Impact of different transition metal ions in the structural, mechanical, optical, chemico-physical and biological properties of nanohydroxyapatite

Pure and metal ions (iron, manganese, cobalt) doped nanosized hydroxyapatite [Ca-10(PO4)(6)(OH)(2) or HA(P)] were prepared by wet-chemical precipitation technique. XRD patterns confirm that all the synthesized samples are single phase HA(P). Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) clearly showed the hexagonal and spherical morphology of the samples. X-ray photoelectron spectroscopy (XPS) confirmed that Fe2+, Mn2+, and Co2+ are substituted in HA(P) separately, and it also confirmed their oxidation state. The ac conductivity increases with the rise in frequency for all the samples. Among all dopants, 1% Fe doped HA D shows both the highest ac conductivity and the lowest impedance. The ac conductivity of the samples is in the order of 10(-6) S/m, and it remains the insulating nature of the pure and doped HA(P). The diamagnetic nature of the HA D changed into superparamagnetic due to the addition of dopant. The antibacterial activity of chosen samples depends on the types of bacterial strains and the dopant concentration. Among the different dopants 5% cobalt doped HA(P) revealed the highest antibacterial activity against Shigella dysenteriae bacteria.