Effect of poling direction of (Na0.5Bi0.5)TiO3 ceramics on the in vitro response of MC3T3-E1 preosteoblasts and bacteria

The use of smart materials as implantable devices for bone repair is an emerging field in which alternatives have been explored in the last decade, such as using piezoelectric ceramics to mimic bone self-healing ability using the direct piezoelectric effect (generation of charges under mechanical stress). Here, the feasibility of using (Na0.5Bi0.5)TiO3 dense ceramics as a potential biomaterial for bone repair was studied. The effect of poling di-rection on the osteogenic properties of (Na0.5Bi0.5)TiO3 ceramics was assessed through several indicators of osteoblast differentiation, including gene expression, cell morphology, and mineralization. An enhanced osteo-conductivity, reflected in a higher amount of calcium deposits and the presence of large filopodia and dendritic cell morphology was observed on the negative side compared to non-poled, positive side, and controls. Regarding the ability of (Na0.5Bi0.5)TiO3 ceramics to accelerate osteoblastic differentiation, after 14 days, the gene expression measured by real-time quantitative polymerase chain reaction showed an up-regulation of osteo-pontin and osteocalcin from exposure, usually expressed during the late stages of osteoblastic differentiation. In addition, the positive side surface generated an antibacterial ratio of almost 50% on gram + bacteria, possibly due to the interaction between the positively charged surface and the membrane's negatively charged bacteria. The results reported here show that tunable (Na0.5Bi0.5)TiO3 ceramics have osteoconductive and antibacterial properties suitable for bone repair applications. Further studies are needed to deepen the understanding of the effect of the polarization level on the osteogenic and antibacterial properties.