Efficient antibacterial activity of ternary nanocomposites containing hydroxyapatite, Co3O4, and cerium oxide

Metal oxide nanoparticles are routinely utilized in the biomedical field due to their diverse functionality. In particular, hybrid nanocomposites containing metal oxides possess a significant tunability of their chemical properties, as well as modifiable grain size and morphology. Hydroxyapatite (HA) and graphene oxide (GO) are already widely used in bone tissue engineering. We hypothesized that the addition of cobalt oxide or cerium oxide to form a hybrid nanocomposite with HA and GO can further enhance their properties toward cell viability and biodegradability. In this work, cobalt oxide/cerium oxide were individually combined with HA and GO to fabricate a ternary nanocomposite - HA/Co3O4/GO and HA/CeO2/GO for its potential use as a bone replacement hybrid material. The crystal structure of the resulting HA/Co3O4/GO composite was elucidated with XRD. The surface composition of the composite was analyzed using X-ray Photoelectron Spectroscopy and complex surface speciation was observed and assigned to Co(OH)2 and Co3O4. The particle length of HA in the composite was 35.5 ± 7.0 nm while the particle size of the cubic Co3O4 was 49.3 ± 10.8 nm, as revealed in TEM images. The antibacterial properties of HA/CeO2/GO were measured with the resulting inhibition area for E. coli and S. aureus of 15.9 ± 0.3 mm and 16.4 ± 0.2 mm, respectively. The ternary composite of HA/CeO2/GO and HA/Co3O4/GO showed an improvement in hardness of 4.1 ± 0.2 GPa and 3.2 ± 0.2. Summarily, HA/Co3O4/GO exhibited improved porosity, cell viability, and biodegradability compared with pristine HA. Overall, HA/Co3O4/GO nanocomposite possessed a porous structure and showed excellent antibacterial properties as well as controlled biodegradability and can be proposed as an improved bone-implant biomaterial. •TEM demonstrates HAP, and Co3O4 within GO with particle size of 8 nm for HAP.•HAP/Co3O4/GO shows cell viability value of 97.9 ± 2.4%.•The hardness value of HAP/Co3O4/GO composition is 4.1 ± 0.2 GPa.•The antibacterial of HA/Ce2O3/GO are 15.9 ± 0.3, 16.4 ± 0.2 mm for E. coli, S. aureus.