactivity, high protein adsorption, and osteogenic differentiation of mesenchymal stem cells can be a suitable candidate for bone tissue engineering applications.