Gd Concentration Research Articles

White light emitting nanocrystalline Y1−xGdxPO4:Dy3+ and improved PLQY on Gd3+ co-doping

White Light emitting phosphors are in the realm of scientific evolution owing to their several superior photophysical features and maximum commercial reach. Here in this work we have carried out doping of Dy3+ in Y1-xGdxPO4 wherein we have moved from YPO4 to GdPO4 to harness the potential of dysprosium ion in achieving white light emission and correlating the structural evolution in these phosphates with luminescence properties. Y1-xGdxPO4:Dy3+ phosphor has been synthesized using co-precipitation method and characterized using x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), time resolved photoluminescence (TRPL) and positron annihilation lifetime spectroscopy (PALS). Based on emission spectroscopy it was deciphered that Dy3+ lacks inversion symmetry in all the samples with asymmetry ratio of ∼1.2 in YPO4 and 2.75 in GdPO4. The same is correlated structurally wherein YO8 is in dodecahedron with D2d symmetry while GdO8 is highly distorted. The photoluminescence quantum yield (PLQY) increases monotonically with Gd3+ insertion and GdPO4:Dy3+ showing the highest PLQY endowed by enhanced asymmetry around Dy3+ making the f-f transitions more relaxed and allowable. The surface defects as revealed by positrons also decreased with increase in Gd content and that also aids the increase in emission intensities. Moreover PLQY value was higher with 274 nm compared to excitation with f-f transitions (∼351 nm) due to Gd3+ to Dy3+ energy transfer. The phosphors have similar color coordinate value and correlated color temperature of (∼0.33, ∼0.36), ∼5400 K, respectively, which are close to the bluish cool-white emission. Therefore, the GdPO4:Dy3+ phosphor with longer excited state lifetime, moderate PLQY, effective CIE coordinates close to white and high CCT can be explored for generation of cool white light emission excitable by UV/NUV LED for solid-state lighting and optoelectronic devices.

Multimodal analytical tools for the molecular and elemental characterisation of lesions in brain tissue of multiple sclerosis patients

Multiple sclerosis (MS) is a prevalent immune-mediated inflammatory disease of the central nervous system inducing a widespread degradation of myelin and resulting in neurological deficits. Recent advances in molecular and atomic imaging provide the means to probe the microenvironment in affected brain tissues at an unprecedented level of detail and may provide new insights. This study showcases state-of-the-art spectroscopic and mass spectrometric techniques to compare distributions of molecular and atomic entities in MS lesions and surrounding brain tissues.MS brains underwent post-mortem magnetic resonance imaging (MRI) to locate and subsequently dissect MS lesions and surrounding white matter. Digests of lesions and unaffected white matter were analysed via ICP-MS/MS revealing significant differences in concentrations of Li, Mg, P, K, Mn, V, Rb, Ag, Gd and Bi. Micro x-ray fluorescence spectroscopy (μXRF) and laser ablation – inductively coupled plasma – time of flight – mass spectrometry (LA-ICP-ToF-MS) were used as micro-analytical imaging techniques to study distributions of both endogenous and xenobiotic elements. The essential trace elements Fe, Cu and Zn were subsequently calibrated using in-house manufactured gelatine standards. Lipid distributions were studied using IR-micro spectroscopy and matrix assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI). MALDI-MSI was complemented with high-resolution tandem mass spectrometry and trapped ion mobility spectroscopy for the annotation of specified phospho- and sphingolipids, revealing specific lipid species decreased in MS lesions compared to surrounding white matter.This explorative study demonstrated that modern molecular and atomic mapping techniques provide high-resolution imaging for relevant bio-indicative entities which may complement our current understanding of the underlying pathophysiological processes.

Effect of ultralow Dy and Gd contents on surface crystallization and domain wall motion of FeCuSiBNbMo alloys

Surface crystallization of Fe-based melt-spun ribbons with high saturation induction leads to the formation of coarse grains after nanocrystallization, which results in a deterioration of the soft magnetic properties. Herein, doping with an ultralow concentration (0.1 at.%) of RE (RE = Dy and Gd) inhibits the surface crystallization of melt-spun FeCuSiBNbMo samples using industrial-grade Nb–Fe raw materials. This inhibition of surface crystallization promotes the formation of uniform and ultrafine nanograins after optimal annealing. Furthermore, the movement of domain wall is significantly affected by the presence of large grains (∼600 nm) in the free surface, which exerts a strong pinning effect on the domain wall motion. This pinning effect can be attributed to the higher magnetic anisotropy energy of the free surface compared to that of the nanocrystal region. The low coercivity observed in the samples with 0.1 at.% Dy and Gd addition is ascribed to the presence of dense and ultrafine nanocrystals, low effective magnetic anisotropy, and a weak pinning effect. This work provides insights into the relationship between surface crystallization, coercivity, domain wall motion, and magnetic anisotropy energy in Fe-based nanocrystalline ribbons.

A new potential choice for scintillation fiber

In order to enrich the application demands of neutron detection field, this study prepared a series of Ce3+/Gd3+ co-doped borosilicate scintillating glass materials. The ultraviolet (UV) absorption edges were all below 400 nm. The optical band gap was shortened from 3.48 eV to 3.24 eV as well as the optical basicity increased from 0.4941 to 0.5063 with the added concentration of Gd3+ ions. When the samples were excited by a 330 nm light source, the central wavelength of the emission spectra was 375 nm. The fluorescence lifetime of the sample was 30.99 ns. The emission intensity of the G2 sample increases linearly with the increase of X-ray excitation current, and has a stable optical response at 374 nm. The G2 glass fiber with the highest fluorescence intensity had a prominent emission peak at 375 nm and the fluorescence lifetime of 2.22 ns.

Chelating ligand-bridged IO-Gd nanoparticles with enhanced contrast performance for dual-mode MRI

Magnetic resonance imaging (MRI) is a non-invasive medical imaging technique that has been widely applied in the clinical diagnosis of diseases across various fields. Currently, there is a dearth of high-performance dual-mode contrast agents that provide precise diagnostic information for complex diseases. In this study, iron oxide-gadolinium nanoparticles (IO-Gd NPs) bridged by hydrophilic ligand ethylenediamine tetramethylenephosphonic acid (EDTMP) are designed inspired by Solomon-Bloembergen–Morgan (SBM) theory, where T1 and T2 relaxivity increase with a reduction in Gd content. In particular, the NPs with minimum Gd content exhibit excellent dual-mode contrast performance (r1 = 94.42 mM−1 s−1, r2 = 343.62 mM−1 s−1). The underlying mechanism is that the bridged EDTMP coordinate limits Gd tumbling and forces Gd3+ to expose itself to the surface of the NPs. This provides more opportunities for water molecules to coordinate with Gd3+ and significantly enhances proton relaxivity. Moreover, the hydrophilicity of the ligand enhances the water dispersion stability of the NPs and increases the exchange rate of water protons near the NPs, further enhancing the dual-mode contrast effect. Finally, the biocompatibility and in vitro/vivo imaging performances of the IO@EDTMP-Gd NPs are systematically evaluated, and the results demonstrate their potential as dual-mode contrast agents. This study provides a new strategy for developing dual-mode MRI contrast agents that can further improve the accuracy of MRI in the diagnosis of complex diseases.

Gd2O3-based contrasting agents for photon-counting computed tomography: Effect of structure, composition, and particle size

New contrast agents (CAs) for photon-counting computed tomography (PCCT) were synthesized, including Gd2O3@SiO2 core-shell structures and surface-modified Gd2O3–SiO2–C3H6NH2 nanoparticles. Their composition and structure were assessed by IR spectroscopy, scanning electron microscopy, X-ray phase analysis, and thermogravimetric analysis. The X-ray attenuation of synthesized particles Gd2O3@SiO2 with a size of 150–200 nm and Gd2O3–SiO2–C3H6NH2 with a size of 200–300 nm, as well as the sample of Gd2O3 with a particle size of 300–500 nm in gelatine dispersion, was investigated in phantom studies by PCCT. Energy-specific X-ray attenuation properties of all CA types correlated with their Gd concentrations. Gd2O3 demonstrated higher X-ray attenuation compared to Gd2O3@SiO2 and Gd2O3–SiO2–C3H6NH2 at the same concentrations of Gd, which can be explained by the effect of the SiO2 shells.

Stability of the Macrocyclic Gd-DOTA Contrast Agent (DOTAREM) under Different Estuarine Environmental Conditions

Gadolinium-based contrast agents (GBCA) are complexes, highly stable in vivo, used in magnetic resonance imaging (MRI), administered in patients and then eliminated via the renal system, passing through wastewater treatment plants (WWTP) before being discarded in the receiving medium, without apparent removal. In this study, it was examined whether different exposure periods to several environmental parameters (solar radiation, different salinities, temperatures and pH) will influence the stability of these complexes, namely, the Gd-DOTA. Gd-DOTA solutions were processed in a seaFAST-pico saline matrix pre-concentration and elimination system, and Gd concentrations were determined using ICP-MS. The results showed that the complex remained stable in fresh, brackish and saline water environments, even when exposed to extreme temperatures (40 °C) or slightly acidic to basic conditions (6–10), for an exposure period of 96 h. A small increase in the free Gd concentration was observed after 18 days when exposed to pH < 4, in all tested salinities (0, 18 and 36 PSU), with a degradation increase of up to 29%, after 5 weeks of exposure in freshwater. When exposed to direct solar radiation, a low Gd-DOTA degradation (4%) was observed after 24 h at salinity 18 PSU and remained constant until the end of the exposure period (96 h), while the remaining salinities showed negligible values.

Temperature-dependence of anomalous Hall effect in Ta-(GdFeCo)δ-Ta films with vertical composition gradients

Ferrimagnetic rare-earth (RE) – transition-metal (TM) alloys are considered small ferromagnets with antiferromagnetic exchange in sublattices, which makes them a preferable choice for future ultrafast memory-related applications. Here, we explore the magnetic properties of two GdFeCo thin films with tailored vertical composition gradients, achieved by gradually varying Gd concentration across the film thickness. The temperature-dependent magnetic behavior of these films is investigated using anomalous Hall effect (AHE) measurements and SQUID magnetometry. Both films exhibit perpendicular magnetic anisotropy with distinct coercivities, indicating variations in their magnetic properties. The films show RE-dominant behavior at 300 K. Moreover, for the positive composition gradient (+δ) film, the compensation temperature is around 350 K, while the film with a negative gradient (−δ) exhibits a compensation temperature above 400 K. Furthermore, the spin-flop behavior and AHE sign reversal provide insights into the sublattice dominance and exchange interactions within the films. The magnitude of ΔRXY (the difference in AHE resistance at different magnetic fields) is shown to be sensitive to the composition gradient, indicating stronger perpendicular magnetic anisotropy for the “−δ” sample. This study demonstrates the potential of composition engineering to tailor the magnetic characteristics of ferrimagnetic materials for specific spintronics applications.

Religious activities and their impacts on the surface sediments of two lakes in Bali, Indonesia: A case study from Lake Buyan and Lake Tamblingan

Industrial and agricultural activities, as well as settlements, have changed many lacustrine environments, as recorded in lake sediments. In this study, concentrations of trace metals and rare earth elements (REEs), along with the mass-specific magnetic susceptibility measured at low frequency (470 Hz), termed χLF, were used to elucidate the anthropogenic impacts related to religious activities in 2 lakes (Buyan and Tamblingan) on Bali Island, Indonesia. The predominantly Hindu populations of Bali are known to hold various religious activities in puras, or Balinese temples, in these lakes. There are 8 puras in Lake Tamblingan and only 3 puras in Lake Buyan. In these religious activities, offerings, which might include metallic objects, were thrown into the lakes. Measurements on surface sediments from 20 locations in Lake Buyan and 16 locations in Lake Tamblingan show that χLF values and concentrations of trace metals and REEs are higher in the sediments of Lake Tamblingan compared to those of Lake Buyan, except for concentrations of SiO2 and Gd. The average χLF value of Tamblingan’s samples is 492.6 (±282.4) × 10−8 m3/kg, while that of Buyan’s samples is 372.0 (±246.6) × 10−8 m3/kg. The average concentrations of Fe and Al in Tamblingan’s samples are 5.934 and 4.941 (in % weight), respectively, while those of Buyan’s samples are 4.445 and 3.434 (in % weight), respectively. The average concentrations of Ce and Nd in Tamblingan’s samples are 2.066 and 1.494 (in ppm), respectively, while those in Buyan’s samples are 1.423 and 1.105 (in ppm), respectively. Concentrations of trace metals and REEs, as well as χLF, are higher in locations close to the puras around the lakes. For instance, the χLF of location T11 near Pura Dalem Tamblingan is 975.9 (±99.3) × 10−8 m3/kg, while the concentrations of Fe and Al in this location are 9.790 and 14.090 (in % weight). Furthermore, the Ce and Nd concentrations in T11 are 3.635 and 2.443 ppm, respectively. Based on these results, we can say that the surface sediments of Lakes Buyan and Tamblingan have been changed by human activities, mostly religious ones.

Effect of route production and doping concentration on luminescence response of MgB4O7: Gd phosphor

This work studied the synthesis route and gadolinium (Gd) doping concentration on magnesium tetraborate (MBO) luminescence response. The material was synthesized by solid-state reaction techniques with two different procedures (Routes A and B) for three different Gd concentrations (0.2, 0.3, and 0.7 %wt). Route A consisted of the synthesis of the MBO matrix and subsequently add Gd2O3 as an activator. Route B the material was obtained after mixing and co-milling the precursors and the activator together prior to synthesis. Rietveld refinement of experimental X-ray diffraction data indicates that the MgB4O7:Gd compounds exhibit single phases consistent with orthorhombic symmetry (space group Pbca (61)). These compounds also evidenced contributions Gd dopant concentrations in MgB4O7 matching the cubic symmetry of the material. The electron microscopic scan surface morphological study exhibited the formation of polycrystalline material with diverse grain shapes for the two production routes. Compositional characterization by electron X-ray energy spectroscopy suggested that there were no other elements besides the expected elements in the material. The optical response by diffuse reflectance spectroscopy estimated the energy gap from the fundamental absorption of the undoped host. Optically stimulated luminescence response suggested that MgB4O7:Gd 0.7%wt (route B) sensitivity is 2.1 times higher than that presented in MgB4O7:Gd 0.3 % (route A). Thermoluminescence experiments showed that the optimum Gd dopant concentrations for the most intense dosimetric peak of phosphorus MgB4O7 fabricated using routes A and B were 0.3 % (main peak: 209 °C) and 0.7 % (main peak: 276 °C), respectively. The thermoluminescence sensitivity of MgB4O7:Gd 0.3%wt (route A) is 3.5 times higher than the sensitivity of MgB4O7:Gd 0.7%wt (route B).

Accelerating and decelerating effects of Gd content and peak-aging treatment on the grain growth of magnesium

This short communication concerns the dependence of thermal stability of fine grains in Mg alloy on the Gd content. The enhanced thermal stability via increasing Gd content can be reflected by the SRX mechanism and corresponding boundary migration ability. In the low Gd-alloyed Mg, continuous SRX dominates the annealing process via dislocation re-arrangement. The grain boundaries composed by dislocations can easily migrate, since the uniform Gd solute distribution provides limited delaying effect. In the high Gd-alloyed Mg, discontinuous SRX dominates the annealing process via consuming dislocations for grain nucleation. The grain boundaries can hardly migrate due to the strong delaying effect provided by the Gd-segregation along grain boundaries. But unexpectedly, peak-aging can deteriorate the decelerated effect of high Gd-alloying owing to the absent Gd-segregation. Consequently, an accelerated grain growth rate is attained, even faster than that in the low Gd-alloyed Mg.

Electrical conduction mechanism in multiferroic Gd doped GaFeO3

A detail analysis on the structural, morphological, dielectric, conductivity, ferroelectric, magnetic and electrical behaviour of Gd doped GaFeO3 prepared by mixed oxide method is presented. XRD analysis, by using Rietveld refinement method, validates that all the samples have single phase orthorhombic structure. Decrement in the grain size with rise in Gd content is found from FESEM analysis. The dispersive characteristic of dielectric constant is described by the Maxwell-Wagner model and Koop's theory. The value of εr is found to increase with Gd content. The modified Debye formula is used to fit εr with frequency data, which indicates the existence of more than one relaxation processes. The frequency dependant ac conductivity curve is found to obey Jonscher's power law and the conduction mechanism for all the samples is explained by of small polaron hopping (SPH) transport model. The modulus and impedance spectra confirms the presence of non- Debye type of relaxation. The presence of semicircular curves of complex impedance plot suggests the effect of grain boundary contribution to the conduction process for all the samples at low temperatures. The value of remanent polarization is found to fall with Gd content. From M-H loop, magnetisation at M (30kOe) is found to rise while non-saturation is found to decrease with Gd content and analysed on the basis of Law of Approach.

Defect related photocatalytic and photoluminescent characteristics of Gd-doped SnO2 nanoparticles with different shapes

A new method for the preparation of Gd-doped SnO2 nanoparticles based on the precipitation method followed by hydrothermal treatment has been developed. Two different shape series of nanoparticles with different Gd content were obtained and fully characterized. Wide number of parameters, including lattice parameters, crystallite size, particle size, surface composition, oxygen vacancies, structural defects, band gap energy, luminescent spectra, band structure and density of states were determined.It was shown that the mechanism of oriented attachment of nanoparticle growth is stimulated during hydrothermal treatment. Quantum computer calculations of the interaction energies of oriented nanoparticles were performed and the role of ions in the reaction media was revealed.A study of the photoluminescence of the obtained nanoparticles was carried out, showing a blue photoluminescence corresponding to the oxygen vacancies, indicating their presence.Photocatalytic activity of nanoparticles when irradiated with visible light was shown, which is explained by quantum chemical calculations and demonstrated in the example of a colored solution of the organic dye methylene blue. The relation between the morphological and structural properties of nanoparticles and their photocatalytic properties has been studied in detail. A high degradation percentage is achieved using a regular commercially available LED lamp with a visible light spectrum.Novelty of the work lies in obtaining series of samples with various parameters, detailed studies of oriented attachment mechanism and impact of the nanoparticle parameters on photocatalytic properties. A concept for the development of efficient photocatalysts based on chemical and computational experiments is proposed.

Effect of Gd addition on the microwave absorption properties of FeSiAl composite

FeSiAl-xGd composites were fabricated by vacuum sintering technique in this paper. The electromagnetic parameters of the composites were modulated by changing the content of Gd. It was demonstrated that the addition of Gd was favourable to the microwave absorption of FeSiAl composites. The minimum reflection loss (RL) of FeSiAl-3Gd composites can be up to −54.6 dB at 5.87 GHz when thickness is 3.5 mm. Radar cross section (RCS) simulation of FeSiAl-3Gd sample using CST with RCS reduction value of 24.38 dBm2. Its excellent microwave absorbing performance can be attributed to two factors. Firstly, the synergistic effect of FeSiAl and Gd improves the microwave absorption of the composites. Finally, Gd doping alters the surface morphology of the composites and provides multiple scattering paths, resulting in multiple losses of electromagnetic waves.

Effect of rare earth substitution on electromagnetic and microwave absorption properties of nickel-cobalt nano ferrite

Oxygen vacancy engineering is one of the most effective strategies for tuning the microstructural properties of oxide nanomaterials. However, the connection between oxygen vacancies and electromagnetic (EM) wave absorption capacities is unclear. Herein, oxygen vacancy-boosted microwave absorption is realized over Gd-doped Ni0.5Co0.5Fe2O4 (NCFO) nanoceramics. All magnetic properties are studied with the influence of induced lattice strain. Except for Ni0.5Co0.5 Gd0.075Fe1.925O4 (NCFOG3), which has an elevated saturation magnetization (Ms) of 63 emu/g, the Ms decreases with increasing Gd content. In addition, remnant magnetization (Mr), coercivity (Hc), and anisotropic constant (K) increased until Ni0.5Co0.5 Gd0.050Fe1.95O4 (NCFOG2) and then declined. The EM wave parameters: dielectric permittivity (ϵ'), magnetic permeability (μ'), dielectric loss (ϵ''), and magnetic loss (μ'') are systematically examined and found in the ranges of 2.07–3.5, 1.73–4.7, (4 × 10-2) – (2.2 × 10-1) and 0.18–0.35 respectively. Our finding shows that a small amount of Gd favors the high oxygen vacancy concentration, an appropriate lattice defect, and high magnetic and dielectric losses. The possible mechanism for EM wave absorption revealed the largely localized electrons and dipole centers created by the numerous oxygen vacancies causing the multiple reflection and scattering, which enhanced conductive loss, defect, and dipole polarizations. The maximum reflection loss (RL) -28.37 dB is observed at 17.80 GHz of a 2 mm thick sample for NCFOG3. This research reveals a distinct link between oxygen vacancy defects and EM wave dissipation capability, providing important information for developing better EM wave absorbents.

Microstructure, thermophysical properties and neutron shielding properties of Gd/316 L composites for spent nuclear fuel transportation and storage

In this paper, (0.5–5.0 wt%)Gd/316 L composites were prepared by vacuum arc melting, and the microstructure, thermophysical properties, and neutron shielding properties were analyzed deeply. The results showed that the Gd/316 L composites started solidification in primary ferrite mode and terminated solidification by a peritectic-type reaction forming (Fe, Ni, Cr)3Gd that is rich in Ni and Gd. In the peritectic-type reaction, local convection in the Ni-rich and Gd-rich peritectic liquid phase leads to the formation of multiple variants of (Fe, Ni, Cr)3Gd. The higher the Gd content, the greater the amount of (Fe, Ni, Cr)3Gd and ferrite, and the harder it is to keep the austenitic matrix of 316 L stainless steel. The solidification temperature range of Gd/316 L composites is 1074–1460 °C, which severely limits the ability to further process it by high-temperature deformation techniques such as hot rolling or hot forging. (Fe, Ni, Cr)3Gd preferentially nucleates and grows in the triangular region of austenite grain boundaries at 1074 °C. At 50–500 °C, with increasing Gd content, thermal expansion and thermal diffusion coefficients become decrease, and thermal conductivity and specific heat capacity increase. The trend of thermophysical property changes is favorable for SNF transportation and storage applications. The thermal neutron shielding properties of 1.0 wt%Gd/316 L composite is comparable to that of 4.45 wt% B content boron steel and 15 wt%B4C/Al composite. The Gd content in Gd/316 L composites material should not exceed 2.5 wt%. If the Gd content continues to increase, it is of little significance to improving shielding properties and material thinning. A shielding thickness of 3 mm is more appropriate for Gd/316 L composites. Too thin would not provide sufficient mechanical properties and increase processing and manufacturing costs.

Uptake of Gadolinium-Based Contrast Agents by Blood Cells During Contrast-Enhanced MRI Examination.

Gadolinium-based contrast agents (GBCAs) are routinely used in magnetic resonance imaging (MRI) examinations. However, there is limited knowledge about the interaction with and distribution of the drug in human cells. This lack of knowledge is surprising, given that the first interaction of the drug occurs with blood cells. Moreover, recent studies reported gadolinium (Gd) deposition within organs, such as the brain. Hence, this study is aiming to determine the uptake of GBCA in blood cells of patients undergoing contrast-enhanced MRI (ce-MRI) examination. Human blood was exposed to either gadoterate meglumine (Gd-DOTA) or Eu-DOTA in vitro or was collected from patients undergoing ce-MRI with Gd-DOTA. Uptake of contrast agents (CAs) by blood cells was quantified by Gd measurements using single-cell inductively coupled plasma mass spectrometry (SC-ICP-MS) or, to confirm Gd-DOTA uptake, by a complementary method using Eu-DOTA by time-resolved fluorescence spectroscopy, respectively. Uptake of Gd-DOTA or Eu-DOTA into white blood cells (WBCs) ex vivo was detectable by SC-ICP-MS and time-resolved fluorescence spectroscopy. The intracellular concentrations were estimated to be in the range of 1-3 μM. However, no CA uptake into erythrocytes was detected with either method. In total, 42 patients between 30 and 84 years old (24 men, 18 women) were enrolled. White blood cells' uptake of Gd was measured by SC-ICP-MS. Isolated WBCs from patients who underwent ce-MRI examination showed substantial Gd uptake; however, the studied patient group showed an inhomogeneous distribution of Gd uptake. Measurements immediately after MRI examination indicated 21-444 attogram/WBC, corresponding to an intracellular Gd concentration in the range from 0.2 to 5.5 μM. This study confirms the ex vivo uptake of GBCA by WBCs and provides the first evidence that GBCA is indeed taken up by WBCs in vivo by patients undergoing ce-MRI examination. However, the observed Gd uptake in WBCs does not follow a log-normal distribution commonly observed in the fields of environmental studies, biology, and medicine. Whether cellular uptake of GBCA is linked to the observed deposition of Gd remains unclear. Therefore, studying the interaction between GBCA and human cells may clarify crucial questions about the effects of Gd on patients after MRI examinations.

Evaluation of structural, optical, and magnetic properties of Gd doped MnFe2O4 nanoparticles

In this study, the MnFe2O4 doped Gd (MnGdxFe2-xO4 with x = 0, 0.125, 0.25, and 0.5) magnetic nanoparticles were successfully synthesized and revealed the significant effect of Gd content on structural, optical, and magnetic properties. The replacement of Fe3+ ions by ion Gd3+ ions changed the crystallite size from 8.2 nm (x = 0) to 13.5 nm (x = 0.5). The band gap of Gd-doped MnFe2O4 increased with an increase of the x value. The magnetic curves showed that saturation magnetization (MS) and magnetic anisotropy (K) decreased simultaneously with the concentration of Gd3+ ions. The MS value reduced from 54.0 emu/g (MnFe2O4) to 35.4 emu/g (MnGd0.5Fe1.5O4). The K value dropped from 50.4 kJ/m3 (MnGd0.125Fe1.875O4) to 12.3 kJ/m3 (MnGd0.5Fe1.5O4). The substantial reliance of magnetic anisotropy on the doping concentration, namely this large change in K with a little change in size (8.2 nm–13.5 nm), demonstrated that doping is a suitable method for modifying the values of magnetic anisotropy of materials.

Immunolabelling perturbs the endogenous and antibody-conjugated elemental concentrations during immuno-mass spectrometry imaging

Immuno-mass spectrometry imaging uses lanthanide-conjugated antibodies to spatially quantify biomolecules via laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The multi-element capabilities allow for highly multiplexed analyses that may include both conjugated antibodies and endogenous metals to reveal relationships between disease and chemical composition. Sample handling is known to perturb the composition of the endogenous elements, but there has been little investigation into the effects of immunolabelling and coverslipping. Here, we used cryofixed muscle sections to examine the impact of immunolabelling steps on the concentrations of a Gd-conjugated anti-dystrophin primary antibody, and the endogenous metals Cu and Zn. Primary antibody incubation resulted in a decrease in Zn, and an increase in Cu. Zn was removed from the cytoplasm where it was hypothesised to be more labile, whereas concentrated locations of Zn remained in the cell membrane in all samples that underwent the immunostaining process. Cu increased in concentration and was found mostly in the cell membrane. The concentration of the Gd-conjugated antibody when compared to the standard air-dried sample was not significantly different when coverslipped using an organic mounting medium, whereas use of an aqueous mounting medium significantly reduced the concentration of Gd. These results build on the knowledge of how certain sample handling techniques change elemental concentrations and distributions in tissue sections. Immunolabelling steps impact the concentration of endogenous elements, and separate histological sections are required for the quantitative analysis of endogenous elements and biomolecules. Additionally, coverslipping tissue sections for complementary immunohistochemical/immunofluorescent imaging may compromise the integrity of the elemental label, and organic mounting media are recommended over aqueous mounting media.Graphical

MRI Directed Magnevist Effective to Study Toxicity of Gd-Doped Mesoporous Carbon Nanoparticles in Mice Model.

Magnetic resonance imaging (MRI) has been a valuable and widely used examination technique in clinical diagnosis and prognostic efficacy evaluation. The introduction of MRI contrast agent (CA) improves its sensitivity obviously, particularly with the development of nano-CA, which presents higher contrast enhancement ability. However, systematical evaluation of their toxicity is still limited, hampering their further translation in clinics. In this paper, to systematically evaluate the toxicity of nano-CA, Gd-doped mesoporous carbon nanoparticles (Gd-MCNs) prepared by a one-step hard template method were introduced as a model and clinically used MRI CA, Magnevist (Gd-DTPA) as control. Their in vitro blood compatibility, cellular toxicity, DNA damage, oxidative stress, inflammation response as well as in vivo toxicity and MR imaging behaviors were studied and compared. The experimental results showed that compared with Gd-DTPA, Gd-MCNs displayed negligible influence on the red blood cell shape, aggregation, BSA structure, macrophage morphology and mitochondrial function. Meanwhile, limited ROS and inflammatory cytokine production also illustrated the cellular compatibility of Gd-MCNs. For in vivo toxicity evaluation, Gd-MCNs presented acceptable in vivo biosafety even under 12 times injection for 12 weeks. More importantly, at the same concentration of Gd, Gd-MCNs displayed better contrast enhancement of tumor than Gd-DTPA, mainly coming from its high MRI relaxation rate which is nearly 9 times that of Gd-DTPA. In this paper, we focus on the toxicity evaluation of MRI nano-CA, Gd-MCNs from different angles. With Gd-DTPA as control, Gd-MCNs appeared to be highly biocompatible and safe nanoparticles that possessed promising potentials for the use of MRI nano-CA. In the future, more research on the long-term genotoxicity and the fate of nanoparticles after being swallowed should be performed.