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

Schematic illustration of syntheses and characterizations of pure and different metal ions doped HAp nanoparticles and applied for antibacterial activity. [Display omitted] •Pure and metal ion doped nanosized hydroxyapatite were prepared by employing wet-chemical precipitation technique.•EDX spectra confirm the substitution of the dopants in HAP.•XPS spectra confirmed the presence of Fe2+, Mn2+, and Co2+ in HAP and their oxidation states.•Dielectric constant of HAP increases with the dopant concentration of Fe, Mn and Co.•The micro-hardness increases with the dopant concentration of Fe, Mn and Co.•In annealed samples Mn2+ and Co2+ doped HAp show superparamagnetic while Fe2+ doped HAp shows ferromagnetic nature. Pure and metal ions (iron, manganese, cobalt) doped nanosized hydroxyapatite [Ca10(PO4)6(OH)2 or HAP] were prepared by wet-chemical precipitation technique. XRD patterns confirm that all the synthesized samples are single phase HAP. 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 HAP 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 HAP 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 HAP. The diamagnetic nature of the HAP 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 HAP revealed the highest antibacterial activity against Shigella dysenteriae bacteria.