Bifunctional Eu(3+)-doped Gd(2)O(3) nanoparticles as a luminescent and T(1) contrast agent for stem cell labeling

Novel Scintillating Nanoparticles for Potential Application in Photodynamic Cancer Therapy

The development of X-ray-absorbing scintillating nanoparticles is of high interest for solving the short penetration depth problem of visible and infrared light in photodynamic therapy (PDT). Thus, these nanoparticles are considered a promising treatment for several types of cancer. Herein, gadolinium oxide nanoparticles doped with europium ions (Gd₂O₃:Eu³⁺) were obtained by using polyvinyl alcohol as a capping agent. Hybrid silica nanoparticles decorated with europium-doped gadolinium oxide (SiO₂-Gd₂O₃:Eu³⁺) were also prepared through the impregnation method. The synthesized nanoparticles were structurally characterized and tested to analyze their biocompatibility. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy confirmed the high crystallinity and purity of the Gd₂O₃:Eu³⁺ particles and the homogeneous distribution of nanostructured rare earth oxides throughout the fumed silica matrix for SiO₂-Gd₂O₃:Eu³⁺. Both nanoparticles displayed stable negative ζ-potentials. The photoluminescence properties of the materials were obtained using a Xe lamp as an excitation source, and they exhibited characteristic Eu³⁺ bands, including at 610 nm, which is the most intense transition band of this ion. Cytotoxicity studies on mouse glioblastoma GL261 cells indicated that these materials appear to be nontoxic from 10 to 500 μg·mL^-1 and show a small reduction in viability in non-tumor cell lines. All these findings demonstrate their possible use as alternative materials in PDT.

Investigation of Gd2O3: Er3+/Yb3+ Upconversion Nanoparticles (UCNPs) as a Multi-model Contrast Agent for Functional Optical Coherence Tomography (fOCT)

Currently, upconversion nanoparticles (UCNPs) implanted as a contrast agent for optical coherence tomography (OCT) system due to its biocompatibility, anti-stock emission, narrow emission bandwidth non-photobleaching effects etc., but it was not used as multi model imaging probe. We synthesized multimodal imaging probe having upconversion property along with paramagnetic property and used as dual contrast agents for Photothermal Optical Coherence Tomography (PTOCT) and Magnetomotive Optical Coherence Tomography (MMOCT). The synthesized Gd₂O₃:Er³⁺/Yb³⁺ UCNPs shows the bright yellow upconversion emission, biocompatibility with hydrophilic property. A custom built SSOCT setup modified for PTOCT and MMOCT imaging along with custom MATLAB algorithm for signal extraction. A dynamic study was performed with synthesized UCNPs as an imaging probe and functional OCT system for targeted imaging. This shows the utility of the Gd₂O₃:Er³⁺/Yb³⁺ UCNPs as molecular probe for targeted imaging applications.

Biogenic approach to synthesize rod shaped Gd2 O3 nanoparticles and its optimization using response surface methodology-Box-Behnken design model

The rare earth metal oxide nanoparticles such as gadolinium oxide nanoparticles (Gd₂ O₃ NPs) have been synthesized by green synthesis process using methanolic extract of Moringa oleifera (M oleifera) peel. In this process, the Gd₂ O₃ NPs formation was observed at 280-300 nm in UV-Vis spectroscopy. The XRD pattern of the synthesized Gd₂ O₃ NPs was exactly matched with JCPDS No 3-065-3181which confirms the crystalline nature of Gd₂ O₃ NPs. In addition, Energy-dispersive X-ray spectroscopy (EDX) analysis was stated that Gd and O elements were present as 70.31 and 29.69%, respectively in Gd₂ O₃ NPs. The SEM and TEM analysis were said Gd₂ O₃ NPs are in rod shape and 26 ± 2 nm in size. Further the synthesized Gd₂ O₃ NPs were confirmed by X-ray photoemission spectroscopy (XPS). The synthesized Gd₂ O₃ NPs were further examined for anti-fungal activity against Alternaria saloni (A saloni) and Sclerrotium rolfsii (S rolfsii) and it showed moderate activity. Also, Gd₂ O₃ NPs evaluated as good antibacterial agent against different Gram +ve and Gram -ve bacteria. Moreover, the toxicity of the Gd₂ O₃ NPs on red blood cells (RBCs) of the human blood was determined using hemolytic assay, the obtained results were stated the synthesized Gd₂ O₃ NPs are nontoxic to the human erythrocytes. The photocatalytic activity against malachite green (MG) dye was tested and confirmed as 92% of dye was degraded within 2 hr by Gd₂ O₃ NPs. The results were stated the green synthesized Gd₂ O₃ NPs are good anti-fungal agents, nontoxic and we can use as a photocatalyst. Copyright © 2019 John Wiley & Sons, Ltd.

Ultra-wide range field-dependent measurements of the relaxivity of Gd1-xEuxVO4 nanoparticle contrast agents using a mechanical sample-shuttling relaxometer

The current trend for Magnetic Resonance Imaging points towards higher magnetic fields. Even though sensitivity and resolution are increased in stronger fields, T1 contrast is often reduced, and this represents a challenge for contrast agent design. Field-dependent measurements of relaxivity are thus important to characterize contrast agents. At present, the field-dependent curves of relaxivity are usually carried out in the field range of 0 T to 2 T, using fast field cycling relaxometers. Here, we employ a high-speed sample shuttling device to switch the magnetic fields experienced by the nuclei between virtually zero field, and the center of any commercial spectrometer. We apply this approach on rare-earth (mixed Gadolinium-Europium) vanadate nanoparticles, and obtain the dispersion curves from very low magnetic field up to 11.7 T. In contrast to the relaxivity profiles of Gd chelates, commonly used for clinical applications, which display a plateau and then a decrease for increasing magnetic fields, these nanoparticles provide maximum contrast enhancement for magnetic fields around 1–1.5 T. These field-dependent curves are fitted using the so-called Magnetic Particle (MP) model and the extracted parameters discussed as a function of particle size and composition. We finally comment on the new possibilities offered by this approach.

High performance magneto-fluorescent nanoparticles assembled from terbium and gadolinium 1,3-diketones

Polyelectrolyte-coated nanoparticles consisting of terbium and gadolinium complexes with calix[4]arene tetra-diketone ligand were first synthesized. The antenna effect of the ligand on Tb(III) green luminescence and the presence of water molecules in the coordination sphere of Gd(III) bring strong luminescent and magnetic performance to the core-shell nanoparticles. The size and the core-shell morphology of the colloids were studied using transmission electron microscopy and dynamic light scattering. The correlation between photophysical and magnetic properties of the nanoparticles and their core composition was highlighted. The core composition was optimized for the longitudinal relaxivity to be greater than that of the commercial magnetic resonance imaging (MRI) contrast agents together with high level of Tb(III)-centered luminescence. The tuning of both magnetic and luminescent output of nanoparticles is obtained via the simple variation of lanthanide chelates concentrations in the initial synthetic solution. The exposure of the pheochromocytoma 12 (PC 12) tumor cells and periphery human blood lymphocytes to nanoparticles results in negligible effect on cell viability, decreased platelet aggregation and bright coloring, indicating the nanoparticles as promising candidates for dual magneto-fluorescent bioimaging.

Mixed lanthanide oxide nanoparticles as dual imaging agent in biomedicine

There is no doubt that the molecular imaging is an extremely important technique in diagnosing diseases. Dual imaging is emerging as a step forward in molecular imaging technique because it can provide us with more information useful for diagnosing diseases than single imaging. Therefore, diverse dual imaging modalities should be developed. Molecular imaging generally relies on imaging agents. Mixed lanthanide oxide nanoparticles could be valuable materials for dual magnetic resonance imaging (MRI)-fluorescent imaging (FI) because they have both excellent and diverse magnetic and fluorescent properties useful for dual MRI-FI, depending on lanthanide ions used. Since they are mixed nanoparticles, they are compact, robust, and stable, which is extremely useful for biomedical applications. They can be also easily synthesized with facile composition control. In this study, we explored three systems of ultrasmall mixed lanthanide (Dy/Eu, Ho/Eu, and Ho/Tb) oxide nanoparticles to demonstrate their usefulness as dual T₂ MRI–FI agents.

Nanotechnology and stem cell therapy for cardiovascular diseases: potential applications

The use of stem cell therapy for the treatment of cardiovascular diseases has generated significant interest in recent years. Limitations to the clinical application of this therapy center on issues of stem cell delivery, engraftment, and fate. Nanotechnology-based cell labeling and imaging techniques facilitate stem cell tracking and engraftment studies. Nanotechnology also brings exciting new opportunities to translational stem cell research as it enables the controlled engineering of nanoparticles and nanomaterials that can properly relate to the physical scale of cell-cell and cell-niche interactions. This review summarizes the most relevant potential applications of nanoscale technologies to the field of stem cell therapy for the treatment of cardiovascular diseases.

Magnetic and optical properties of multifunctional core-shell radioluminescence nanoparticles

When X-rays irradiate radioluminescence nanoparticles, they generate visible and near infrared light that can penetrate through centimeters of tissue. X-ray luminescence tomography (XLT) maps the location of these radioluminescent contrast agents at high resolution by scanning a narrow X-ray beam through the tissue sample and collecting the luminescence at every position. Adding magnetic functionality to these radioluminescent particles would enable them to be guided, oriented, and heated using external magnetic fields, while their location and spectrum could be imaged with XLT and complementary magnetic resonance imaging. In this work, multifunctional monodispersed magnetic radioluminescent nanoparticles were developed as potential drug delivery carriers and radioluminescence imaging agents. The particles consisted of a spindle-shaped magnetic γ-Fe2O3 core and a radioluminescent europium-doped gadolinium oxide shell. Particles with solid iron oxide cores displayed saturation magnetizations consistent with their ~13% core volume, however, the iron oxide quenched their luminescence. In order to increase the luminescence, we partially etched the iron oxide core in oxalic acid while preserving the radioluminescent shell. The core size was controlled by the etching time which in turn affected the particles' luminescence and magnetic properties. Particles with intermediate core sizes displayed both strong magnetophoresis and luminescence properties. They also served as MRI contrast agents with relaxivities of up to 58 mM-1s-1 (r2) and 120 mM-1s-1 (r2*). These particles offer promising multimodal MRI/fluorescence/X-ray luminescence contrast agents. Our core-shell synthesis technique offers a flexible method to control particle size, shape, and composition for a wide range of biological applications of magnetic/luminescent nanoparticles.