Comparison of structural and antimicrobial activity between graphene oxide and reduced graphene oxide-reinforced hydroxyapatite-based nanocomposites for biomedical application

Hydroxyapatite (HAP) has been widely used in medical applications for the repair or replacement of bone tissues in the body. The constituents and structure of HAP are similar to those of bones and teeth. HAP shows comparatively inferior mechanical properties compared to natural bone. One of the best candidate materials for the reinforcing phase of HAP is graphene oxide (GO) and reduced graphene oxide (RGO), which exhibit excellent biocompatibility. Graphene oxide-hydroxyapatite (GO-HAP) and reduced graphene oxide-hydroxyapatite (RGO-HAP) bio-composites were fabricated with the objective of improving the morphological and structural properties of the biomaterial and future biomedical uses. The X-ray diffraction (XRD) analysis revealed the formation of GO-HAP and RGO-HAP nanocomposites, and the diffraction pattern of GO-HAP and RGO-HAP was analogous to the standard pattern of HAP. Fourier transform infrared spectroscopy confirmed the presence of functional groups in HAP, GO, RGO, GO-HAP and RGO- HAP. The flower-like morphology of the synthesized composites was investigated by field emission scanning electron microscopy. The relative quality of the nanocomposites is investigated by Raman spectroscopy and ultraviolet spectroscopy analyses. Energy-dispersive X-ray analysis provided the information that the Ca/P ratios of HAP, GO-HAP and RGO-HAP were 1.56, 1.60 and 1.59, which were close to the ratio of standard HAP, which is 1.67. The stability of the composites with respect to the temperature has been explored by thermogravimetric analysis. By performing an antibacterial investigation, the antimicrobial properties of GO-HAP and RGO-HAP against Bacillus subtilis and Staphylococcus aureus were observed. The cell viability of GO-HAP and RGO-HAP composites was analysed by performing an MTT assay against Vero cell lines. GO-HAP and RGO-HAP nanocomposites could be excellent alter- natives in the area of biomedical applications. (author)