Role Of Gd3 Research Articles

Role of Gd3+ ions in alumino borosilicate glasses studied through structural, optical and thermoluminescence characteristics for gamma dosimetry applications

This paper reports the structural, optical and thermoluminescence properties of Gd3+ ions incorporated alumino-borosilicate glasses, prepared through the melt-quench technique. The amorphous nature of the glasses is confirmed through XRD study. Network vibrations of borate and silicate groups, vibrations of hydrogen bonding and hydroxyl groups are realized via FTIR study. The Gd3+ transition peaks are absent in the near ultraviolet, visible and NIR regions, and the indirect bandgap values were determined through UV–Visible–NIR study. Photoluminescence measurements showed a concentration quenching in the glasses beyond 1.5 mol % of Gd3+ ions. Based on the thermoluminescence (TL) data, the 2 mol % of Gd2O3 doped glass (BSGD5) was chosen as optimum sample because of the presence of maximum TL intensity. The BSGD5 glass displayed TL response linearity in 0.25–1 kGy dose region giving a high signal sensitivity of 220,068 counts. g−1 kGy−1 in this region. With nearer tissue equivalence and a minimum detectable dose of 0.02 Gy, the suitability of BSGD5 glass for gamma dosimetry application was deducted. Electron spin resonance (ESR) study validated the presence of intrinsic defects in Gd3+ glasses which are responsible for changes in the intensity and shape of TL glow curves. Hence, from the obtained results Gd3+ doped alumino borosilicate glasses can be considered as potential candidates for gamma dosimetry application.

On the role of Gd3+ ions in enhancement of UV emission from Yb3+–Tm3+ up-converting LiYF4 nanocrystals

Materials capable of emitting ultraviolet (UV) radiation are sought for applications ranging from theranostics or photodynamic therapy to specific photocatalysis. The nanometer size of these materials, as well as excitation with near-infrared (NIR) light, is essential for many applications. Tetragonal tetrafluoride LiY(Gd)F4 nanocrystalline host for up-converting Tm3+–Yb3+ activator-sensitizer pair is a promising candidate to achieve UV–vis up-converted radiation under NIR excitation, important for numerous photo-chemical and bio-medical applications. Here, we provide insights into the structure, morphology, size and optical properties of up-converting LiYF4:25%Yb3+0.5%Tm3+ colloidal nanocrystals, where 1, 5, 10, 20, 30 and 40% of Y3+ ions were substituted with Gd3+ ions. Low gadolinium dopant concentrations modify the size and up-conversion luminescence, while the Gd3+ doping that is exceeding the structure resistance limit of the tetragonal LiYF4 results in appearance of foreign phase and significant decrease of luminescence intensity. The intensity and kinetic behavior of Gd3+ up-converted UV emission are also analyzed for various gadolinium ions concentrations. The obtained results form a background for further optimized materials and applications based on LiYF4 nanocrystals.

Role of Gd3+ and Ho3+ doping on the structure, physical properties and applications of ZnO

ZnO, Zn0.97Gd0.03O and Zn0.97Ho0.03O were prepared via a citrate auto-combustion method. X-ray diffraction (XRD) demonstrated that the investigated nanoparticles were prepared in a hexagonal structure, with crystallite sizes averaging between 12 and 60 nm. The morphology of the samples is illustrated by the field emission scanning electron microscope (FESEM) images. The paramagnetic behavior of the investigated nanoparticles is demonstrated by VSM. The value of the optical band gap (Eg) of Zn0.97Gd0.03O was higher than the Eg of ZnO due to the Moss–Burstein effect. Heavy metal Cd2+ ions from water are effectively adsorbed by rare earth-doped ZnO. At pH = 8, Zn0.97Ho0.03O exhibits a maximum removal efficiency of 91%. The Freundlich isotherm model fits the experimental results well.

Role of Gd3+ on the magnetocaloric properties of lanthanum-strontium manganite

In this work, the role of magnetic ion Gd3+ in the crystal structure, magnetic and magnetocaloric properties of doped lanthanum-strontium manganite (La0.7-xGdxSr0.3MnO3 varying x from 0 to 0.2) synthesized by high-energy ball milling assisted with annealing, is discussed. Furthermore, the interplay between the magnetic and crystal structure in co-doped manganites is proposed. The X-ray diffraction patterns confirm the complete formation of lanthanum manganite showing different crystal structures regarding the gadolinium content. The Sr2+/Gd3+ doped lanthanum manganites with Gd3+ concentration lower than 0.1 mol show rhombohedral crystal structure (R-3cH). Higher gadolinium concentrations promote a phase transition from rhombohedral to orthorhombic crystal structure. The Curie temperature of the manganites decreases with an increase in Gd3+ content, from 376 K to 257 K, for un-doped and x = 0.2 Gd3+, respectively, attributed to a weakening in the double exchange interaction. Close interaction of the lattice parameters such as bond distances, bond angles, and symmetry-related with the mixed magnetic interactions was observed. The maximum magnetocaloric effect (MCE) calculated using Maxwelĺs ratio was observed around the paramagnetic to ferromagnetic ordering, at 311 K, for gadolinium content of 0.15 mol, measured through the entropy change. The Sr2+/Gd3+ doped lanthanum manganite shows a magnetically induced entropy change (|ΔSM|) in the range from 2.4 to 3.69 Jkg-1K−1 under 18 kOe, for 0.10 and 0.15, respectively, doing this manganite a suitable material for refrigeration applications at room temperature.

Gangliosides in nervous system development, regeneration, and pathologies

Gangliosides, sialic acid-containing sphingolipids, are major constituents of neuronal membranes. According to the number of sialic acids and the structure of the oligosaccharide chain, gangliosides can be classified as simple or complex and grouped in different ganglio-series. Hundreds of gangliosides have been identified in vertebrate cells, with different expression patterns during development and related to several physiological processes, especially in the nervous system. While GD3 and its O-acetylated form, 9acGD3, are highly expressed in early developmental stages, GM1, GD1a, GD1b, and GT1b are the most abundant ganglioside species in the mature nervous system. Mutations in enzymes involved in ganglioside metabolism can lead to the accumulation of specific species, a condition termed gangliosidosis and usually marked by severe neurological impairment. Changes in ganglioside levels have also been described in several neurodegenerative diseases, such as Alzheimer’s and Parkinson’s. In this review, we summarized recent information about the roles of GD3, 9acGD3, GM1, GD1a, GD1b, GT1b, and other ganglioside species in nervous system development and regeneration, as well as clinical trials evaluating possible therapeutic applications of these molecules.

Photoluminescence and X-Ray Induced Scintillation: The Role of Gd3+ to Ce3+ Energy Transfer in Fluorophosphate Glasses

Photoluminescence and X-Ray Induced Scintillation: The Role of Gd3+ to Ce3+ Energy Transfer in Fluorophosphate Glasses

Gadolinium chloride promotes proliferation of HEK293 human embryonic kidney cells by activating EGFR/PI3K/Akt and MAPK pathways.

Prolonged exposure to gadolinium-based contrast agents has been reported to trigger nephrogenic systemic fibrosis in end stage renal disease patients. However, the exact molecular mechanisms are not fully understood, and no effective therapy is available to date. In the present study, we report that gadolinium chloride (Gd3+) concentration- and time-dependently promoted the proliferation of HEK293 human embryonic kidney cells by increasing DNA synthesis. Gd3+ treatment increased the protein levels of phosphorylated Akt and MAPKs. Inhibition of Akt and ERK by pharmacological inhibitors abolished the increased proliferation and cell cycle progression. Furthermore, Gd3+ activated EGFR signaling possibly by enhancing EGFR clustering on the cell membrane. Inhibition of EGFR by gefitinib blocked Gd3+-induced proliferation. Gd3+ exposure also upregulated the mRNA levels of TGFβ-1, TGFβR1, TNFα, TIMP-1 and integrin αV, β1 which could also be attenuated by the inhibition of Akt and ERK signaling. Our study provides new clues for the etiological role of Gd3+ in the pathogenesis of nephrogenic systemic fibrosis, and suggests the inhibition of EGFR/Akt/ERK signaling as a potential treatment strategy.

Diffusion and Interaction between ion Ca2+ and ion Gd3+ in a Model Synapse: A Monte Carlo Study

Gadolinium (Gd3+) is a commonly used in MRI. The role of Gd3+ as contrast agent greatly helps to improve the quality of an image and Gadolinium entrance in a body through a diffusion process after administration. Diffusion process takes place from outside pre-synapse to inside pre-synapse through Ca2+ channels. This process causes a delay of Ca2+ in passing Ca2+ channels to pre-synapse. This study aims to determine equilibrium concentration of Ca2+ and Gd3+ so that Ca2+ can pass Ca2+ channels. To address the effect of Gd3+ concentration around Ca2+ channels, we developed a Monte Carlo simulation on Ca diffusion and interaction with Gd. We find Gd3+ concentration in a certain threshold can be potential as a blocker Ca2+ diffuse entrance into pre-synapse. In another hand, an amount of Ca2+ channels and pre-synapse terminal to continuing diffusion of vesicles to clef was important. And the trapping Gd3+ in pre-synapse effects in diffusion delays also. These simulations identify characteristics of the interaction between Ca2+ and Gd3+ in Ca channels which entrance into pre-synapse through diffusion process depend on concentration with each other.

Tuning the electronic and structural properties of Gd-TiO2-GO nanocomposites for enhancing photodegradation of IC dye: The role of Gd3+ ion

In recent years, there has been a growing interest in developing highly efficient photocatalysts with a visible light active semiconductor as one of its components. Herein, visible-light-driven photocatalytic activity of Gd-TiO2-GO nanocomposites were fabricated by sol–gel method. The photocatalytic property was evaluated for photodegradation of indigo carmine (IC) dye. The structural properties of the fabricated samples were characterised using SEM, XRD, PL, TEM, Raman, BET, EDS, elemental mapping and XPS analysis. To provide further insights into the synergistic effect, a hybrid density functional theory calculation was used to study the charge transfer, electronic and structural properties of Gd–TiO2–GO nanocomposite. The as-fabricated nanocomposites showed improved visible light photocatalytic performance and degradation efficiency over pure TiO2. The optimal Gd content was found to be 0.6 wt%, and the apparent pseudo-first order photodegradation rate of IC dye was 14.19-fold higher than that of pure TiO2 nanoparticles under visible–light irradiation. Moreover, hydroxide radicals and holes were the main active species, and the hybrid nanocomposites exhibited high stability and recyclability during the IC dye degradation process. Herein, both GO sheets and Gd3+ ion were excellent co-catalysts and their presence promote the reaction sites and synergistically enhanced the photocatalytic degradation of IC dye. Also, the smaller effective mass caused a high separation of photogenerated charge carriers, thereby promoting the photodegradation efficiency. This work offers a new understanding of designing high-performance TiO2-based photocatalysts for wastewater treatment.

Abstract A73: GD3 ganglioside-enriched extracellular vesicles stimulate melanocyte migration

Abstract Gangliosides are sialic acid-containing glycosphingolipids located mainly in outlet membrane plasma. Tumors usually accumulate gangliosides as disialoganglioside GD3 which is widely expressed in melanomas and neuroblastomas. GD3 has been associated with tumor progression, conferring tumorigenic characteristics to cells such as increased proliferation and migration. In order to investigate the role of GD3 in cell migration, we have transfected the GD3 synthase gene (ST8Sia I) in a melanocyte cell line. In this work we have demonstrated that overexpression of GD3 upon transfection of GD3 synthase was associated with an increased migratory response towards laminin-1. GD3 and 9-O-acetyl-GD3 gangliosides, which colocalize with integrins in cell lamellipodia, are positive modulators of integrin function in the migratory response while GD3 was left behind as a molecular footprint. Indeed, addition of exogenous GD3 to the cells stimulated cell migration whereas exogenously added GM3 inhibited it. However, depletion of gangliosides using a glucosylceramide synthase inhibitor led cells more migratory. Glycosphingolipids content modulates FGF-2-induced cell migration as we demonstrated that FGF-2 induces cell migration. However, this effect was abolished after using glucosylceramide synthase inhibitor, suggesting that GD3 may modulate the motogenic activity of FGF-2. Finally, we showed that GD3 synthase transfected melanocytes release extracellular vesicles (EVs) enriched in GD3. These EVs are responsible for modulating cell migration response due to increase average velocity of GD3 negative cells as we showed in a real-time wound-healing assay. This study shows that EVs from a subset of GD3 positive cells may contribute to the horizontal signaling propagation to a different subset of GD3 negative cells. Thus, data present here led us to an important insight into how EVs carrying GD3 ganglioside could participate in intercellular communication modulating cellular migration. Citation Format: Andreia H. Otake, Ana Paula M. Duarte, Renata de Freitas Saito, Alexandre F. Ramos, Roger Chammas. GD3 ganglioside-enriched extracellular vesicles stimulate melanocyte migration [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr A73.

Strong enhancement of the upconversion emission in ZrO2: Yb3+, Er3+, Gd3+ nanocubes synthesized with Na2S

In this work, the structural, morphological and luminescent characterization of ZrO2:Yb3+,Er3+, Gd3+ nanocrystals prepared with Na2S by precipitation method is reported. The XRD spectra showed a mixture of tetragonal (88%) and monoclinic phases (12%) in samples fabricated with and without Na2S. The tetragonal phase (100%) was stabilized by the introduction of the Gd3+. According to TEM images, samples showed a cubic morphology with an average size of 150nm, when both, Na2S and Gd3+ were added. Red (678nm), green (545nm) and ultraviolet (275, 285nm) emissions were obtained as a result of the upconversion process due to the energy transfer between Yb3+–Er3+–Gd3+ ions, under 970nm of excitation. The integrated red band showed an increment of 40% and 125%, for samples prepared with Na2S and combined with Gd3+, respectively, compared to the ZrO2:Yb3+–Er3+ sample. Such increments are explained in terms of the surface pasivation by using Na2S during the synthesis process and the role of Gd3+ as a reservoir of energy from Er3+.

Investigation of the Effect of Gd3+ on Host-to-Europium Transfer Efficiency in (Y,Gd)BO3:Eu3+ Under VUV Excitation

Using reflectance and excitation spectroscopy, host-to-Eu3+ energy transfer efficiencies in YBO3:Gd,Eu under vacuum ultraviolet excitation have been calculated, at various concentrations of both dopants. As the Gd3+ concentration is increased, an increase in the transfer efficiency to Eu3+ is observed, consistent with prior spectroscopic studies. The role of Gd3+ in these materials is discussed quantitatively in terms of α/β ratios calculated from fits of the transfer efficiency data using accepted kinetic models. Some increase in the effective electron−hole mobility and capture by Eu3+ is observed at 5 mol % Gd3+, and extremely efficient energy migration is observed by 30 mol % Gd3+.

Photoluminescence properties of BaGdB9O16:Tb3+ codoped Zn2+ or Ce3+ under ultraviolet and vacuum ultraviolet excitation

Single phase of Ba1−xZnxGd0.75Tb0.25B9O16 and BaGd0.75−xCexTb0.25B9O16 (0 ≤ x ≤ 0.125) was prepared by the solid-state reaction. Under 254 nm excitation, Zn2+ impaired the emission of Tb3+; Ce3+ sensitized the luminescence of Tb3+ ascribing to the energy transfer of Ce3+ → Tb3+ and/or Ce3+ → Gd3+ → Tb3+ occurring, and the optimum emission was observed at x = 0.05 in BaGd0.75−xCexTb0.25B9O16. Under 147 nm excitation, Zn2+ sensitized the emission of Tb3+ and the optimum emission was obtained at x = 0.075 in Ba1−xZnxGd0.75Tb0.25B9O16, which could be due to the fact that the energy absorption relating to Zn2+ occurred and the absorbed energy was transferred to Tb3+ finally; Ce3+ depressed the luminescence of Tb3+, which could be attributed to the fact that Ce3+ has no absorption in vacuum ultraviolet region and the role of Gd3+ was weakened. Compared with BaGd0.75Tb0.25B9O16 and the commercial phosphor Zn2SiO4:Mn2+, the optimum phosphor Ba0.925Zn0.075Gd0.75Tb0.25B9O16 exhibited about 127% and 51% integrated emission intensity respectively and the shorter decay time of about 2.822 ms under 147 nm excitation.

The Role of Gd3 + in the Luminescence of Several Eu3 + Activated Borate Phosphors under VUV Excitation

The role of in the luminescence of several activated borate phosphors was examined. The results showed that under excitation, the photoluminescence of was improved with the incorporation of in the systems of and , while in the case of and , the luminescence of was decreased when was introduced into the host lattice. A simple energy band model according to the location of lanthanide energy levels relative to the conduction band and valence band of the host lattice was proposed to explain the phenomena.

Ganglioside GD3 promotes cell growth and invasion through p130Cas and paxillin in malignant melanoma cells

Although ganglioside GD3 levels are highly elevated in malignant melanomas, the role of GD3 in melanomas' malignant properties has not been clearly shown. To investigate this problem, we genetically generated GD3-positive (GD3+) transfectant cells from a GD3-negative (GD3-) mutant line SK-MEL-28-N1 and analyzed the phenotypic changes in the transfected cells. GD3+ cells showed markedly increased cell growth and invasive characteristics. Two bands that underwent stronger tyrosine phosphorylation in GD3+ cell lines than in controls after treatment with FCS were found with molecular masses of 130 and 68 kDa. They were identified as p130Cas and paxillin by sequential immunoprecipitation. Their roles in cell growth and invasion were analyzed with a small interfering RNA (siRNA) approach. Cell growth, as analyzed by BrdUrd uptake, was strongly suppressed in GD3+ cells to near the levels of GD3- cells when treated with siRNA for p130Cas but not when treated with siRNA for paxillin. However, treatment with siRNAs of either p130Cas or paxillin resulted in the marked suppression of the invasive activity of GD3+ cells almost to the levels of control cells. These results suggested that these two molecules function as effectors of GD3-mediated signaling, leading to such malignant properties as rapid cell growth and invasion.