Correction: Preferential site substitution of Eu3+ ions in Ca10(PO4)6Cl2 nanoparticles obtained usinga microwave stimulated wet chemistry technique

International audience“In accordance with the rule of 2J + 1 at Cs symmetry a maximum of five sublevels should be present for the 5D0 → 7F1 andeight in the case of the 5D0 → 7F2 transitions whereas at C3 symmetry the 5D0 → 7F1 splits into two and the 5D0 → 7F2 into threeStark components.”Should have read:In accordance with the rule of 2J + 1 at Cs symmetry a maximum of three sublevels should be present for the 5D0 → 7F1 andfive in the case of the 5D0 → 7F2 transitions whereas at C3 symmetry the 5D0 → 7F1 splits into two and the 5D0 → 7F2 into threeStark components.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.2780

Structural modification of nanohydroxyapatite Ca10(PO4)6(OH)2 related to Eu3+ and Sr2+ ions doping and its spectroscopic and antimicrobial properties

The Eu3+ and Sr2+ ions co-doped hydroxyapatite nanopowders (Ca10(PO4)6(OH)2) were synthesized via a precipitation method and post heat-treated at 500 °C. The concentration of Eu3+ ions was established in the range of 0.5–5 mol% to investigate the site occupancy preference. The concentration of Sr2+ ions was set at 5 mol%. The structural and morphological properties of the obtained materials were studied by an X-ray powder diffraction, a transmission electron microscopy techniques and infrared spectroscopy. As synthesized nanoparticles were in the range of 11–17 nm and annealed particles were in the range of 20–26 nm. The luminescence properties in dependence of the dopant concentration and applied temperature were investigated. The 5D0 → 7F0 transition shown the abnormally strong intensity for annealed materials connected with the increase of covalency character of Eu3+–O2− bond, which arise as an effect of charge compensation mechanism. The Eu3+ ions occupied three possible crystallographic sites in these materials revealed in emission spectra: one Ca(1) site with C3 symmetry and two Ca(2) sites with Cs symmetry arranged as cis and trans symmetry. The antibacterial properties of Eu3+ and Sr2+ ions doped and co-doped hydroxyapatite nanopowders were also determined against Gram-negative pathogens such as Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli. Obtained results suggest that both europium and strontium ions may implement antibacterial properties for hydroxyapatites. In the most cases, better antibacterial effect we noticed for dopants at 5 mol% ratio. However, the effect is strongly species- and strain-dependent feature

Nanostructural Materials with Rare Earth Ions: Synthesis, Physicochemical Characterization, Modification and Applications

The success of nanotechnology in the field of physical, chemical and medical sciences has started revolutionizing the drug delivery science and theranostics (therapy and diagnostics) [...

Synthesis and Investigation of Physicochemical Properties and Biocompatibility of Phosphate–Vanadate Hydroxyapatite Co-Doped with Tb³⁺ and Sr²⁺ Ions

Searching for biocompatible materials with proper luminescent properties is of fundamental importance, as they can be applied in fluorescent labeling and regenerative medicine. In this study, we obtained new phosphate–vanadate hydroxyapatites (abbr. HVps) co-doped with Sr2+ and Tb3+ ions via the hydrothermal method. We focused on examining the effect of various annealing temperatures (500, 600 and 700 °C) on the spectroscopic properties and morphology of the obtained HVps. To characterize their morphology, XRPD (X-ray powder diffraction), SEM-EDS (scanning electron microscopy–energy-dispersive spectrometry), FT-IR (Fourier transform infrared) spectroscopy and ICP-OES (inductively coupled plasma–optical emission spectrometry) techniques were used. A further study of luminescent properties and cytocompatibility showed that the obtained HVps co-doped with Sr2+ and Tb3+ ions are highly biocompatible and able to enhance the proliferation process and can therefore be potentially used as fluorescent probes or in regenerative medicine

Review on Preformed Crowns in Pediatric Dentistry—The Composition and Application

The purpose of this review is to compare and contrast the various types of preformed crowns that can be used to restore the primary teeth in children. Historically, preformed crowns have been widely available for the past 50 years. The clinical performance of preformed crowns has evolved to meet higher functional, mechanical, and aesthetic demands. Preformed crowns are available in a range of prefabricated sizes and shapes. Preformed crowns can vary depending on their properties, compounds, methods of preparation, and biocompatibility

Preferential site substitution of Eu3+ ions in Ca10(PO4)6Cl2 nanoparticles obtained using microwave stimulated wet chemistry technique.

International audienceThe Eu3+ doped Ca10(PO4)6Cl2 nanocrystalline powders were synthesized using a microwave stimulated technique. Additional post heat treatment in the temperature range 800–1100 °C was applied in order to improve the crystallinity of the final product and eliminate the residual amorphous phase. Detailed structural characterization was performed by X-ray diffraction (XRD), Raman and infrared (IR) spectroscopy, transmission electron microscopy (TEM) and X-ray fluorescence (EDX). The optical properties of the Ca10(PO4)6Cl2 samples doped with different Eu3+ concentrations (0.5–5 mol%) were determined by measuring excitation, emission spectra and luminescence. TEM images confirmed the nanoscale nature of the final product with a primary particle size of about 60 nm and a hydrodynamic size of 200 nm when the product was dispersed in Milli-Q purified water (MQ) without further stabilization. The analysis of the 5D0 → 7F0 transition points out that for low concentration Ca(II) (A) site is preferentially substituted whereas increase of Eu3+ above 2 mol% results in domination of the Eu3+ cations located at Ca(I) (B) site. Increase of annealing temperature leads to an increase of the 5D0 → 7F0 intensity associated with the Eu3+ at A site. Preferential site substitution can be solved by analysis of the optical properties of the Eu3+ ion. The Judd–Ofelt parameters were calculated using simplified formalisms. The mechanism of concentration quenching process was identified as a dipole–dipole interaction

In Vitro Comparison of the Fluoride Ion Release from the First- and Second-Generation Fluoride Varnishes

Fluoride varnishes, both the first and the second generations, are effective in inhibiting caries, especially in children and adolescents, by reducing it on average by 43% for permanent teeth and 37% for deciduous teeth. The aim of this study was to evaluate the dynamics of in vitro fluoride ion release from first- (Duraphat) and second-generation (MI Varnish and Embrace Varnish) fluoride varnishes and the impact of the type of varnish, the time from its application and the pH of the environment on this process. Materials and methods: The test material (90 specimens), prepared from extracted human teeth, were divided into nine groups of 10 specimens each. Measured amounts of the examined varnishes were applied onto specimens and the levels of fluoride release were assessed at the baseline and after 1, 2, 24, 48 and 168 h from the application with the use of an ion-specific electrode. The specimens were immersed into artificial saliva with pH adjusted to 4, 5 and 7. The highest cumulative release of fluoride was obtained by MI Varnish (11.52 ppm/mg), regardless of the pH of the environment, whereas the lowest released fluoride concentration was achieved by Embrace Varnish (4.82 ppm/mg). In the acidic environment, the release of fluoride was significantly higher than in the neutral environment for all investigated varnishes, with no change in the overall fluoride release profile and with maximum fluoride release in the first two hours after application. The findings of this study indicate that all examined fluoride varnishes released the maximum amount of fluoride within the first hours after application and that it was related to the acidity of the immersion medium

Correction: Effects of crystalline growth on structural and luminescence properties of Ca (10−3x) Eu 2x (PO 4 ) 6 F 2 nanoparticles fabricated by using a microwave driven hydrothermal process

International audienc

The Study of Nanosized Silicate-Substituted Hydroxyapatites Co-Doped with Sr2+ and Zn2+ Ions Related to Their Influence on Biological Activities

Nanosized silicate-substituted hydroxyapatites, characterized by the general formula Ca9.8−x−nSrnZnx(PO4)6−y(SiO4)y(OH)2 (where: n = 0.2 [mol%]; x = 0.5–3.5 [mol%]; y = 4–5 [mol%]), co-doped with Zn2+ and Sr2+ ions, were synthesized with the help of a microwave-assisted hydrothermal technique. The structural properties were determined using XRD (X-ray powder diffraction) and Fourier-transformed infrared spectroscopy (FT-IR). The morphology, size and shape of biomaterials were detected using scanning electron microscopy techniques (SEM). The reference strains of Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa were used to assess bacterial survivability and the impact on biofilm formation in the presence of nanosilicate-substituted strontium-hydroxyapatites. Safety evaluation was also performed using the standard cytotoxicity test (MTT) and hemolysis assay. Moreover, the mutagenic potential of the materials was assessed (Ames test). The obtained results suggest the dose-dependent antibacterial activity of nanomaterials, especially observed for samples doped with 3.5 mol% Zn2+ ions. Moreover, the modification with five SiO4 groups enhanced the antibacterial effect; however, a rise in the toxicity was observed as well. No harmful activity was detected in the hemolysis assay as well as in the mutagenic assay (Ames test)