Timur Sh. Atabaev

Color-tunable properties of Eu3+- and Dy3+-codoped Y2O3 phosphor particles.

Rare-earth phosphors are commonly used in display panels, security printing, and fluorescent lamps, and have potential applications in lasers and bioimaging. In the present study, Eu3+- and Dy3+-codoped uniform-shaped Y2O3 submicron particles were prepared using the urea homogeneous precipitation method. The structure and morphology of the resulting particles were characterized by X-ray diffraction, field emission scanning electron microscope, and field emission transmission electron microscope, whereas their optical properties were monitored by photoluminescence spectroscopy. The room-temperature luminescence color emission of the synthesized particles can be tuned from red to yellow by switching the excitation wavelength from 254 to 350 nm. The luminescence intensities of red and yellow emissions could be altered by varying the dopant concentration. Strong quenching was observed at high Eu3+ and Dy3+ concentrations in the Y2O3 host lattice.

Mesoporous silica with fibrous morphology: a multifunctional core–shell platform for biomedical applications

Multifunctional mesoporous silica nanocomposites are attractive carriers for targeted drug delivery in nanomedicine. Although promising developments have been made in the fabrication of multifunctional mesoporous silica nanocomposites, the design and mass production of novel multifunctional carriers are still challenging. This paper reports the facile one-pot fabrication of a multifunctional inorganic composite composed of superparamagnetic Fe3O4 nanoparticles and coated dye-functionalized mesoporous silica with a high specific surface area. The resulting composite particles had a tunable particle size, special open pore channels with high specific surface area, which is quite favorable for drug loading and release properties, as well as luminescent and superparamagnetic properties suitable for targeted drug delivery and tracking. This composite exhibited low toxicity, suggesting potential biomedical applications.

Submicron Y2O3 particles codoped with Eu and Tb ions: Size controlled synthesis and tuning the luminescence emission

Eu(3+) and Tb(3+) codoped Y(2)O(3) submicron particles were prepared using the simple urea homogeneous precipitation method. X-ray diffraction patterns revealed the synthesized particles to have a pure cubic Y(2)O(3) structure. Field-emission scanning electron microscopy and field-emission transmission electron microscopy showed that the synthesized particles had almost uniform spherical shapes. The luminescence color emission of the synthesized particles could be tuned from red due to the effective (5)D(0)→(7)F(j) (j=0, 1, 2 and 3) transitions within Eu(3+) to green due to the (5)D(4)→(7)F(5) transition within Tb(3+) by switching the excitation wavelength from 255 to 310 nm. Luminescence quenching was observed at high dopant concentrations. Strong and effective color-tunable emission is expected to find a wide range of applications in industry.

Facile synthesis of bifunctional silica-coated core–shell Y2O3:Eu3+,Co2+ composite particles for biomedical applications

In the present study, bifunctional silica-coated Y2O3:Eu3+,Co2+ spherical-shaped submicron composite particles were successfully prepared using a facile urea-assisted homogenous precipitation method. Synthesized Y2O3:Eu3+,Co2+ phosphor composites showed both ferromagnetic behaviour and strong visible red luminescence emission. The surface of the Y2O3:Eu3+,Co2+ phosphor composites was modified with a thin silica layer to enhance the luminescent properties and obtain higher biocompatibility of the samples. The composite particles with silica coatings resulted in a small decrease in the viability of L-929 fibroblastic cells at concentrations lower than 25 ppm and allowed cell imaging via internalization and wide distribution into the cells. Overall, these synthesized novel SiO2@Y2O3:Eu3+,Co2+ core–shell phosphor composites with both magnetic and luminescent properties have potential biomedical applications, including bioimaging and diagnosis, and can be also potentially used as MRI contrast agents.

Ultrafine PEG-capped gadolinia nanoparticles: cytotoxicity and potential biomedical applications for MRI and luminescent imaging

In recent years, magnetic and luminescent nanoparticles (NPs) have attracted considerable attention because of their potential applications in nanomedicine. In this study, bimodal ultrafine polyethylene glycol (PEG)-capped gadolinium oxide NPs doped with erbium ions, which combine both paramagnetic and luminescent properties in a single entity, were synthesized using the urea homogeneous precipitation route. The morphological, chemical and structural properties of the synthesized particles were examined using a range of microscopy and energy-dispersive X-ray techniques. The optical characteristics of the gadolinium oxide NPs were examined by analyzing the room temperature emission spectra, which correspond to various manifold transitions of Er3+. Pilot studies were performed to examine the cytotoxicity and capability of the synthesized NPs for the luminescent labeling of living C2C12 myoblastic cells. The paramagnetic properties of the synthesized particles as a magnetic resonance imaging MRI contrast agent were also assessed. Overall, these synthesized ultrafine PEG-coated Gd2O3:Er3+ NPs can potentially be used in biomedical applications because of their strong positive contrast enhancement in T1-weighted imaging, and intense green emission with near-infrared (NIR, 980 nm) excitation.

Fabrication of bifunctional core-shell Fe3O4 particles coated with ultrathin phosphor layer

Bifunctional monodispersed Fe3O4 particles coated with an ultrathin Y2O3:Tb3+ shell layer were fabricated using a facile urea-based homogeneous precipitation method. The obtained composite particles were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), quantum design vibrating sample magnetometry, and photoluminescence (PL) spectroscopy. TEM revealed uniform spherical core-shell-structured composites ranging in size from 306 to 330 nm with a shell thickness of approximately 25 nm. PL spectroscopy confirmed that the synthesized composites displayed a strong eye-visible green light emission. Magnetic measurements indicated that the composite particles obtained also exhibited strong superparamagnetic behavior at room temperature. Therefore, the inner Fe3O4 core and outer Y2O3:Tb3+ shell layer endow the composites with both robust magnetic properties and strong eye-visible luminescent properties. These composite materials have potential use in magnetic targeting and bioseparation, simultaneously coupled with luminescent imaging.

Cytotoxicity and cell imaging potentials of submicron color-tunable yttria particles†

Increased demand of environment protection encouraged scientists to design products and processes that minimize the use and generation of hazardous substances. This work presents comprehensive result of large-scale fabrication and investigation of red-to-green tunable submicron spherical yttria particles codoped with low concentrations of Eu(+3) and Tb(+3). The color emission of synthesized particles can be precisely tuned from red to green by simple variation of Tb/Eu ratio and excitation wavelength. The Tb/Eu-codoped Y(2)O(3) particles did not adversely affect the viability of L-929 fibroblastic cells at concentrations less than 62.5 ppm. Through internalization and wide distribution inside the cells, Tb/Eu codoped Y(2)O(3) particles with intense bright green or red fluorescence rendered cell imaging to be possible. The high brightness, excellent stability, low-toxicity, and imaging capability along with fine color-tunability of synthesized particles enable to find promising application in various areas.

Facile hydrothermal synthesis of flower-like hematite microstructure with high photocatalytic properties

A flower-like hematite microstructure has been successfully prepared by a facile hydrothermal synthesis method without using any organic solvents or templates. It is revealed that the flower-like hematite microstructure consists of well-crystallized nanorods with the average diameter of about 100±15 nm and average length of about 900±100 nm growing from the centers. A possible growth mechanism of the flower-like α-Fe2O3 microstructure is proposed and discussed. The photocatalytic properties of the synthesized flower-like hematite nanostructure are evaluated using the degradation of rhodamine B in aqueous solution.

Highly Mesoporous Silica Nanoparticles for Potential Drug Delivery Applications

There is an increasing interest in the use of silica nanoparticles (NPs) for bioapplications. Highly mesoporous fluorescein dye-doped silica NPs that can carry a drug payload have been successfully synthesized through a facile microemulsion process. The morphology of the as-prepared silica NPs were characterized by scanning electron microscope and transmission electron microscope, whereas their optical properties were studied by photoluminescence spectroscopy. The results revealed that these silica NPs exhibit excellent properties, including large pore volume, a narrow size distribution and strong fluorescent properties. The synthesized silica NPs showed a good biocompatibility and a low cytotoxicity when incubated in a murine fibroblast L-929 cell line. The obtained silica NPs were further used as drug delivery carriers to investigate the in vitro drug release properties using doxorubicin (DOX) as a representative drug model. It was shown that synthesized silica NPs well sustained drug release properties, suggesting their potential applications for drug delivery.

Luminescent core–shell Fe3O4@Gd2O3:Er3+, Li+ composite particles with enhanced optical properties

Abstract Bifunctional magneto-optical nanocomposites with Fe3O4 nanoparticles as a core and erbium and lithium codoped gadolinium (Gd2O3:Er3+, Li+) as the shell were synthesized successfully using a simple urea homogeneous precipitation method. The fabricated Fe3O4@Gd2O3:Er3+, Li+ particles were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy and quantum design vibrating sample magnetometry. The upconversion emission intensity was enhanced significantly comparing to that without Li+ ions. These bifunctional composites are expected to be potentially applied for drug delivery, cell separation and bioimaging.