The Physical and Antimicrobial Properties of Silver Doped Hydroxyapatite Sintered by Microwave and Conventional Sintering

In this paper, the silver-doped hydroxyapatite (AgHAp) nanoparticles were successfully synthesized by conventional and microwave sintering. The structural and antibacterial properties of AgHAp without heat treatment (AgHAp-90) and after heat treated at 800 and 1000 °C by conventional (AgHAp-800CS, AgHAp-1000CS) and microwave sintering (AgHAp-800MS, AgHAp-1000MS) were discussed respectively. The results of X-ray diffraction and fourier transform infrared spectroscopy suggested that the pure phase of AgHAp nanoparticles were obtained at 800 °C, but the β-TCP phase was observed when the temperature up to 1000 °C. Scanning electron microscopy images showed that the morphology and size of the nanoparticles changed with the improvement of temperature. The energy dispersive X-ray analysis identified the existence of Ag, Ca, P. The antibacterial test of AgHAp showed the excellent antimicrobial activity against gram-negative strains Escherichia coli and gram-positive strains Staphylococcus aureus. Also, the results showed the AgHAp had a smaller effect on gram-positive strains compare with gram-negative strains, and the antimicrobial activity of particles sintered by microwave was better than samples sintered by conventional. It showed the great advantages of microwave sintering. The silver ion releasing in solution was measured by the inductively coupled plasma and elucidated the results of antibacterial tests.