Lanthanide Oxide Nanoparticles Research Articles

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.

Synthesis, characterization and crystal structure of three new lanthanide (III) complexes with the [(6-methyl-2-pyridyl)methyl]bis(2-pyridylmethyl)amine (MeTPA) ligand; New precursors for lanthanide (III) oxide nano-particles

Several novel lanthanum (III) complexes of the [(6-methyl-2-pyridyl)methyl]bis(2-pyridylmethyl)amine (MeTPA) ligand with the formula [Ln(MeTPA)Cl3(MeOH)].MeOH (Ln: La (1), Nd (2) and Sm (3)) were successfully synthesized. The complexes were characterized by 1H NMR, mass spectrometry, TGA–DTA as well as elemental analysis. The molecular structures of the three complexes were determined by single-crystal X-ray crystallography. The single-crystal X-ray data revealed that 1, 2 and 3 are isostructural. The prepared complexes have been used as new precursors for the preparation of the related nano-oxides. The crystallinity and morphology of the LnIII-oxide nano-particles were characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Self-assembly of ultra-thin lanthanide oxide nanowires via surfactant-mediated imperfect oriented attachment of nanoparticles

We report a simple synthesis of ultra-thin lanthanide oxide nanowires and ribbons via the autoclave-based decomposition of lanthanide oleates within passivating surfactants. Electron microscopy reveals the formation of linear self assemblies of lanthanide oxide nanoparticles that subsequently recrystallize into high aspect ratio materials via an “imperfect oriented attachment” mechanism.

Single-phased luminescent mesoporous nanoparticles for simultaneous cell imaging and anticancer drug delivery

Multifunctional materials for biological use have mostly been designed with composite or hybrid nanostructures in which two or more components are incorporated. The present work reports on a multifunctional biomaterial based on single-phased luminescent mesoporous lanthanide oxide nanoparticles that combine simultaneous drug delivery and cell imaging. A simple strategy based on solid-state-chemistry thermal decomposition process was employed to fabricate the spherical mesoporous Gd 2O 3:Eu nanoparticles with homogeneous size distribution. The porous nanoparticles developed by this strategy possess well-defined mesopores, large pore size and volume, and high specific surface area. The mesoporous features of nanoparticles impart the material with capabilities of loading and releasing the drug with a relatively high loading efficiency and a sustained release behavior of drugs. The DOX-loaded porous Gd 2O 3 nanoparticles are able to kill the cancer cells efficiently upon incubation with the human cervical carcinoma (HeLa) cells, indicating the potential for treatment of cancer cells. Meanwhile, the intrinsic luminescence of Gd 2O 3:Eu nanoparticles gives the function of optical imaging. Therefore, the drug release activity and effect of drugs on the cells can be effectively monitored via luminescence of nanoparticles themselves, realizing multifunctionality of simultaneous cell imaging and anticancer drug delivery in a single-phased nanoparticle.

NMR Transversal Relaxivity of Suspensions of Lanthanide Oxide Nanoparticles

Aqueous suspensions of paramagnetic lanthanide oxide nanoparticles have been studied by NMR relaxometry. The observed R * 2 relaxivities are explained by the static dephasing regime (SDR) theory. The corresponding R 2 relaxivities are considerably smaller and are strongly dependent on the interval between the two refocusing pulses. The experimental data are rationalized by assuming the value of the diffusion correlation time, τ D , to be very long in a layer with adsorbed xanthan on the particle's surface. In this layer, the refocusing pulses are fully effective and R 2 ≈ 0. Outside this layer, the diffusion model for weakly magnetized particles was applied. From the fit of the experimental relaxation data with this model, both the particle radii (r p ) and the radii of the spheres, within which the refocusing pulses are fully effective (r diff ), were estimated. The values of r p obtained are in agreement with those determined by dynamic light scattering. Because the value of r diff depends on the external magnetic field B and on the magnetic moment of the lanthanide of interest (μ eff 2 ), the R 2 relaxivity was found to be proportional to B and to μ eff 2 .

Isostructural neo-Pentoxide Derivatives of Group 3 and the Lanthanide Series Metals for the Production of Ln2O3 Nanoparticles

The synthesis and characterization of a series of neo-pentoxide (OCH2C(CH3)3 or ONep) derivatives of group 3 and the lanthanide (Ln) series' metals were undertaken via an amide/alcohol exchange route. Surprisingly, the products isolated and characterized by single-crystal X-ray diffraction yielded isostructural species for every trivalent cation studied: [Ln(mu-ONep)2(ONep)]4 [Ln=Sc (1), Y (2), La (3), Ce (4), Pr (5), Nd (6), Sm (7), Eu (8), Gd (9), Tb (10), Dy (11), Ho (12), Er (13), Tm (14), Yb (15), Lu (16)]. Compounds 3, 4, 6, and 11 have been previously reported. Within this series of complexes, the Ln metal centers are oriented in a square with each Ln-Ln edge interconnected via two mu-ONep ligands; each metal center also binds one terminal ONep ligand. NMR data of 1-3 indicate that the solid-state structure is retained in solution. FTIR spectroscopy (KBr pellet) revealed the presence of significant Ln---H-C interactions within one set of the bridging ONep ligands in all cases; the stretching frequencies of these C-H bonds appear to increase in magnitude with decrease in metal ion radius. These complexes were used to generate nanoparticles through solution hydrolysis routes, resulting in the formation of lanthanide oxide nanoparticles and rods. The emission properties of these ceramics were preliminarily investigated using UV-vis and PL measurements.

Synthesis and luminescent properties of PEO/lanthanide oxide nanoparticle hybrid films

In this study, we investigate the optical properties of lanthanide oxide nanoparticles dispersed in poly(ethylene oxide) (PEO) network as thermally stable polymeric films. The aim of this work is both to keep a good optical transparency in the visible domain and to obtain luminescent materials after incorporation of nanoparticles. For this purpose, we develop luminescent nanocrystals of oxides containing terbium ion as a doping element in Gd 2O 3. These sub-5-nm lanthanide oxides nanoparticles have been prepared by direct oxide precipitation in high-boiling polyalcohol solutions and characterized by luminescence spectroscopy. PEO/lanthanide oxide nanohybrid films are prepared by radical polymerization of poly(ethylene glycol) methacrylate after introduction of lanthanide oxide particles. As a first result; the obtained films present interesting luminescence properties with a very low lanthanide oxide content (up to 0.29 wt%). Furthermore, these films are still transparent and keep their original mechanical properties. Prior to describe the specific applications to optical use, we report here the dynamic mechanical analysis (DMA), X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), and luminescent properties of. nanohybrid films.

Eu3+-doped Gd2O3 nanoparticles as reporters for optical detection and visualization of antibodies patterned by microcontact printing

Lanthanide oxide nanoparticles are promising luminescent probes in bioanalysis, because of their unique spectral properties, photostability, and low-cost synthesis. We report for the first time the application of europium-doped gadolinium oxide (Eu:Gd2O3) nanoparticles to the optical imaging of antibody micropatterns. The nanoparticles were synthesized by spray pyrolysis and coated with antibody (IgG) molecules by physical adsorption. Our experiments showed that the Eu:Gd2O3 is a good biocompatible solid support for antibody immobilization. The antibodies (anti-rabbit IgG) immobilized on the nanoparticles had excellent biological activity in the specific recognition reaction with rabbit IgG patterned in line strips (10 micromx10 microm) on a glass substrate by use of a micro-contact printing technique. The specific immunoreaction was confirmed by two independent microscopic techniques-fluorescence and scanning electron microscopy (SEM). Both microscopic images revealed that the nanoparticles were organized into designated structures as defined by the microcontact printing process with negligible non-specific binding. The nanoparticles can be used as fluorescent markers in a variety of immunosensing applications in a microscale format.

Microarray Immunoassay for Phenoxybenzoic Acid Using Polymer Encapsulated Eu:Gd2O3Nanoparticles as Fluorescent Labels

Currently, detection in microarray bioanalysis is based mainly on the use of organic dyes. To overcome photobleaching and spectral overlaps we applied a new type of fluorophore, crystalline europium-doped gadolinium oxide (Eu:Gd2O3) nanoparticles, as labels in immunoassay microarrays. The Eu:Gd2O3 nanoparticles synthesized by spray pyrolysis offer narrow red emission, large Stokes shift, photostable laser-induced fluorescence with a long lifetime (1 ms). The amino functionalization of the particles was achieved by poly(L-lysine) (PL) encapsulation. The formation of a stable PL shell was confirmed by TEM analysis, colloidal stability studies, and quantification of the surface reactive amino groups. The PL-encapsulated particles were covalently conjugated to antibodies and successfully applied as reporters in a competitive fluorescence microimmunoassay for phenoxybenzoic acid (PBA), a generic biomarker of human exposure to pyrethroid insecticides. Microarrays were fabricated by microcontact printing of BSA-PBA in line patterns (10 x 10 microm). Confocal fluorescence microscopy combined with internal standard (fluorescein) calibration was used for quantitative measurements. The microarray immunoassay demonstrated a limit of detection of 1.4 microg L(-1) PBA. This work suggests the potential application of lanthanide oxide nanoparticles as fluorescent probes in microarray and biosensor technology, immunodiagnostics, and high-throughput screening.