Structural characterization of interfaces in silica core-alumina shell microspheres by solid-state NMR spectroscopy.

Atomic-scale description of surfaces and interfaces in core-shell aluminosilicate materials is not fully elucidated, partially due to their amorphous character and complex mechanisms that govern their properties. In this paper, new insights into nanostructured core-shell aluminosilicates have been demonstrated, by using different solid-state NMR methods, i.e 29Si, 29Si cross-polarization (CP), 27Al, 27Al triple-quantum (3Q), and 1H-27Al heteronuclear correlation (HETCOR) MAS NMR. For this purpose, nanostructured silica core-alumina shell microspheres, undoped and doped with gadolinium ions respectively, obtained by a chemical synthesis based on the Stöber method for the silica core and electrostatic attraction for developing the alumina shell were studied. As a result, a new alumino-silicate layer formation was proved at the interface between silica core, where aluminum diffuses, on small scale, in the silica network, and alumina shell, where silicon ions migrate, on a larger scale, in the alumina network, leading to a stable core-shell structure. Moreover, this process is accompanied by significant local structural changes in the transition zone, particularly at the aluminum neighborhood, which is quite well understood now, with the power of solid-state NMR spectroscopy.

Potential clinical benefits and limitations of fetal virtopsy using high-field MRI at 7 Tesla versus stereomicroscopic autopsy to assess first trimester fetuses.

OBJECTIVE: The aim of this study was to establish the diagnostic accuracy of high-field magnetic resonance imaging (MRI) at 7 Tesla (T) compared with that of stereomicroscopic autopsy for assessing first trimester fetuses. METHODS: Nine consecutive cases of first trimester fetuses resulting from spontaneous and therapeutic pregnancy termination were considered. The cases were divided into two groups according to gestational age: the Embryo Group with cases of nine to 10 gestational weeks (GWs) and the Fetus Group with cases of 13 GWs. The first group was scanned using three-dimensional fast imaging with steady state precession (3D FISP), and the second group was scanned using a two-dimensional (2D) turbo spin-echo high-resolution T2-weighted imaging (T2 WI) protocol. A radiologist and two embryologists interpreted the images. All cases were evaluated by invasive autopsy, with pathologist blinded to the imaging results. In total, the database included 270 items for evaluation (9 cases × 30 structures/case). RESULTS: The global agreement between fetal high-field virtopsy and microscopic or stereomicroscopic autopsy was evaluated using 225 evaluation items visible by both methods. Overall, using microscopic examination and stereomicroscopic autopsy as the gold standard, fetal high-field virtopsy had a sensitivity of 94.6% [95% CI, 87.2-98.3] and a specificity of 97.6% [95% CI, 95-98.8]. The positive predictive value (PPV) was 93% [95% CI, 85.7-96.6], and the negative predictive value (NPV) was 98.2% [95% CI, 95.7-99.4]. Cohen kappa coefficient of agreement was k = 0.92 [95% CI, 0.82-0.97], and the McNemar test showed p = 1.00. CONCLUSIONS: Virtual autopsy using high-field MRI at 7 T can be considered a safe alternative approach to stereomicroscopic autopsy for the assessment of fetal structural anomalies at the end of the first trimester of pregnancy.

Conformational Changes and Competitive Adsorption between Serum Albumin and Hemoglobin on Bioceramic Substrates.

Traditional methods to analyze interactions and conformational changes of proteins adsorbed onto biomaterials are limited by the protein's associations with the substrate material and the complexity of the surrounding media. We have used EPR spectroscopy in combination with site-directed spin labeling (SDSL) to investigate single protein and competitive adsorption kinetics of horse hemoglobin (Hgb) and bovine serum albumin (BSA) on a silica-calcium-phosphate bioceramic substrate. Combined continuous wave and pulsed (DEER) EPR techniques were employed to monitor local mobility/flexibility changes within the proteins and tertiary structure dynamics upon adsorption. An alternate labeling technique was introduced to allow for specific quantification of each protein adsorbed to the bioceramic surface. We show that at buffer pH 7.4 and 4.7 the amount of adsorbed hemoglobin was increased by a factor of 4-5 compared with BSA. The tertiary structure of hemoglobin was strongly affected upon adsorption, leading to a dissociation of the tetrameric molecule into monomers or αß dimers. When the bioceramic substrate was previously functionalized with a layer of BSA, dissociation was reduced by 71 % compared with the untreated surface, indicating a "primer" effect of BSA for better adhesion of the globular hemoglobin.

Dental follicle stem cells in bone regeneration on titanium implants.

BACKGROUND: We aimed to demonstrate that DF stem cells from impacted molars and canines can be used to improve bone regeneration on titanium implants surfaces. This study highlights the presence of stem cells in DF, their potential to adhere and differentiate into osteoblasts on different types of titanium surfaces. RESULTS: Isolated cells from the harvested DF tissue from impacted canine/molars, expressed stem cells markers. Differentiation into bone cells was induced in presence or absence of BMP-2 and TGFß1. The presence of growth factors until 28 days in medium maintained the cells in an earlier stage of differentiation with a lower level of specific bone proteins and a higher expression of alkaline phosphatase (ALP). Influence of titanium implants with different bioactive coatings, hydroxyapatite (TiHA) and with silicatitanate (TiSiO2), and porous Ti6Al7Nb implants as control (TiCtrl), was studied in terms of cell adhesion and viability. Ti HA implants proved to be more favorable for adhesion and proliferation of DF stem cells in first days of cultivation. The influence of titanium coatings and osteogenic differentiation mediums with or without growth factors were evaluated. Additional BMP-2 in the medium did not allow DF stem cells to develop a more mature phenotype, leaving them in a pre-osteogenic stage. The best sustained mineralization process evaluated by immuno-cytochemical staining, scanning electron microscopy and Ca(2+) quantification was observed for TiHA implants with a higher expression of ALP, collagen and Ca(2+) deposition. Long term culturing (70 days) on titanium surfaces of DF stem cells in standard medium without soluble osteogenic inducers, indicated that HA coating is more favorable, with the acquisition of a more mature osteoblastic phenotype as shown by immunocytochemical staining. These findings demonstrated that even in absence of exogenous osteogenic factors, TiHA implants and in a lesser extent TiCtrl and TiSiO2 implants can induce and sustain osteogenic differentiation of DF stem cells, by their chemical and topographical properties. CONCLUSIONS: Our research demonstrated that DF stem cells have a spontaneous tendency for osteogenic differentiation and can be used for improving bone regeneration on titanium implants surfaces.

Mechanochemical Synthesis of New Praziquantel Cocrystals: Solid-State Characterization and Solubility.

New cocrystals of praziquantel with suberic, 3-hydroxybenzoic, benzene-1,2,4,5-tetracarboxylic, trimesic, and 5-hydroxyisophthalic acids were obtained through ball milling experiments. The optimal conditions for the milling process were chosen by changing the solvent volume and the mechanical action time. Supramolecular interactions in the new cocrystals are detailed based on single-crystal X-ray diffraction analysis, confirming the expected formation of hydrogen bonds between the praziquantel carbonyl group and the carboxyl (or hydroxyl) moieties of the coformers. Different structural characterization techniques were performed for all samples, but the praziquantel:suberic acid cocrystal includes a wider range of investigations such as thermal analysis, infrared and X-ray photoelectron spectroscopies, and SEM microscopy. The stability for up to five months was established by keeping it under extreme conditions of temperature and humidity. Solubility studies were carried out for all the new forms disclosed herein and compared with the promising cocrystals previously reported with salicylic, 4-aminosalicylic, vanillic, and oxalic acids. HPLC analyses revealed a higher solubility for most of the new cocrystal forms, as compared to pure praziquantel.

Co-Crystals of Etravirine by Mechanochemical Activation.

The co-crystals formation of etravirine with three carboxylic acids was investigated. New co-crystals of etravirine with adipic acid, benzoic acid, and 4-hydroxybenzoic acid have been synthesized by wet milling of ingredients for 120 min. The novelty of these solid forms was first evidenced by powder X-ray diffraction. Their different morphology was evidenced by SEM microscopy. Spectroscopic analyses (FT-IR, MAS-NMR, and XPS) highlighted the hydrogen bonds between etravirine and co-formers, as a result of the solid-state reaction of the ingredients by wet milling. Thermal analyses pointed out that the milling process caused in co-crystals a reduction in the fusion enthalpy and the melting temperature, compared to the values obtained for etravirine. These co-crystals are stable up to four months on storage under extreme conditions, excepting the co-crystal with benzoic acid which begins to transform into a polymorph of etravirine after 30 days. The UV absorption spectra of the samples tested in three simulated physiological media with pH values of 6, 6.3, and 7 have evidenced the conformation change of etravirine due to hydrogen bonds between etravirine and carboxylic acids.

The Evaluation of the Four-Chamber Cardiac Dissection Method of the Fetal Heart as an Alternative to Conventional Inflow-Outflow Dissection in Small Gestational-Age Fetuses.

The examination of very small fetal hearts requires special equipment and a specialist that are not available in many general pathology laboratories. Compared to conventional examination, the four-chamber cardiac dissection (4CCD) method can be performed by any pathologist using instruments generally available in pathology services. The aim of this study is to evaluate the efficiency of the 4CCD method in the examination of small fetal hearts using post-mortem magnetic resonance imaging (pm-MRI) at 7T as the standard. Twelve fetuses with gestational ages between 13 and 19 weeks have been included in this study. All fetuses underwent pm-MRI examination prior to pathologic examination. The 4CCD method was used for the cardiac examination in all cases following the same guidelines for cardiac sectioning. The 4CCD was able to identify all cardiac anatomic structures as compared to pm-MRI at 7T, demonstrating a sensibility of 95.8% (95% CI, 94.5-95.8) and specificity of 100% (95% CI, 32.3-100). The overall accuracy in identifying cardiac anatomic structures was 95.8% (95% CI, 93.4-95.8). Additionally, the 4CCD method was able to detect cardiac anomalies with an overall diagnostic accuracy of 91% (95% CI, 85.8-94.2), sensibility of 67.6% (95% CI, 54.5-75.3), and specificity of 97% (95% CI, 93.7-99) as compared to pm-MRI at 7T. The four-chamber view dissection method can be considered as an alternative to the conventional inflow-outflow dissection method in selected cases.

Toxicity assessment of industrial engineered and airborne process-generated nanoparticles in a 3D human airway epithelial in vitro model.

The advanced ceramic technology has been pointed out as a potentially relevant case of occupational exposure to nanoparticles (NP). Not only when nanoscale powders are being used for production, but also in the high-temperature processing of ceramic materials there is also a high potential for NP release into the workplace environment. In vitro toxicity of engineered NP (ENP) [antimony tin oxide (Sb2O3•SnO2; ATO); zirconium oxide (ZrO2)], as well as process-generated NP (PGNP), and fine particles (PGFP), was assessed in MucilAir™ cultures at air-liquid interface (ALI). Cultures were exposed during three consecutive days to varying doses of the aerosolized NP. General cytotoxicity [lactate dehydrogenase (LDH) release, WST-1 metabolization], (oxidative) DNA damage, and the levels of pro-inflammatory mediators (IL-8 and MCP-1) were assessed. Data revealed that ENP (5.56 µg ATO/cm2 and 10.98 µg ZrO2/cm2) only caused mild cytotoxicity at early timepoints (24 h), whereas cells seemed to recover quickly since no significant changes in cytotoxicity were observed at late timepoints (72 h). No meaningful effects of the ENP were observed regarding DNA damage and cytokine levels. PGFP affected cell viability at dose levels as low as ∼9 µg/cm2, which was not seen for PGNP. However, exposure to PGNP (∼4.5 µg/cm2) caused an increase in oxidative DNA damage. These results indicated that PGFP and PGNP exhibit higher toxicity potential than ENP in mass per area unit. However, the presence of a mucociliary apparatus, as it occurs in vivo as a defense mechanism, seems to considerably attenuate the observed toxic effects. Our findings highlight the potential hazard associated with exposure to incidental NP in industrial settings.

In Vitro Toxicity of Industrially Relevant Engineered Nanoparticles in Human Alveolar Epithelial Cells: Air-Liquid Interface versus Submerged Cultures.

Diverse industries have already incorporated within their production processes engineered nanoparticles (ENP), increasing the potential risk of worker inhalation exposure. In vitro models have been widely used to investigate ENP toxicity. Air-liquid interface (ALI) cell cultures have been emerging as a valuable alternative to submerged cultures as they are more representative of the inhalation exposure to airborne nano-sized particles. We compared the in vitro toxicity of four ENP used as raw materials in the advanced ceramics sector in human alveolar epithelial-like cells cultured under submerged or ALI conditions. Submerged cultures were exposed to ENP liquid suspensions or to aerosolised ENP at ALI. Toxicity was assessed by determining LDH release, WST-1 metabolisation and DNA damage. Overall, cells were more sensitive to ENP cytotoxic effects when cultured and exposed under ALI. No significant cytotoxicity was observed after 24 h exposure to ENP liquid suspensions, although aerosolised ENP clearly affected cell viability and LDH release. In general, all ENP increased primary DNA damage regardless of the exposure mode, where an increase in DNA strand-breaks was only detected under submerged conditions. Our data show that at relevant occupational concentrations, the selected ENP exert mild toxicity to alveolar epithelial cells and exposure at ALI might be the most suitable choice when assessing ENP toxicity in respiratory models under realistic exposure conditions.

Bone regeneration response in an experimental long bone defect orthotopically implanted with alginate-pullulan-glass-ceramic composite scaffolds.

In the present study, scaffolds based on alginate-pullulan-bioactive glass-ceramic with 0.5 and 1.5 mol % copper oxide were orthotopically implanted in experimental rat models to assess their ability to heal an induced bone defect. By implying magnetic resonance and imaging scans together with histological evaluation of the processed samples, a progressive healing of bone was observed within 5 weeks. Furthermore, as the regenerative process continued, new bone tissue was formed, enhancing the growth of irregular bone spicules around the scaffolds. A significantly higher amount of new bone was formed (37%) in the defect that received the composite with 1.5 mol % CuO (in glass-ceramic matrix) content implant. Nevertheless, the bone regeneration obtained by scaffold with 0.5 mol % CuO implanted is comparable with the alginate-pullulan-ß-tricalcium phosphate/hydroxiapatite composite implant. The assessed amount of new bone formed was found to be between 29.75 and 37.15% for all the composition involved in the present study. During this process a regeneration process was shown when the alginate-pullulan composite materials were involved, fact that indicate the great potential of these materials to be used in tissue engineering.

Structural changes of piezoelectric La3Ga5SiO14 induced by paramagnetic ions revealed by 71Ga multiple quantum magic angle spinning.

Experimental evidence that nuclear magnetic resonance (NMR) can detect structural changes of piezoelectric La(3)Ga(5)SiO(14) induced by dilute paramagnetic ions is presented. Gd(3+) and Eu(3+) cations have been incorporated into La(3)Ga(5)SiO(14) monocrystals. As expected, the line-width of the tetrahedral (29)Si magic angle spinning (MAS) NMR spectra as well as the inverse of the T(2) relaxation time of (71)Ga increases with the concentration of the paramagnetic ions. A surprising result is shown by (71)Ga multiple quantum (MQ) MAS NMR spectrum, which changes with the concentration of paramagnetic ions. The changes in the (71)Ga MQMAS spectra can be explained by a more ordonated distribution of Ga ions inside the oxygen tetrahedra. The (71)Ga MQMAS NMR spectra allow identification of the one octahedral and two tetrahedral Ga sites.

Bioactivity evolution of the surface functionalized bioactive glasses.

The formation of a calcium phosphate layer on the surface of the SiO2 -CaO-P2 O5 glasses after immersion in simulated body fluid (SBF) generally demonstrates the bioactivity of these materials. Grafting of the surface by chemical bonding can minimize the structural changes in protein adsorbed on the surface. Therefore, in this study our interest was to evaluate the bioactivity and blood biocompatibility of the SiO2 -CaO-P2 O5 glasses after their surface modification by functionalization with aminopropyl-triethoxysilane and/or by fibrinogen. It is shown that the fibrinogen adsorbed on the glass surfaces induces a growing of the apatite-like layer. It is also evidenced that the protein content from SBF influences the growth of the apatite-like layer. Furthermore, the good blood compatibility of the materials after fibrinogen and bovine serum albumin adsorption is proved from the assessment of the ß-sheet-ß-turn ratio.

Note: sensitivity multiplication module for quartz crystal microbalance applications.

In this Note, a novel sensitivity multiplication module was added to classical quartz crystal microbalance (QCM). The purpose is to increase QCM frequency shift without changing nominal frequency of the quartz crystal resonator or nominal frequency value delivered to the frequency counter. Allan deviance measurement confirms that the multiplication of the frequency shift is limited by the quartz crystal loads with direct effect in quartz crystal quality factor and oscillator stability. An experimental implementation of this new sensitivity multiplication module that can increase up to six times the frequency shift of the QCM was experimentally investigated using different load conditions.

Molybdenum effect on the structure of SiO2-CaO-P2O5 bioactive xerogels and on their interface processes with simulated biofluids.

The study is focused on synthesis, investigation of the structural and morphological changes induced by MoO3 addition, and thermal treatment, as well as in vitro characterization of a new sol-gel derived SiO2-CaO-P2O5 bioactive materials. The obtained systems are composite materials consisting of nanocrystalline apatite, bioactive glass and CaMoO4 nanoparticles, which are of interest for both regenerative medicine and specific medical applications of the releasable molybdenum ions. The changes induced by the thermal treatments and MoO3 addition with respect to the structure and morphology were completed using differential thermal analysis\thermogravimetric analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, electron paramagnetic resonance, and Brunauer-Emmett-Teller. The biological performance of these materials was evaluated in vitro by performing bioactivity and biocompatibility tests. The bioactive properties in terms of hydroxyapatite layer formation on the biomaterial surface after simulated body fluid immersion were studied by XRD and SEM. To establish their biocompatibility, the biomaterials surface was functionalized with protein and the resulted sample was investigated using SEM, FTIR, and XPS. The obtained results suggest that the addition of molybdenum oxide in proper concentration improves the biocompatibility in terms of enhancement of protein adherence on Si-Ca-P surface due to CaMoO4 crystalline phase development and does not inhibit bioactivity.

Comparative in vitro study regarding the biocompatibility of titanium-base composites infiltrated with hydroxyapatite or silicatitanate.

BACKGROUND: The development of novel biomaterials able to control cell activities and direct their fate is warranted for engineering functional bone tissues. Adding bioactive materials can improve new bone formation and better osseointegration. Three types of titanium (Ti) implants were tested for in vitro biocompatibility in this comparative study: Ti6Al7Nb implants with 25% total porosity used as controls, implants infiltrated using a sol-gel method with hydroxyapatite (Ti HA) and silicatitanate (Ti SiO2). The behavior of human osteoblasts was observed in terms of adhesion, cell growth and differentiation. RESULTS: The two coating methods have provided different morphological and chemical properties (SEM and EDX analysis). Cell attachment in the first hour was slower on the Ti HA scaffolds when compared to Ti SiO2 and porous uncoated Ti implants. The Alamar blue test and the assessment of total protein content uncovered a peak of metabolic activity at day 8-9 with an advantage for Ti SiO2 implants. Osteoblast differentiation and de novo mineralization, evaluated by osteopontin (OP) expression (ELISA and immnocytochemistry), alkaline phosphatase (ALP) activity, calcium deposition (alizarin red), collagen synthesis (SIRCOL test and immnocytochemical staining) and osteocalcin (OC) expression, highlighted the higher osteoconductive ability of Ti HA implants. Higher soluble collagen levels were found for cells cultured in simple osteogenic differentiation medium on control Ti and Ti SiO2 implants. Osteocalcin (OC), a marker of terminal osteoblastic differentiation, was most strongly expressed in osteoblasts cultivated on Ti SiO2 implants. CONCLUSIONS: The behavior of osteoblasts depends on the type of implant and culture conditions. Ti SiO2 scaffolds sustain osteoblast adhesion and promote differentiation with increased collagen and non-collagenic proteins (OP and OC) production. Ti HA implants have a lower ability to induce cell adhesion and proliferation but an increased capacity to induce early mineralization. Addition of growth factors BMP-2 and TGFß1 in differentiation medium did not improve the mineralization process. Both types of infiltrates have their advantages and limitations, which can be exploited depending on local conditions of bone lesions that have to be repaired. These limitations can also be offset through methods of functionalization with biomolecules involved in osteogenesis.