Synthesis, phase stability of hydroxyapatite–silver composite with antimicrobial activity and cytocompatability

In the present study, the pH dependence hydroxyapatite (HAp) ceramics synthesis, and, their phase stabilities with respect to calcination temperatures were examined. Subsequently, HAp ceramics mixed with different silver amounts (HAp–Ag composites) were prepared in the temperature range 800–1200 °C to evaluate the phase stability of HAp in presence of silver. XRD results showed that as-synthesized HAp powder to be partially crystalline and are independent of pH of solution in the range of 9–11. These HAp phases remained stable even upto 1200 °C although crystallinity increased in all cases. Additional Ag peaks were appeared in HAp–Ag composites when the mixed powders were heated in the temperature range 800–1200 °C. FTIR result further confirmed the presence of Ca2+ and PO43− ions. TEM observation showed the precipitation of needle like HAp nanocrystals of 20–40 nm in length which agglomerated into particulate morphology above 800 °C. Antibacterial study of HAp–Ag composites on Staphylococcus aureus for 1, 3 and 5 wt% silver concentration showed that 3 wt% silver is sufficient to kill the surrounding bacteria. Further studies on NIH3T3 cells for HAp–Ag composites at 10 wt% silver of different concentrations showed good cytocompatibility compared to HAp indicates the prospective applications in therapeutic interventions.