Effect of anions on the structural, morphological and dielectric properties of hydrothermally synthesized hydroxyapatite nanoparticles

Synthetic nano hydroxyapatites (HA) have been considered as potential biomaterials for bone tissue engineering applications because of its excellent biological properties. The present work deals with the synthesis of HA nanoparticles from different anion source materials via autoclave assisted hydrothermal method. All the prepared HA nanoparticles were characterized by X-ray diffraction (XRD), Fourier transformation infrared spectra, field emission scanning electron microscopy, energy dispersive spectra and high resolution transmission electron microscopy. The XRD patterns reveal the pure and hexagonal phase structure with smaller crystallite size for HA obtained from various calcium salt precursors. HA particles prepared from nitrate precursors show spherical morphology with 32 nm grain size whereas those derived from the acetate, chloride and egg shell precursors respectively show needle-like, irregular and oval morphology. The effect of different anions on the dielectric properties and alternating conductivity of HA is investigated, as a polarized surface can trigger biological reactions. For the particles obtained from nitrate, acetate, chloride and egg shell precursors respectively give dielectric constant (εʹ) values of 9.96, 13.22, 9.92 and 10.86 at 5 MHz. The εʹ and dielectric loss (εʹʹ) values for the HA nanoparticles decrease with increase in the applied frequency as well. The alternating current conductivity values confirm that the as-synthesized HA samples exhibit insulating behavior. In short this article provides the various applicability of HA particles in optoelectronics and drug delivery.Open access funding provided by the Qatar National LibraryScopu

In-vitro biocompatibility, bioactivity and photoluminescence properties of Eu3+/Sr2+ dual-doped nano-hydroxyapatite for biomedical applications

In the present investigation, we have successfully synthesized luminescent Eu3+-doped and Eu3+/Sr2+ codoped hydroxyapatite (HA) nanoparticles through sol-gel assisted precipitation method with the aim of developing novel biomaterials containing osteoblast mineral (Sr2+) and luminescence activator (Eu3+). The structure, morphology, thermal stability, and luminescence properties of the resultant spherical nanoparticles (50?100 nm diameters) were studied. Moreover, the in-vitro bioactivity of Eu0.1Sr0.1HA nanoparticles was investigated by immersing in the simulated body fluid for many weeks. The antimicrobial activity results against gram positive and gram negative bacterial stains, showed better resistivity for the Eu0.1Sr0.1HA among the other compositions. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay of live/dead cells cultured with Eu3+/Sr2+-doped HA nanoparticles retained its normal morphology and did not show a significant impact on cell proliferation at various incubation days, which evidence for the material's superior biocompatible nature even at a higher concentration of 375 ?g/mL. Thus, the incorporation of dual ions in HA nanoparticles with strong luminescence properties develops potential biomaterial for live cell imaging and in nanomedicine. ? 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2191?2201, 2018. ? 2017 Wiley Periodicals, Inc