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1.
J Fluoresc ; 29(2): 435-443, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30685830

RESUMO

A multicolor tunable CaWO4:xDy3+ nanophosphors have been synthesized via hydrothermal route. X-Ray Diffraction and Fourier transform infrared confirm the formation of CaWO4:Dy3+ nanophosphors. Transmission electron microscopy image and selected area electron diffraction (SAED) reveal the formation of nanosize and crystalline CaWO4:Dy3+. Dependence of energy transfer rate from WO42- to the activator (Dy3+) is observed from the photoluminescence studies. An enhancement of energy transfer efficiency from 36% to 90% is observed after annealing the as-prepared samples at 800 °C. The exchange type energy transfer mechanism is observed to be dominant in as-prepared samples while the electric dipole-dipole interaction is dominant in annealed samples. Variation in energy transfer rate from the host to Dy3+ activator ions leads to the tuning of color emission from this nanophosphor. A near white light emission could be achieved with 6 at.% Dy3+ doped CaWO4 annealed at 800 °C with x = 0.310 and y = 0.327.

2.
Nanotechnology ; 24(6): 065101, 2013 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-23324398

RESUMO

Polyol mediated synthesized luminescent YVO(4):Eu(3+) nanoparticles (NPs) have been encapsulated in mesoporous silica nanoparticles (MSNs) using the sol-gel process. X-ray diffraction and Fourier transform infrared spectroscopy along with transmission electron microscopy confirm the encapsulation of the YVO(4):Eu(3+) NPs in the SiO(2) matrix. N(2) adsorption/desorption analysis confirms the mesoporous nature of the MSNs and YVO(4):Eu(3+)-MSNs. No significant quenching of the YVO(4):Eu(3+) luminescence is observed for YVO(4):Eu(3+)-MSNs. This nanocomposite has been tested as a potential drug carrier. Efficient loading of doxorubicin hydrochloride (DOX), a typical anticancer drug, is observed which reaches up to 93% in 8 mg ml(-1) of YVO(4):Eu(3+)-MSNs. pH sensitive release of DOX is observed, with 54% release for pH 4.3 and 31% in a physiological environment (pH 7.4). Both MSNs and YVO(4):Eu(3+)-MSNs nanocomposites do not show accountable toxicity to two cell lines, i.e. HeLa and MCF-7. However, as desired, toxicity is observed when cells are incubated with DOX loaded YVO(4):Eu(3+)-MSNs. Laser scanning confocal microscopy images confirm the uptake of the nanocomposite in both cell lines. The morphology of the cells (MCF-7) changes after incubation with DOX loaded YVO(4):Eu(3+)-MSNs, indicating an interaction of DOX with the cells. More cytotoxicity to both cell lines with ∼90% killing is observed due to the synergistic effect of magnetic fluid hyperthermia and chemotherapy using a biphasic suspension of superparamagnetic iron oxide magnetic nanoparticles and DOX loaded YVO(4):Eu(3+)-MSNs. In addition, an AC magnetic field triggers an enhanced drug release.


Assuntos
Antibióticos Antineoplásicos/administração & dosagem , Doxorrubicina/administração & dosagem , Nanopartículas/uso terapêutico , Neoplasias/diagnóstico , Neoplasias/terapia , Antibióticos Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Doxorrubicina/farmacologia , Portadores de Fármacos/química , Portadores de Fármacos/uso terapêutico , Portadores de Fármacos/toxicidade , Európio/química , Európio/uso terapêutico , Európio/toxicidade , Óxido Ferroso-Férrico/química , Óxido Ferroso-Férrico/uso terapêutico , Óxido Ferroso-Férrico/toxicidade , Humanos , Hipertermia Induzida/métodos , Magnetismo/métodos , Nanopartículas/química , Nanopartículas/toxicidade , Dióxido de Silício/química , Dióxido de Silício/uso terapêutico , Dióxido de Silício/toxicidade , Vanadatos/química , Vanadatos/uso terapêutico , Vanadatos/toxicidade , Ítrio/química , Ítrio/uso terapêutico , Ítrio/toxicidade
3.
Dalton Trans ; 41(15): 4404-12, 2012 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-22334276

RESUMO

GdVO(4) : Ln(3+) (Ln(3+) = Dy(3+), Eu(3+), Sm(3+), Tm(3+)) nanoparticles are prepared by a simple chemical route at 140 °C. The crystallite size can be tuned by varying the pH of the reaction medium. Interestingly, the crystallite size is found to increase significantly when pH increases from 6 to 12. This is related to slower nucleation of the GdVO(4) formation with increase of VO(4)(3-) present in solution. The luminescence study shows an efficient energy transfer from vanadate absorption of GdVO(4) to Ln(3+) and thereby enhanced emissions are obtained. A possible reaction mechanism at different pH values is suggested in this study. As-prepared samples are well dispersed in ethanol, methanol and water, and can be incorporated into polymer films. Luminescence and its decay lifetime studies confirm the decrease in non-radiative transition probability with the increase of heat treatment temperature. Re-dispersed particles will be useful in potential applications of life science and the film will be useful in display devices.

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