Objectives
The physicochemical properties and the tissue reaction promoted by microparticulated or nanoparticulated niobium pentoxide (Nb
2
O
5
) added to calcium silicate-based cement (CS), compared ...to MTA-Angelus
™
, were evaluated.
Materials and methods
Materials were submitted to the tests of radiopacity, setting time, pH, and calcium ion release. Polyethylene tubes filled with the materials were implanted into rats subcutaneously. After 7, 15, 30, and 60 days, the specimens were fixed and embedded in paraffin. Hematoxylin & eosin (H&E)-stained sections were used to compute the number of inflammatory cells (IC). Interleukin-6 (IL-6) detection was performed, and the number of immunolabeled cells was obtained; von Kossa method was also carried out. Data were subjected to ANOVA and Tukey test (
p
≤ 0.05).
Results
Nb
2
O
5
micro and Nb
2
O
5
nano provided to the CS radiopacity values (3.52 and 3.75 mm Al, respectively) superior to the minimum recommended. Groups containing Nb
2
O
5
presented initial setting time significantly superior than mineral trioxide aggregate (MTA). All materials presented an alkaline pH and released calcium ions. The number of IC and IL-6 immunolabeled cells in the CS + Nb
2
O
5
groups was significantly reduced in comparison to MTA in all periods. von Kossa-positive structures were observed adjacent to implanted materials in all periods.
Conclusions
The addition of Nb
2
O
5
to the CS resulted in a material biocompatible and with adequate characteristics regarding radiopacity and final setting time and provides an alkaline pH to the environment. Furthermore, the particle size did not significantly affect the physicochemical and biological properties of the calcium silicate-based cement.
Clinical relevance
Niobium pentoxide can be used as radiopacifier for the development of calcium silicate-based materials.
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CMK, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Aim
To evaluate the influence of the addition of microparticulate (micro) and nanoparticulate (nano) zirconium oxide (ZrO2) and niobium pentoxide (Nb2O5) to a calcium silicate‐based cement (CS) on ...the subcutaneous healing process in rats compared with MTA Angelus™.
Methodology
In each rat, two polyethylene tubes filled with the following materials: (i) MTA; (ii) CS + ZrO2micro; (iii) CS + ZrO2nano; (iv) CS + Nb2O5micro or (v) CS + Nb2O5nano were implanted subcutaneously; empty polyethylene tubes were used in the Control group. After 7, 15, 30 and 60 days, the specimens (n = 5 per group in each period) were fixed and embedded in paraffin. Masson's trichrome sections were used to obtain the volume density of the inflammatory cells (VvIC) and fibroblasts (VvFb). The sections were also stained with Picrosirius‐red to calculate the birefringent collagen content. Fibroblast growth factor‐1 (FGF‐1) was detected by immunohistochemistry, and the number of immunolabelled cells was obtained. The data were subjected to two‐way anova followed by Tukey's test (P ≤ 0.05).
Results
At all periods, the VvIC was significantly lower (P < 0.001) in all the CS and Control groups than in the MTA group. At all periods, the VvFb was reduced significantly (P = 0.023) in the MTA group in comparison with the other groups. In addition, the number of immunolabelled cells in the capsules of the CS groups was significantly higher (P < 0.001) than in the MTA group at all time‐points.
Conclusions
The experimental materials (CS + ZrO2 and CS + Nb2O5) induced fibroblast proliferation and accelerated the regression of the inflammatory reaction. However, the addition of nanoparticulate radiopacifiers did not improve the biological properties of a calcium silicate‐based cement when compared to microparticulate agents.
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BFBNIB, CMK, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Ceria (CeO
2
) is a promising dilute magnetic semiconductor. Several studies report that the intrinsic and extrinsic structural defects are responsible for room temperature ferromagnetism in undoped ...and transition metal doped CeO
2
nanostructures; however, the nature of the kind of defect necessary to promote and stabilize the ferromagnetism in such a system is still a matter of debate. In the work presented here, nanorods from the system Ce
1−
x
Cu
x
O
2−
δ
with
x
= 0, 0.01, 0.03, 0.05 and 0.10, with the more stable {111} surface exposed were synthesized by a microwave-assisted hydrothermal method. A very careful structure characterization confirms that the Cu in the samples assumes a majority 2+ oxidation state, occupying the Ce (Ce
4+
and Ce
3+
) sites with no secondary phases up to
x
= 0.05. The inclusion of the Cu
2+
in the CeO
2
structure leads to the introduction of oxygen vacancies in a density proportional to the Cu
2+
content. It is supposed that the spatial distribution of the oxygen vacancies follows the Cu
2+
distribution by means of the formation of a defect complex consisting of Cu
2+
ion and an oxygen vacancy. Superconducting quantum interference device magnetometry demonstrated a diamagnetic behavior for the undoped sample and a typical paramagnetic Curie-Weiss behavior with antiferromagnetic interactions between the Cu
2+
ions for the single phase doped samples. We suggest that the presence of oxygen vacancies is not a sufficient condition to mediate ferromagnetism in the CeO
2
system, and only oxygen vacancies in the surface of nanostructures would lead to such a long range magnetic order.
Ceria (CeO
2
) is a promising dilute magnetic semiconductor. The ferromagnetic order has proven to be an surface effect.
Nanomaterials with antimicrobial activity are promising alternatives to overcome microbial resistance in medical devices. Catheters, probes, and wound dressings are among the medical devices mostly ...affected by microbial contamination and the formation of polymicrobial biofilms. Nanoparticles (NPs) derived from natural sources, such as chitosan nanoparticles (CsNPs), and metal‐based nanoparticles, including silver nanoparticles (AgNPs), are receiving increased interest in nanomedicine. CsNPs have been widely explored as a coating material and antimicrobial agent. AgNPs have a strong antimicrobial effect against bacteria and fungi. The nanocomposite chitosan–silver nanoparticles (Cs‐AgNPs) can be more effective against several microorganisms, including multidrug‐resistant bacteria, due to the synergistic effect between chitosan and silver. This review addresses the most used synthesis methods, including green routes, to produce CsNPs, AgNPs, and Cs–AgNPs. It also discusses physicochemical characteristics and antimicrobial properties of these NPs in medical, pharmaceutical, and biotechnological areas.
Given the new challenges arising from the resistance of pathogens to commonly used antibiotics and innovations in medicine regarding the use of nanomaterials, this review examines the perspectives of using chitosan, silver, and the composite chitosan–silver nanoparticles to prevent biofilm formation. It also covers the physicochemical and antimicrobial properties of these alternative nanomaterials in medical, pharmaceutical, and biotechnological applications.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
ZnO-based materials are one of the most studied systems. Their applicability spans over several research areas and industries, like optoelectronics, catalysis and spintronics. Here we demonstrate the ...feasibility to prepare Co-doped ZnO thin films (Zn
1−
x
Co
x
O, with
x
= 0; 0.01; 0.03 and 0.05) deposited by the dip-coating technique, a very simple and a low-cost process. We focus the structural and the optical characterization in the context of dilute magnetic materials. Detailed analyses were carried out to investigate alternative sources of ferromagnetism, such as secondary phases and nanocrystals embedded in the nanostructured thin films. Conjugating different techniques, we confirmed the Zn replacement by Co ions in the ZnO wurtzite structure with no secondary phases up to
x
= 0.05. It was further observed that the major structural defects in the films are oxygen vacancies (V
O
) and zinc interstices (Zn
i
), and that the relative densities of these defects increase with the increase in Co concentration, which promotes the studied thin films to candidates to present room temperature ferromagnetism.
We demonstrate the feasibility to prepare Co-doped ZnO thin films (Zn
1−
x
Co
x
O,
x
= 0; 0.01; 0.03 and 0.05)
via
the dip-coating technique, a very simple and a low-cost process. We focus the structural and the optical analyses in the context of the DMOs.
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IJS, KILJ, NUK, UL, UM, UPUK
PEM fuel cells seem to be the most affordable and commercially viable hydrogen-based cells, the biggest challenge being to obtain CO-free H2 (<100 ppm) as the fuel. In this study, the use of CuO–CeO2 ...catalysts in preferential oxidation of CO to obtain CO-free H2 (PROX reaction) was investigated. Ce1−xCuxO2 catalysts, with x (mol%) = 0, 0.01, 0.03, 0.05 and 0.10, were synthesized in one-step by the polymeric precursor method, to obtain a very fine dispersion and strong metal-support interaction, to favor active copper species and a preference for the PROX reaction. The results obtained from catalyzed reactions and characterization of the catalysts by XRD, Rietveld refinement, BET surface area, UV–Vis and TPR, suggest that this one-step synthesis method gives rise to catalysts with copper species selective for the PROX reaction, which reaches a maximum rate on Ce0.97Cu0.03O2 catalyst.
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► Synthesis of CuO/CeO2 catalysts by the one-step polymeric precursor method. ► 100% CO conversion on Ce0.97Cu0.03O2 catalyst. ► Monomeric surface and dipolar Cu2+ are responsible for the improved CO conversion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
► CdS nanoparticles were synthesized via microwave-assisted solvothermal technique. ► Different morphologies were obtained depending on the solvent used. ► The different solvents influenced on the ...optical properties due to structural defects.
CdS is one of the most important II–VI semiconductors, with applications in solar cells, optoelectronics and electronic devices. CdS nanoparticles were synthesized via microwave-assisted solvothermal technique. Structural and morphological characterization revealed the presence of crystalline structures presenting single phase with different morphologies such as “nanoflowers” and nanoplates depending on the solvent used. Optical characterization was made by diffuse reflectance and photoluminescence spectroscopy, revealing the influence of the different solvents on the optical properties due to structural defects generated during synthesis. It is proposed that these defects are related to sulfur vacancies, with higher concentration of defects for the sample synthesized in ethylene glycol in comparison with the one synthesized in ethylene diamine.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this report we present a systematic structural and magnetic analysis of Co-doped ZnO nanoparticles prepared via a microwave-assisted hydrothermal route. The structural data confirm the ...incorporation of Co ions into the wurtzite ZnO lattice and a Co concentration mainly near/at the surface of the nanoparticles. This Co spatial distribution is set to passivate the surface of the ZnO nanoparticles, inhibiting the nanoparticle growth and suppressing the observation of a ferromagnetic phase. Based on experimental and theoretical results we propose a kinetic-thermodynamic model for the processes of nucleation and growth of the Co-doped ZnO nanoparticles, and attribute the observed ferromagnetic order to a ferromagnetism associated with specific defects and adsorbed elements at the surface of the nanoparticle. Our findings give valuable contribution to the understanding of both the doping process at the nanoscale and the nature of the magnetic properties of the Co-doped ZnO system.
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