Effects of carbon doping on the microstructural, micro/nano-mechanical, and mesenchymal stromal cells biocompatibility and osteogenic differentiation properties of alumina

Abstract

It has been demonstrated that carbon (C) doped aluminium oxide (Al2O3) nanocomposite (C −0.012wt%) had greater wear resistance and lower surface grains pull out percentage when compared with monolithic Al2O3. In the present study, we investigated the physicochemical, micro- and nanomechanical, cell attachment, in vitro biocompatibility and osteogenic differentiation properties of Al2O3 doped carbon (0.012wt%) nanocomposite (Al2O3/C). Data were compared to values obtained for monolithic alumina (Al2O3). The calcined Al2O3/C nanocomposite was densified using cold isostatic pressing and followed by pressureless sintering. For physicochemical and microstructural characterisation, Energy dispersive X-ray (EDX), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoemission spectrometer (XPS) were used. EDX, XRD peaks and Raman spectroscopy demonstrated correlating to Al2O3/C. Surface profiling and contact angle investigations demonstrated highly contoured micro-surface topography. The micro and nano-hardness indicate an improved wear resistance of the Al2O3/C when compared with monolithic Al2O3. SEM, confocal images and alamar blue reduction assay suggested good cell attachment and proliferation of human bone marrow derived mesenchymal stromal cells (hBMSCs). Osteogenic protein and gene expression indicated Al2O3/C had a significant osteogenic potential (p<0.05) when compared with Al2O3. In conclusion, our novel Al2O3/C nanocomposite had improved mechanical properties. It also supports cell attachment and proliferation which are comparable to Al2O3. However, Al2O3/C has a significant osteogenic potential than that of Al2O3. These findings suggest that Al2O3/C nanocomposite is superior to Al2O3 and thus has a greater potential for use in orthopaedic applications.