Synthesis, Structure, and Luminescent Properties of Europium-Doped Hydroxyapatite Nanocrystalline Powders

Abstract

The luminescent europium-doped hydroxyapatite (Eu:HAp, Ca10−xEux(PO4)6(OH)2) with0≤x≤0.2nanocrystalline powders was synthesized by coprecipitation. The structural, morphological, and textural properties were well characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The vibrational studies were performed by Fourier transform infrared, Raman, and photoluminescence spectroscopies. The X-ray diffraction analysis revealed that hydroxyapatite is the unique crystalline constituent of all the samples, indicating that Eu has been successfully inserted into the HAp lattice. Eu doping inhibits HAp crystallization, leading to a decrease of the average crystallite size from around 20 nm in the undoped sample to around 7 nm in the sample with the highest Eu concentration. Furthermore, the samples show the characteristic5D0→7F0transition observed at 578 nm related to Eu3+ions distributed on Ca2+sites of the apatitic structure.

Structural and Biological Assessment of Zinc Doped Hydroxyapatite Nanoparticles

“…ZnHAp was synthetized by a modified coprecipitation method [13]. ZnHAp samples, Ca 10− Zn (PO 4 ) 6 (OH) 2 , with Zn = 0, 0.07, and 0.1, respectively, were synthesized in air at a temperature of 80 ∘ C using aqueous solutions with various Zn : (Zn + Ca) ion ratios, the [Ca + Zn]/P ratio being maintained at 1.67 [13,14] …”

Photoluminescence and doping mechanism of theranostic Eu3+/Fe3+dual-doped hydroxyapatite nanoparticles

“…Due to its biocompatible and biodegradable properties, HAp has been regarded as one of the best host materials for metallic ions doping, such as Ag, Zn, Fe, Gd and Mn ions; the metallic ions doping could effectively regulate the properties of HAp and reduce the cytotoxicity from metallic ions [7–11]. Additionally, HAp could be a good host material for lanthanide doping by substitution of Ca 2+ with lanthanide ions into the HAp crystal lattice [7, 12]. The lanthanide doped HAp may endow the particles with fluorescent properties, which can overcome low fluorescence intensity and low photostability of traditional fluorescence dyes, and avoid toxicity and disposal issues of quantum dot probes [13].…”

“…The lanthanide doped HAp may endow the particles with fluorescent properties, which can overcome low fluorescence intensity and low photostability of traditional fluorescence dyes, and avoid toxicity and disposal issues of quantum dot probes [13]. It has been reported that lanthanide ions, such as europium and terbium, exhibited the typical fluorescence for cell imaging under the specific excitation wavelength [7, 12, 13]. In particular, doping of europium, which has 4 f-4 f intraorbital electronic transitions spanning the visible and near-infrared ranges, leads to an important material for biomedical applications in the near-infrared spectral range [11, 14].…”

Facile Synthesis, Characterization, and Cytotoxic Activity of Europium-Doped Nanohydroxyapatite

“…Ciobanu et al [11] reported similar results when preparing europium-doped hydroxyapatite nanocrystalline powders and reported that samples with 0.01 and 0.02 of europium are similar, from the XRD point of view, to the undoped hydroxyapatite; they also found that the relative intensities of the peaks decrease with the increment of the europium concentration (0.1, 0.2). On the other hand, Yang et al [12] found that the relative intensities of the diffraction peaks increase with the increasing of the pH values in the synthesis method (7, 9, and 12); this relation can be due to the enhanced crystallinity of the samples.…”

“…The doping of hydroxyapatite is possible because, as is known, the europium chemical reactivity is similar to that of calcium [10]. Ciobanu et al [11] reported the synthesis of doped hydroxyapatite nanoparticles synthesized at low temperature with the atomic ratio Eu/(Ca + Eu) = 1%, 2%, 10%, and 20% and ellipsoidal morphology. Yang et al [12] synthesized nanosized particles with multiform morphologies via a simple microemulsion-mediated process assisted with microwave heating and reported that the morphologies and the particle sizes of the made samples can be tuned by altering the pH values in the initial solutions.…”