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Gadolinium Doping Enhances the Photoacoustic Signal of Synthetic Melanin Nanoparticles: A Dual Modality Contrast Agent for Stem Cell Imaging.
摘要： In this paper we show that gadolinium-loaded synthetic melanin nanoparticles (Gd(III)-SMNPs) exhibit up to a 40-fold enhanced photoacoustic signal intensity relative to synthetic melanin alone and higher than other metal-chelated SMNPs. This property makes these materials useful as dual labelling agents because Gd(III)-SMNPs also behave as magnetic resonance imaging (MRI) contrast agents. As a proof-of-concept, we used these nanoparticles to label human mesenchymal stem cells (hMSCs). Cellular uptake was confirmed with bright field optical and transmission electron microscopy. The Gd(III)-SMNP labeled stem cells continued to express the stem cell surface markers CD73, CD90, and CD105 and proliferate. The labeled stem cells were subsequently injected intramyocardially in mice, and the tissue was observed by photoacoustic and MR imaging. We found the photoacoustic signal increased as cell number increased (R2 = 0.96) indicating that such an approach could be employed to discriminate between stem cells populations with a limit of detection of 2.3 x 104 cells in in vitro tests. This multimodal photoacoustic/MRI approach combines the excellent temporal resolution of photoacoustics with the anatomic resolution of MRI.
关键词： Photoacoustic Signal,Stem Cell Imaging,Gadolinium,Dual Modality Contrast Agent,Synthetic Melanin Nanoparticles
更新于2025-09-04 15:30:14
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Compact and effective detector of the fast neutrons on a base of Ce doped Gd3Al2Ga3O12 scintillation crystal
摘要： Gadolinium garnet Gd3Al2Ga3O12:Ce crystal is demonstrated to be an excellent scintillation material for detection of fast neutrons for the first time. This is achieved because the material, firstly, has high content of Gd, which absorbs neutrons with following prompt emission of γ-quanta, and, secondly, detects this radiation efficiently thanks to high stopping power and high scintillation light yield. GEANT4 modeling was used to distinguish several characteristic regions in γ-quanta pulse height spectra acquired with GAGG:Ce crystal under neutron irradiation, with energies nearly 90 and 190, and 511 keV, which have different relative intensities depending on incident neutrons kinetic energy. This was approved by measurements on Am-Be neutron source. Sensitivity of the material to neutrons from Am-Be source was compared to 6Li-based glass, and found to be superior, depending on signal selectivity.
关键词： Gamma-rays,Neutrons,Gadolinium,Solid scintillation detectors
更新于2025-09-04 15:30:14
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Folic acid-nanoscale gadolinium-porphyrin metal-organic frameworks: fluorescence and magnetic resonance dual-modality imaging and photodynamic therapy in hepatocellular carcinoma
摘要： Background: Hepatocellular carcinoma (HCC) is the most common primary liver cancer and severely threatens human health. Since the prognosis of advanced HCC remains poor, there is an urgent need to develop new therapeutic approaches. Porphyrin metal-organic frameworks are a class of porous organic-inorganic hybrid functional materials with good biocompatibility. Methods: Gadolinium-porphyrin metal-organic frameworks were used as a skeleton for folic acid (FA) conjugation to synthesize a novel type of nanoparticle, denoted as folic acid-nanoscale gadolinium-porphyrin metal-organic frameworks (FA-NPMOFs). The FA-NPMOFs were characterized using transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric-differential thermal analysis. The biotoxicity and imaging capability of the FA-NPMOFs were determined using HepG2 cells and embryonic and larval zebrafish. The delivery and photodynamic therapeutic effect of FA-NPMOFs were explored in transgenic zebrafish with doxycycline-induced HCC. Results: FA-NPMOFs were spherical in structure with good dispersion and water solubility. They showed low biotoxicity, emitted bright red fluorescence, and exhibited an excellent magnetic resonance imaging capability, both in vitro and in vivo. Meanwhile, the FA-NPMOFs exhibited a strong affinity for folate receptor (FR)-expressing cells and were delivered to the tumor site in a targeted manner. Moreover, HCC tumor cells were eliminated following laser irradiation. Conclusion: FA-NPMOFs can be used for dual-modality imaging and photodynamic therapy in HCC and show promise for use as a carrier in new therapies for HCC and other FR-positive tumors.
关键词： nanoscale gadolinium-porphyrin metal-organic frameworks,folic acid,hepatocellular carcinoma,photodynamic therapy,dual-modality imaging
更新于2025-09-04 15:30:14
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Effect of doping Gd2O3 on dielectric and piezoelectric properties of BaZr0.1Ti0.9O3 ceramics by sol–gel method
摘要： The effects of sintering temperature and doping amount of gadolinium ions on the microstructures and electrical properties of sol gel derived Ba (Zr0.1Ti0.9) O3 + xGd ceramics were investigated in this manuscript. XRD analysis showed that the main crystalline phase of BZT-xGd ceramic samples exhibit a perovskite structure without significantly change. The sample sintered at 1350 °C and doped with gadolinium ions of 0.5 mol% has uniform grain size and compact morphology. And the sample(1350 °C—0.5 mol%) also has a high piezoelectric charge coefficient of 131.33 pC/N, large plane electromechanical coupling coefficient of 0.22, high dielectric constant of 10504, and small dielectric loss of 0.01. The correlation of dielectric and piezoelectric properties of BZT-xGd ceramics with doping amount of Gd3+ ion has been explained by the lattice theory.
关键词： BZT-xGd ceramics,dielectric properties,sol–gel method,gadolinium doping,piezoelectric properties
更新于2025-09-04 15:30:14
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Investigation of Interface Diffusion in Sputter Deposited Gd0.1Ce0.9O1.95 Thin Buffer Layers on Y-Stabilized Zirconia Crystalline Substrates for Solid Oxide Cells Applications
摘要： This paper presents the results concerning the investigation of the morphological and structural properties of Gd0.1Ce0.9O1.95 layers deposited on crystalline (111) YSZ subtrates by RF magnetron sputtering. Room temperature as-grown samples have been annealed at different temperatures from 600°C to 1300°C. Atomic Force Microscopy analysis shows an increase in the average grain size dimensions with increasing annealing temperatures. X-Ray Diffraction measurements indicates a preferential growth of the grains along the (111) direction with a decrease in the evaluated c-axis as a function of the annealing temperature, probably related to an over-oxidation of the samples. X-Ray Reflectivity studies, performed on thin layers annealed at temperatures from 700-1000°C, points out the presence of zones with different densities and roughness at the layer/substrate interface and at the layer/vacuum surface. The behaviour of these zones as a function of temperature has been investigated. The obtained results seem to exclude the presence of consistent inter-diffusion phenomena at the GDC/YSZ interface.
关键词： Solid oxide cells,X-ray reflectivity,Reciprocal space map,RF magnetron sputtering,Yttrium stabilized Zirconia,Gadolinium doped Ceria,Interdiffusion
更新于2025-09-04 15:30:14