Combined effect of surface polarization and ZnO addition on antibacterial and cellular response of Hydroxyapatite-ZnO composites.

Bacterial infection is among the serious concerns in orthopaedic during/after surgery. Here, we demonstrate a novel technique to induce the antibacterial response in biomaterial substrates via surface polarization. In the present work, hydroxyapatite, HA-xZnO (x = 3.0, 4.5 and 7.5 wt. %) composites were processed by solid state sintering route at 1250 °C for 2 h. After phase evolution analyses, the detailed dielectric and electrical measurements were performed over a wide range of temperature (30-500 °C) and frequency (1 Hz-1 MHz). The impedance spectroscopic analyses suggest the activation energies for grains and grain boundaries for HA and HA-3 wt.% ZnO are (1.36, 1.44 eV), and (1.18, 1.98 eV), respectively. The sintered samples were polarized under polarizing temperature and voltage of 500 °C and 20 kV, respectively. The viability of Escherichia Coli (E. Coli) and Staphylococcus Aureus (S. Aureus) bacteria is observed to reduce significantly for polarized HA-x ZnO (x = 4.5 and 7.5 wt. %) composites as compared to their respective counterparts. On the other hand, polarization supports the proliferation of SaOS2 cells. Overall, the combination of surface polarization and optimal ZnO addition in HA has been demonstrated to significantly improve the antibacterial as well as osteoblast-like SaOS2 cellular response.