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.
Dual doped calcium apatite has been widely focused as it enhances the osteoconductive property for the possible applications in orthopedic and dental implants. In this work, we investigate the antimicrobial and bioactive properties of cerium/ strontium (Ce 3+ /Sr 2+ ) co-substituted hydroxyapatite (HA) nanoparticles synthesized by sol-gel assisted precipitation method. The structure, morphology, functional groups, photoluminescence, and thermal stability of the developed systems are examined. The comparative studies performed among the pure HA, Sr 2+ , and Ce 3+ -substituted HA nanoparticles illustrate higher antibacterial activity with lowered apatite-forming ability and biocompatibility for the Ce 3+ -substituted HA. However, the Ce 3+ /Sr 2+ co-substituted HA exhibits better biocompatibility, apatite-forming ability, and good antimicrobial properties. Sr 2+ ion inclusion leads to better biological properties and compromise the cytotoxic nature of the Ce 3+ -HA.In addition, the Ce 3+ /Sr 2+ -HA nanoparticles prevent thermal decomposition up to 700°C, pointing also toward the possibility of this co-substituted HA in bone implant applications. K E Y W O R D Sbioactivity, biocompatibility, hydroxyapatite, live cell imaging, Sol-gel
In the present investigation, we have successfully synthesized luminescent Eu -doped and Eu /Sr codoped hydroxyapatite (HA) nanoparticles through sol-gel assisted precipitation method with the aim of developing novel biomaterials containing osteoblast mineral (Sr ) and luminescence activator (Eu ). 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 Eu Sr HA 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 Eu Sr HA among the other compositions. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay of live/dead cells cultured with Eu /Sr -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 µg/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.
The present study aims to synthesize biocompatible and bioactive lanthanum (La3+)/strontium (Sr2+) dual ion doped hydroxyapatite (HA) nanomaterials by sol–gel method. The discrete substitution of La3+ and Sr2+ in pure HA enhances the osteoconductivity. The co-substitution of various La3+ concentrations (0.03, 0.06 and 0.1 M) regulates the physical and In Vitro properties. The study also investigates the effect of La3+/Sr2+ substituents on the crystalline property, microstructure, photoluminescence and In Vitro bioactivity of HA samples. La3+/Sr2+ co-substitution decreases the crystallite size of HA without any significant distortion of the crystal structure. In addition, the dual ions doping influences nanoparticles morphology by reducing the particle size from 75 to 20 nm. The In Vitro bioactivity tests for the La3+/Sr2+ co-substituted HA confirm the osteoconductive boneapatite generating capacity. Bactericidal tests against Staphylococcus aureus and Pseudomonas aeruginosa stains show better resistivity of La3+/Sr2+-HA samples. To authenticate the biocompatibility and antimicrobial activity of the synthesized La3+/Sr2+ dual doped HA nanoparticles for bone implant applications, different tests like cell viability and toxicity were conducted using human lung A549 cells.
Hydroxyapatite (Ca5(PO4)3OH) is a well-known bioceramics material used in medical applications because of its ability to form direct chemical bonds with living tissues. In this context, we investigate the biocompatibility and dielectric properties of Sr2+-substituted hydroxyapatite nanoparticles were synthesized by sol-gel method. The influence of strontium on the crystal structure, functional group, morphological, electrical properties, and biocompatibility of as-synthesized nano-hydroxyapatite samples was analyzed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FE-SEM). Dielectrical properties of the bioactive Sr-HA sample were investigated by a dielectric impedance spectroscopy method. The observed results illustrate the incorporation of Sr2+ ions in the apatite lattice could influence the pure HA properties, by reducing the crystallite size and crystallinity quite consistent with the morphology variation. The ac conductivity (σac) increased with an increasing applied frequency confirmed that prepared HA sample exhibited the universal power law nature. Further, the in vitro drug loading and release studies using doxycycline as a model drug demonstrate that the Sr2+ -HA nanoparticles show high drug adsorption capacity and sustained drug release. Thus, the improved bioceramics system could be a promising candidate for future biomedical applications.
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