Presence Of Gd Research Articles

Amorphous calcium phosphate as a precursor for the synthesis of GdPO4·nH2O nanostructures

In this study, we present a novel dissolution-precipitation approach for the synthesis of rhabdophane-type GdPO4·nH2O nanostructures using amorphous calcium phosphate (ACP) as a precursor. It was shown that in aqueous medium in the presence of Gd3+ ions ACP can be successfully converted to GdPO4·nH2O. We systematically investigated the effects of synthesis duration, P-to-Gd molar ratio in the reaction mixture, synthesis temperature, and hydrothermal reactor filling volume on the phase composition and morphology of the obtained products. The samples were analyzed using powder X-ray diffraction (XRD), thermogravimetry and differential scanning calorimetry (TG-DSC), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Furthermore, the assessment of the specific surface area (SBET) and magnetic properties of the selected samples was performed. The GdPO4·nH2O particles prepared under certain synthesis conditions were characterized by notably high SBET values reaching up to 157 m2g⁻1.

Tailoring scintillation and luminescence through Co-doping engineering: A comparative study of Ce,Tb Co-doped YAGG and GAGG garnet crystals

The development of scintillators with co-doping mechanisms has received significant attention due to the resulting enhancements in luminescence and scintillation properties. Scintillators such as Ce-doped (Gd,Tb)3(Al,Ga)5O12 have been recognized for their improved performance, attributed to the effective energy transfer between Ce3+ and Tb3+ ions. Nevertheless, the presence of Gd3+ introduced complexities, as its absorption lines strongly overlap with those of Tb3+, thus masking the details of mechanisms of the Tb3+↔Ce3+ energy transfer. This study endeavored to elucidate this mechanism by comparing the luminescence characteristics of Ce,Tb co-doped Y3Al2Ga3O12 (YAGG) and Gd3A2Ga3O12 (GAGG) single crystals. Through detailed photoluminescence spectral analysis, it was discerned that GAGG exhibited a more robust Tb3+↔Ce3+ energy transfer, as evidenced by a marked extension in the decay time of Ce3+ luminescence. Furthermore, GAGG demonstrated superior integrated radioluminescence intensity across all compositions which is a result of efficient energy transfer from Gd3+ to the luminescence centers. Additionally, comparative thermally stimulated luminescence glow curves, revealed distinctive spectral features between YAGG and GAGG, underscoring the complexity of their luminescence mechanisms. This comparative study not only augmented our comprehension of the intricate energy transfer processes in Ce, Tb co-doped garnet scintillators but also underscored the potential for tailored scintillator development through strategic ion co-doping.

Revelations of vortex phases and pinning mechanism in GdBa2Cu3O7-δ superconductors: a magneto-electric and magnetization study

Rare earth (RE) and barium (Ba) based cuprate superconductors have garnered considerable attention in both fundamental research and a wide array of engineering and technological applications. Examining the impact of magnetic Gd3+ ions on the GdBa2Cu3O7-δ (GdBCO) system, this study reveals that the presence of Gd3+ ion has tilted the magnetic hysteresis loop, thereby affecting the critical current density (J c ) at low temperatures. Through comprehensive magnetic and magneto-transport data analyses of the GdBCO sample, we have thoroughly explored the intricate behavior of vortices in response to magnetic fields and temperature variations, providing insight into the governing mechanism of vortex pinning. Remarkably, the absolute zero temperature pinning potential (U 0) experiences a significant reduction from a very high value of 3.18 eV to 0.45 eV with a magnetic field increase to 40 KOe, following a H −0.53 law, indicating 3D plastically crippled vortices in weak pinning sites due to point defects. In various technological domains, particularly those involving high temperatures and strong magnetic fields, understanding and optimizing the pinning force (F p ) and the pinning potential (U) of the vortices are pivotal for enhancing performance and efficiency. Consequently, we have meticulously analyzed the nature of F p and U with the aid of the thermally activated flux flow (TAFF) model. Ultimately, we compiled a comprehensive phase diagram delineating the evolution of various vortex phases.

Intermediate conductance Ca2+-activated potassium channels are activated by functional coupling with stretch-activated nonselective cation channels in cricket myocytes.

Cooperative gating of localized ion channels ranges from fine-tuning excitation-contraction coupling in muscle cells to controlling pace-making activity in the heart. Membrane deformation resulting from muscle contraction activates stretch-activated (SA) cation channels. The subsequent Ca2+ influx activates spatially localized Ca2+-sensitive K+ channels to fine-tune spontaneous muscle contraction. To characterize endogenously expressed intermediate conductance Ca2+-activated potassium (IK) channels and assess the functional relevance of the extracellular Ca2+ source leading to IK channel activity, we performed patch-clamp techniques on cricket oviduct myocytes and recorded single-channel data. In this study, we first investigated the identification of IK channels that could be distinguished from endogenously expressed large-conductance Ca2+-activated potassium (BK) channels by adding extracellular Ba2+. The single-channel conductance of the IK channel was 62 pS, and its activity increased with increasing intracellular Ca2+ concentration but was not voltage-dependent. These results indicated that IK channels are endogenously expressed in cricket oviduct myocytes. Second, the Ca2+ influx pathway that activates the IK channel was investigated. The absence of extracellular Ca2+ or the presence of Gd3+ abolished the activity of IK channels. Finally, we investigated the proximity between SA and IK channels. The removal of extracellular Ca2+, administration of Ca2+ to the microscopic region in a pipette, and application of membrane stretching stimulation increased SA channel activity, followed by IK channel activity. Membrane stretch-induced SA and IK channel activity were positively correlated. However, the emergence of IK channel activity and its increase in response to membrane mechanical stretch was not observed without Ca2+ in the pipette. These results strongly suggest that IK channels are endogenously expressed in cricket oviduct myocytes and that IK channel activity is regulated by neighboring SA channel activity. In conclusion, functional coupling between SA and IK channels may underlie the molecular basis of spontaneous rhythmic contractions.

A facile switch-on fluorescence sensing method for detecting phosphates from complex aqueous samples

Phosphates play an essential role in our living systems. Therefore, it is important to have simple and effective methods to detect and monitor the level of phosphates in complex samples. In this study, a facile switch-on fluorescence sensing method is developed for the detection of phosphates. The sensing probes are composed of Gd3+ and riboflavin-5′-phosphate (RFMP), which are hard acid and hard base, respectively. Gd3+ and RFMP can strongly bind via chelation once mixed. RFMP emits bright green fluorescence under ultraviolet (UV) light illumination. However, its fluorescence is quenched in the presence of Gd3+, presumably due to aggregation caused quenching. In the presence of phosphates, the fluorescence derived from RFMP on the Gd3+-RFMP can be restored owing to the competitive binding of phosphates with Gd3+ on the Gd3+-RFMP conjugates to release RFMP. In this study, we demonstrate the feasibility of using the developed sensing method to determine the level of phosphates from real world samples such as drinking water and fetal bovine serum under the illumination of a UV lamp (λmax = 365 nm) simply with the naked eye. The lowest distinguishable concentration of using our detection method towards adenosine triphosphate and pyrophosphate with the naked eye is ∼1 μM. Furthermore, when fluorescence spectroscopy is used as a detection tool, the limit of detection has further reduced to ∼611 nM. The feasibility of using the developed sensing probes combined with fluorescence spectroscopy for quantitative analysis of phosphates in real samples is also demonstrated in this study.

Rare-Earth-Metal (Nd3+, Ce3+ and Gd3+)-Doped CaF2: Nanoparticles for Multimodal Imaging in Biomedical Applications.

Here, we describe the synthesis of a novel type of rare-earth-doped nanoparticles (NPs) for multimodal imaging, by combining the rare-earth elements Ce, Gd and Nd in a crystalline host lattice consisting of CaF2 (CaF2: Ce, Gd, Nd). CaF2: Ce, Gd, Nd NPs are small (15-20 nm), of uniform shape and size distribution, and show good biocompatibility and low immunogenicity in vitro. In addition, CaF2: Ce, Gd, Nd NPs possess excellent optical properties. CaF2: Ce, Gd, Nd NPs produce downconversion emissions in the second near-infrared window (NIR-II, 1000-1700 nm) under 808 nm excitation, with a strong emission peak at 1056 nm. Excitation in the first near- infrared window (NIR-I, 700-900 nm) has the advantage of deeper tissue penetration power and reduced autofluorescence, compared to visible light. Thus, CaF2: Ce, Gd, Nd NPs are ideally suited for in vivo fluorescence imaging. In addition, the presence of Gd3+ makes the NPs intrinsically monitorable by magnetic resonance imaging (MRI). Moreover, next to fluorescence and MR imaging, our results show that CaF2: Ce, Gd, Nd NPs can be used as imaging probes for photoacoustic imaging (PAI) in vitro. Therefore, due to their biocompatibility and suitability as multimodal imaging probes, CaF2: Ce, Gd, Nd NPs exhibit great potential as a traceable imaging agent in biomedical applications.

Enhancement in photovoltaic properties of exciplex quantum dot sensitized solar cells via gadolinium doping and formation of type II Core/Shell (Gd-doped CdS@CdSe) structure

The principal aim behind doping of cadmium sulfide (CdS) quantum dots (QDs) by gadolinium (Gd) cations and fabrication of core (CdS)-shell (cadmium selenide (CdSe)) nanostructures was to increase the performance in the QD-sensitized solar cells (QDSSCs). By simultaneously doping with Gd and designing the core–shell nanostructures, the well-acted photovoltaic cells were fabricated where short current density (Jsc) = 14.91 mA/cm2, fill factor (FF) = 64.9%, open-circuit voltage (Voc) = 707 mV, and power conversion efficiency (η) = 6.84%. The addition of zinc sulfide (ZnS) layer onto TiO2/Gd-doped CdS@CdSe photoanodes improved the cell parameters including Jsc,FF, Voc, and η up to 16.34 mA/cm2, 65.24%, 710 mV, and 7.57%, respectively. The presence of Gd3+ in the the CdS crystal lattice promotes the charge injection rate from the conduction band (CB) of CdS to CB of TiO2 by successive trapping and losing the photoinduced electrons due to its unique half-filled electron configuration in valance f orbitals. Upon creating the Gd3+ doped-CdS@CdSe structures, the exciplex states were formed to reduce the effective bandgap of QDs and expand the light-harvesting range in visible wavelengths. The comparison of relative chemical capacitance (Cμ) under both dark and illumination conditions, obtained from electrochemical impedance spectroscopy (EIS) measurements, revealed that the Gd3+ doping of QDs can shift the CB level of TiO2 and, thereby, elevate the Voc. Moreover, the EIS and photoluminescence (PL) spectroscopy showed that doping suppresses the charge recombination at the photoanode/electrolyte interfaces and also improves Jsc and η in the fabricated cells.

The inhibition of gadolinium ion (Gd3+) on the mitochondrial F1FO-ATPase is linked to the modulation of the mitochondrial permeability transition pore

The mitochondrial permeability transition pore (PTP), which drives regulated cell death when Ca2+ concentration suddenly increases in mitochondria, was related to changes in the Ca2+-activated F1FO-ATPase. The effects of the gadolinium cation (Gd3+), widely used for diagnosis and therapy, and reported as PTP blocker, were evaluated on the F1FO-ATPase activated by Mg2+ or Ca2+ and on the PTP. Gd3+ more effectively inhibits the Ca2+-activated F1FO-ATPase than the Mg2+-activated F1FO-ATPase by a mixed-type inhibition on the former and by uncompetitive mechanism on the latter. Most likely Gd3+ binding to F1, is favoured by Ca2+ insertion. The maximal inactivation rates (kinact) of pseudo-first order inactivation are similar either when the F1FO-ATPase is activated by Ca2+ or by Mg2+. The half-maximal inactivator concentrations (KI) are 2.35 ± 0.35 mM and 0.72 ± 0.11 mM, respectively. The potency of a mechanism-based inhibitor (kinact/KI) also highlights a higher inhibition efficiency of Gd3+ on the Ca2+-activated F1FO-ATPase (0.59 ± 0.09 mM−1∙s−1) than on the Mg2+-activated F1FO-ATPase (0.13 ± 0.02 mM−1∙s−1). Consistently, the PTP is desensitized in presence of Gd3+. The Gd3+ inhibition on both the mitochondrial Ca2+-activated F1FO-ATPase and the PTP strengthens the link between the PTP and the F1FO-ATPase when activated by Ca2+ and provides insights on the biological effects of Gd3+.

The calcium sensing receptor modulates H+-ATPase activity in intercalated cells.

Previous studies found that calcium sensing receptor (CaSR) it's expressed in intercalated cells of the collecting duct and that its activation by calcium in the luminal membrane promotes acidification of urine. Therefore, the aim of the study was to analyze the effects of CaSR stimulus on the biochemical activity of the vacuolar H+-ATPase in a cellular model of intercalated cells, MDCK-C11 cells. Biochemical activity of H+-ATPase was performed using cell homogenates and the inorganic phosphate released was determined by a colorimetric method. Changes in cytosolic ionized calcium ([Ca2+]i) were also determined using Fluo-4. A significant increase of vacuolar H+-ATPase activity was observed when the CaSR was stimulated with agonists such as Gd3+ (300 μM), neomycin (200 μM) and by the calcimimetic R-568 (1 μM). This activity was also stimulated in a dose-dependent fashion by changes in extracellular Ca2+ concentration ([Ca2+]o) between 10-2 and 2 mM. The calciolytic NPS 2143 (150 nM) significantly reduced the vacuolar H+-ATPase activity observed with 2 mM [Ca2+]o. Inhibition of phospholipase C (PLC) activity with U73122 (5 x 10-7 M) reversed the increase in pump activity observed in the presence of Gd3+. Activation of CaSR by the specific CaSR agonist R-568 produced a sustained rise of [Ca2+]i, an effect that disappears when extracellular calcium was removed in the presence of thapsigargin. In summary, CaSR stimulation induces an increase in the vacuolar H+-ATPase activity of MDCK-C11 cells, an effect that involves an increase in [Ca2+]i and require PLC activity. The consequent decrease in intratubular pH could lead to increase ionization of luminal calcium, potentially reducing the formation of calcium phosphate stones.

Effect of Gd3+ ion on the structural and magnetic properties of (Nb and Al) co-doped rutile [formula omitted] single crystal

In this study we investigated the influence of Gd3+ ions on the structural and magnetic properties of (Nb + Al) co-doped TiO2 single crystals with nominal composition Ti0.995(Nb0.667Al0.333)0.005O2 (TNA) and Ti0.995(Nb0.667(Al0.1665Gd0.1665))0.005O2 (TNAGd) grown in an optical traveling floating zone (TFZ) furnace. The crystal structure and phase purity investigated by X-ray diffraction (XRD) and High resolution transmission electron microscopy (HRTEM) images of selected area electron diffraction (SAED) patterns confirmed the rutile crystal nature for both TNA and TNAGd samples. The magnetic properties were studied from 3 to 400 K in magnetic fields up to 60 kOe. ZFC/FC curves revealed paramagnetic behavior for TNA sample, while the presence of Gd3+ ions in the crystal structure drastically affected the magnetic properties turning to ferromagnetic behavior. The isothermal magnetization, M(H) curves for TNAGd samples were analyzed by the bound magnetic polaron (BMP) model. At the lowest temperature the values of the total moment of BMP's (M0), spontaneous moment of a single BMP (ms), and the concentration of BMP's (N) were found to be 1.58emu/cm3, 840 μB, and 3.2×1019BMP/cm3, respectively. The number of Gd3+ ions per BMP was ~113 and 75% of Gd3+ ions were inside the BMP's and the remaining 25% were outside but diluted in the matrix or interacting antiferromagnetically.

Ultraviolet Radiation-Emitting Gd3+-Doped Sr2ZnSi2O7 Host Lattice Prepared by Sol–Gel Procedure and Evaluation of Gamma-Ray Exposure Parameters

Using the sol–gel process, a series of Sr2-xZnSi2O7:xGd (0.01 ≤ x≤0.11) samples was fabricated. Their crystal characteristics, surface morphologies, and spectral characteristics were analyzed using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectroscopy. Upon 272-nm excitation, a prominent emission band appeared at 313 nm (6P7/2 → 8S7/2) in all the samples. The electron paramagnetic resonance (EPR) and PL analyses confirmed the presence of Gd3+ in the Sr2ZnSi2O7 structure, where the Gd3+ ions occupied distorted Sr2+ sites in the host lattice. Additionally, three photon interaction parameters, namely the mass attenuation coefficient, effective atomic number, and effective electron density, were calculated within the 1 keV–100 GeV photon energy range for all the samples. These photon interaction parameters varied widely over the studied energy range. Particularly, the shielding effectiveness increased with increasing gadolinium concentration. These interaction parameters will be very useful for shielding applications against gamma-rays.

Distinct pharmacological profiles of ORAI1, ORAI2, and ORAI3 channels

The ubiquitous Ca2+ release-activated Ca2+ (CRAC) channel is crucial to many physiological functions. Both gain and loss of CRAC function is linked to disease. While ORAI1 is a crucial subunit of CRAC channels, recent evidence suggests that ORAI2 and ORAI3 heteromerize with ORAI1 to form native CRAC channels. Furthermore, ORAI2 and ORAI3 can form CRAC channels independently of ORAI1, suggesting diverse native CRAC stoichiometries. Yet, most available CRAC modifiers are presumed to target ORAI1 with little knowledge of their effects on ORAI2/3 or heteromers of ORAIs. Here, we used ORAI1/2/3 triple-null cells to express individual ORAI1, ORAI2, ORAI3 or ORAI1/2/3 concatemers. We reveal that GSK-7975A and BTP2 essentially abrogate ORAI1 and ORAI2 activity while causing only a partial inhibition of ORAI3. Interestingly, Synta66 abrogated ORAI1 channel function, while potentiating ORAI2 with no effect on ORAI3. CRAC channel activities mediated by concatenated ORAI1-1, ORAI1-2 and ORAI1-3 dimers were inhibited by Synta66, while ORAI2-3 dimers were unaffected. The CRAC enhancer IA65 significantly potentiated ORAI1 and ORAI1-1 activity with marginal effects on other ORAIs. Further, we characterized the profiles of individual ORAI isoforms in the presence of Gd3+ (5μM), 2-APB (5 μM and 50 μM), as well as changes in intracellular and extracellular pH. Our data reveal unique pharmacological features of ORAI isoforms expressed in an ORAI-null background and provide new insights into ORAI isoform selectivity of widely used CRAC pharmacological compounds.

Effect of defects and oxygen vacancies on the RTFM properties of pure and Gd-doped CeO2 nanomaterials through soft XAS

This work primarily is an investigation of the electronic structure properties of pure CeO2 and $${Ce}_{1-x}{Gd}_{x}{O}_{2}$$ (x = 0.02, 0.04, 0.06, 0.08 and 0.10) Nanoparticles using the soft X-ray absorption spectroscopy were used to explore defects and vacancies. For this purpose, pure CeO2 and $${Ce}_{1-x}{Gd}_{x}{O}_{2}$$ (x = 0.02, 0.04, 0.06, 0.08 and 0.10) nanomaterials were synthesized using the co-precipitation method. The XAS spectra at Ce M4,5, O K-edge and Gd M4,5 absorption edges clearly indicated a decrease in the valence state of Ce ions from Ce4+ to Ce3+ with the formation of oxygen vacancy defects upon incorporation of Gd3+ ions in CeO2 nanolattice. The results show meagre and sparse segregations of additive Gd+3 ions to form secondary phases in the samples. The deconvoluted Ce M4,5 peaks and O K-edge peaks clearly showed the existence of both oxidation states of Ce ions, Ce3+ and Ce4+,and also indicated the formation of oxygen vacancy defects in all the samples. The presence of Gd3+ oxidation state of Gd ions in Gd+3-doped CeO2 samples was investigated through Gd M4,5 edges. Furthermore, the origin of ferromagnetism in pure CeO2 and Gd3+-doped CeO2 samples is explained using F-centre exchange mechanism mediated by defects and oxygen vacancies.

Studies on multifunctional properties of GdFe1−xCoxO3 multiferroics

Multiferroics—materials attract considerable attention, due to their fascinating physics properties. The motivating physical properties of GdFe1−xCoxO3 (0.00 ≤ x ≤ 0.25) orthorhombic structure were adjusted in a controlled way by modifying the composition through the synthesis processes. The orthorhombic structure within the space group Pbnm is confirmed through X-ray diffraction patterns. The data reveal that the samples under investigation are G-type antiferromagnetic with a weak ferromagnetic moment. Dzyaloshinskii–Moriya interaction is a crucial source of the observed weak ferromagnetic behavior for the investigated samples. An anisotropy constant for GdFe0.9Co0.1O3 is approximately equal to 4065 emu Oe/gm, which is 9 times greater than that of GdFeO3 samples. The higher values of anisotropic constant K indicate that the prepared samples will be promising and helpful for technological applications at a variety of temperatures. Cobalt doping has a unique advantage as it reduces the switching field distribution and the change of the entropy (ΔS) of the investigated samples. The presence of Gd3+–O2− 2p, Fe3+–O2− 2p and Co–O-2p hybridization stabilizes the ferroelectric distortion causing an improvement in ferroelectric property. The effects of pH value and the contact time on the adsorption progression were studied and optimized to obtain the maximum possible adsorption efficiency of the Gadolinium/cobalt samples. The use of GdFe0.8Co0.2O3 removes 98% of lead from the waste water. The specific advantages of the investigated samples are ease of separation, high adsorption per unit area, low cost as well as recycled with significant efficiency. The investigated samples are recommended to be used as a reusable adsorbent for the highly efficient removal of lead metal ions from aqueous solutions.

The effect of Gd3+ doping on luminescence properties of (Gd, Ce): SrF2 nanopowders and transparent ceramics

The effect of doping of Gd3+ ions into Ce: SrF2 on luminescence properties was investigated in (Gd, Ce): SrF2 nanoparticle powders synthesized via the co-precipitation method, which contained fixed amount of Ce3+ ions and variable amounts of Gd3+ ions. (Gd, Ce): SrF2 nanoparticle powders showed UV range emissions under λex = 273 nm and λex = 298 nm excitation. Photoluminescence emission, excitation, and lifetime measurements revealed the existence of Ce3+ → Gd3+ radiative energy transfer and provided evidence to the prevailing effect of Ce3+ in excitation and emission in the (Gd, Ce) co-doped system due to the existence of fully allowed 4f-5d transitions. The presence of Gd3+ was shown to affect the crystal field and symmetry around Ce3+ ions and enhances the absorption efficiency by two-fold. Furthermore, (Gd, Ce): SrF2 transparent ceramics with 13.2% of in-line optical transmittance in the UV spectral range was obtained via the vacuum hot-pressing method. The increase in the UV luminescence emission intensity of Ce3+ in presence of Gd3+, as well as the ability to process (Gd, Ce): SrF2 as transparent ceramics, are what make (Gd, Ce): SrF2 a promising material for optical applications in the UV region.

Inhibition of Tolaasin Hemolytic Activity by Increase in GD3+-Induced Membrane Rigidity

Tolaasin molecule multimerizes and forms a membrane pore, causing brown blotch disease of the cultivated mushrooms. The peptide is a pore-forming bacterial toxin produced by Pseudomonas tolaasii. The pores destroy plasma membrane by interrupting cellular osmotic pressure. Cytotoxicity of tolaasin can be evaluated by measuring hemolytic activity using erythrocytes and blotch formations on the mushroom tissue. Previous studies showed that divalent cations, such as Zn2+, Ni2+, and Cd2+, inhibit tolaasin-induced hemolysis. In this study, Gadolinium ion, Gd3+, known to inhibit the mechanosensitive ion channels, also inhibits the tolaasin activity as a dose-dependent manner. The inhibition of tolaasin-induced hemolysis was observed at 200 μM Gd3+ and completed at 1 mM. Mechanism of Gd3+ action has not been clearly demonstrated; however, it has been known that Gd3+ decreases membrane fluidity. Inhibition of hemolytic activity by Gd3+ was reversible similar to that of Zn2+, but the action mechanisms of these two ions seem to be very different. Although Zn2+ inhibits the ion channel by plugging into the entrance of tolaasin pore, Gd3+ may inhibit the formation of tolaasin channel by changing membrane fluidity. To investigate the effect of Gd3+ on the plasma membrane of erythrocyte, a fluorescent probe, 1,6-diphenyl-1,3,5-hexatriene (DPH), was inserted into the membrane and the changes in fluorescence intensity were measured. The maximum fluorescence intensity of DPH was measured at 360 nm in excitation and at 456 nm in emission. In the presence of Gd3+, the fluorescence intensity of DPH was increased, suggesting that Gd3+ made the membrane more rigid. Therefore, the Gd3+-mediated increase in membrane rigidity reduces the rate of molecular diffusion in the membrane and may inhibit the multimerization and orientation of tolaasin molecules requiring for membrane pore formation.

Characterization of the cathodoluminescence emission of kamphaugite-(Y) and kristiansenite from Spain

This paper reports on the cathodoluminescence (CL) emission of kamphaugite-(Y) (CaY(CO3)2(OH)·H2O) and kristiansenite [Ca2ScSn(Si2O7)(Si2O6OH)] that display very complex spectra. The carbonate sample, growing in spheres no longer than 3 mm, contains significant concentrations of REE giving rise to sharp and narrow wavebands peaked at 312, 486, 546, 574 and 626 nm. These wavebands would be, respectively, associated with the presence of Gd3+ (6P7/2 → 8S7/2 transition), Dy3+ (4F9/2 → 6H15/2), Tb3+ (5D4 → 7F5), Dy3+ (4F9/2 → 6H13/2) and Sm3+ (4G5/2 → 6H7/2). Kristiansenite, appearing as an isolated pseudo-hexagonal pyramidal crystal smaller than 600 µm, hardly has lanthanide elements and the CL emission is composed of broad wavebands peaked at 298 nm (linked to defect-sites caused by the presence of the Na-0.49%), 334 (due to oxygen vacancies and Me–O bonding defects), 422 (–O–O– type defects and/or O2− intrinsic defects), 494 (self-trapped excitons), 578 [Mn2+ giving rise to 4T2(G) → 6A1(S) transition and/or Ti4+/Sn4+ redox reactions] and 654 nm [due to Fe3+ 4T1(G) → 6A1(S) transitions].

Influence Blocking by Gadolinium in Calcium Diffusion on Synapse Model: A Monte Carlo Simulation Study.

Background: Gadolinium (Gd3+) is a chemical element belonging to the lanthanide group and commonly used in magnetic resonance imaging (MRI) as a contrast agent. However, recently, gadolinium has been reported deposition in the body after a patient receives multiple injections. Gadolinium is a potent block and competes with calcium diffusion into the presynaptic. There has not been a precise mechanism of gadolinium blocking calcium channel as a channel of calcium diffusion to presynaptic until now.Objective: This study aims to investigate the mechanism of calcium influx model and the effect of neurotransmitter release to the synaptic cleft influenced by the presence of Gd3+. Material and Methods: Monte Carlo Cell simulation was used to analyze simulation and also Blender was used to create and visualize the model for synapse. The synapse modeled by a form resembling the actual synapse base on a spherical shape.Results: The presence of gadolinium around the presynaptic has been disturbing diffusion of calcium influx presynaptic. The result shows that the presence of gadolinium around the presynaptic has caused a decrease in the amount of calcium influx presynaptic. These factors contribute to reducing the establishment of the active membrane, then the amount of synaptic vesicle docking and finally the amount of released neurotransmitter.Conclusion: Gadolinium and calcium compete with each other across of calcium channel. The presence of gadolinium has caused a chain effect for signal transmission at the chemical synapse, reducing the amount of active membrane, synaptic vesicle docking, and releasing neurotransmitter.

Synthesis and characterization of Gd3+- and Tb3+-doped iron oxide nanoparticles for possible endoradiotherapy and hyperthermia

Abstract A large range of nanoscale superparamagnetic materials has been under scrutiny from the point of view of their potential theranostic, multimodal applications. In this paper we have investigated the effect of replacing Fe3+ cations with Gd3+ and Tb3+ in the core of the superparamagnetic iron oxide nanoparticles in search for the optimum level of magnetic core doping with these lanthanides. We have found that the presence of Gd3+ and Tb3+ up to 2.5% at. does not alter significantly the crystallographic structure of such nanoferrites and does not compromise the magnetic properties of doped nanoparticles. The doping level, though relatively small, exceeds the levels of currently used radiopharmaceuticals, where only few radionuclides can be incorporated in a single radiotherapeutic molecule. This new type of multifunctional nanoparticles can be used not only as drug carriers or in magnetic hyperthermia, but also in the so-called endoradiotherapy. The latter feature can be easily implemented upon the replacement of “cold” ions of Tb3+ and Gd3+ in the superparamagnetic core with their isotopes emitting soft β− radiation suitable for the internal radiotherapy, localized directly within the tumor. Therefore, these nanoparticles can be used simultaneously in targeted drug delivery, hyperthermia and radiotherapy.

Scaffold-free, label-free and nozzle-free biofabrication technology using magnetic levitational assembly

Tissue spheroids have been proposed as building blocks in 3D biofabrication. Conventional magnetic force-driven 2D patterning of tissue spheroids requires prior cell labeling by magnetic nanoparticles, meanwhile a label-free approach for 3D magnetic levitational assembly has been introduced. Here we present first time report on rapid assembly of 3D tissue construct using scaffold-free, nozzle-free and label-free magnetic levitation of tissue spheroids. Chondrospheres of standard size, shape and capable to fusion have been biofabricated from primary sheep chondrocytes using non-adhesive technology. Label-free magnetic levitation was performed using a prototype device equipped with permanent magnets in presence of gadolinium (Gd3+) in culture media, which enables magnetic levitation. Mathematical modeling and computer simulations were used for prediction of magnetic field and kinetics of tissue spheroids assembly into 3D tissue constructs. First, we used polystyrene beads to simulate the assembly of tissue spheroids and to determine the optimal settings for magnetic levitation in presence of Gd3+. Second, we proved the ability of chondrospheres to assemble rapidly into 3D tissue construct in the permanent magnetic field in the presence of Gd3+. Thus, scaffold- and label-free magnetic levitation of tissue spheroids is a promising approach for rapid 3D biofabrication and attractive alternative to label-based magnetic force-driven tissue engineering.