RESUMEN
The Ti3C2 MXene quantum dots (Ti3C2 MQDs) derived from Ti3C2 MXene have received much attention because of their remarkable advantages in biosensing. Nevertheless, the functionalization of Ti3C2 MQDs to improve their properties is just in its infant stage. Herein, we firstly synthesized nitrogen and boron co-doped Ti3C2 MQDs (N, B-Ti3C2 MQDs) with good water solubility, strong stability, and high optical characteristics. The N, B-Ti3C2 MQDs exhibit excitation wavelength-dependent blue photoluminescence with optimal excitation/emission peaks at 335/439 nm. Nowadays, the development of fast and real-time detection of tetracycline (TC) in animal derived food is very essential. In this work, a novel point-of-care testing (POCT) platform was established based on ratiometric fluorescence method using N, B-Ti3C2 MQDs coupled with Eu3+. Upon addition of TC in the Eu3+/N, B-MQDs system, blue fluorescence emission of N, B-Ti3C2 MQDs was quenched and red fluorescence emission of Eu3+ was enhanced gradually, which was ascribed to the synergistic inner filter effect and antenna effect. Moreover, we prepared test papers with N, B-Ti3C2 MQDs and Eu3+ for TC detection based on the change of fluorescence color, which could be recognized by color recognizer app installed in the smartphone. Therefore, great promise for POCT of TC is given with the merits of simplicity and visible detection possibility. The proposed method demonstrated a low detection limit of 20 nM. Application of the platform for TC quantification in milk samples opened a novel means for the potential use of N, B-Ti3C2 MQDs in food safety.
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Europio/química , Colorantes Fluorescentes/química , Pruebas en el Punto de Atención , Puntos Cuánticos/química , Tetraciclina/análisis , Titanio/química , Animales , Antibacterianos/análisis , Boro/química , Boro/efectos de la radiación , Europio/efectos de la radiación , Fluorescencia , Colorantes Fluorescentes/efectos de la radiación , Contaminación de Alimentos/análisis , Límite de Detección , Leche/química , Nitrógeno/química , Nitrógeno/efectos de la radiación , Papel , Puntos Cuánticos/efectos de la radiación , Teléfono Inteligente , Espectrometría de Fluorescencia/instrumentación , Espectrometría de Fluorescencia/métodos , Titanio/efectos de la radiación , Rayos UltravioletaRESUMEN
A series of fluorescent nanocomplexes of carboxymethyl cellulose (CMC)/Terbium (Tb)- Europium (Eu) were successfully synthesized without introducing a second ligand. By adjusting the concentration of the coordinated ions, these nanocomplexes exhibit favorably visibly tunable luminescence properties with colors being able to change from green to red. The XPS analysis demonstrates the formation Tb(III)-O2- and Eu(III)-O2- between OH and COO- in CMC and Tb3+ or Eu3+ ions, which is advantage for light absorption by UV-Vis spectroscopy and fluorescence spectroscopy. The ligand CMC plays a role in coordinating with terbium and europium ions, but also serves as an energy donor to these metal ions by antenna effect. Moreover, the energy transfer also occurred from terbium ions to europium ions in CMC matrix, which is responsible for the tunable luminescence properties of these complexes.
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Complejos de Coordinación/química , Sustancias Luminiscentes/química , Nanoestructuras/química , Carboximetilcelulosa de Sodio/química , Complejos de Coordinación/efectos de la radiación , Transferencia de Energía , Europio/química , Europio/efectos de la radiación , Ligandos , Luz , Luminiscencia , Sustancias Luminiscentes/efectos de la radiación , Nanoestructuras/efectos de la radiación , Terbio/química , Terbio/efectos de la radiaciónRESUMEN
A near-infrared light-activated ratiometric photoelectrochemical aptasensor was fabricated for detection of carcinoembryonic antigen (CEA) coupling with upconversion nanoparticles (UCNPs)-semiconductor nanocrystals-based spatial-resolved technique on a homemade 3D printing device in which a self-regulating integrated electrode was designed for dual signal readout. The as-prepared NaYF4:Yb,Er UCNPs@CdTe nanocrystals were initially assembled on two adjacent photoelectrodes, then CEA aptamer 1 (A1) and capture DNA (CA) were modified onto two working photoelectrodes (WP1 and WP2) through covalent binding, respectively, and then gold nanoparticle-labeled CEA aptamer 2 (Au NP-A2) was immobilized on the surface of functional WP2 for the formation of double-stranded DNA. Upon target CEA introduction, the various concentrations of CEA were captured on the WP1, whereas the binding of the CEA with Au NP-A2 could be released from the WP2 thanks to the highly affinity of CEA toward A2. The dual signal readout with the "signal-off" of WP1 and "signal-on" of WP2 were employed for the spatial-resolved PEC (SR-PEC) strategy to detect CEA as an analytical model. Combining NaYF4:Yb,Er UCNPs@CdTe nanocrystals with spatial-resolved model on 3D printing device, the PEC ratiometric aptasensor based on steric hindrance effect and exciton-plasmon interactions (EPI) exhibited a linear range from 10.0 pg mL-1 to 5.0 ng mL-1 with a limit of detection of 4.8 pg mL-1 under 980 nm illumination. The SR-PEC ratiometric strategy showed acceptable stability and reproducibility with a superior anti-interference ability. This approach can provide the guidance for the design of ratiometric, multiplexed, and point-of-care biosensors.
Asunto(s)
Aptámeros de Nucleótidos/química , Técnicas Biosensibles/métodos , Antígeno Carcinoembrionario/análisis , Puntos Cuánticos/química , Aptámeros de Nucleótidos/genética , Técnicas Biosensibles/instrumentación , Compuestos de Cadmio/química , Compuestos de Cadmio/efectos de la radiación , Antígeno Carcinoembrionario/química , ADN/química , ADN/genética , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Electrodos , Europio/química , Europio/efectos de la radiación , Fluoruros/química , Fluoruros/efectos de la radiación , Oro/química , Rayos Infrarrojos , Límite de Detección , Nanopartículas del Metal/química , Hibridación de Ácido Nucleico , Impresión Tridimensional , Puntos Cuánticos/efectos de la radiación , Telurio/química , Telurio/efectos de la radiación , Itrio/química , Itrio/efectos de la radiaciónRESUMEN
Two highly luminescent and water-soluble Eu(III) complexes, Eu1 and Eu2, based on novel carboxyl-functionalized 1,5-naphthyridine derivatives 8-hydroxy-1,5-naphthyridine-2-carboxylic acid (H2L1) and 7-cyano-8-hydroxy-1,5-naphthyridine-2-carboxylic acid (H2L2), respectively, are designed and synthesized. The crystal structure of Eu2 indicates that the central Eu(III) ion is nine-coordinated by three tridentate ligands (O^N^O). Both Eu1 and Eu2 show strong luminescence in aqueous solution with quantum yields (lifetimes) of 28% (1.1 ms) and 14% (0.76 ms), respectively. The chelates display unique UV-light stability in solution and remain highly emissive after 100 min of strong UV irradiation (â¼300 W·m-2 at 345 nm). Moreover, they exhibit reversible luminescence intensity changes with varied pH values, and the response mechanism is investigated. "Turn-on" of the Eu(III) emission upon increasing pH is realized by ligand structure change from keto to enol anion form, resulting in red-shifted absorption band and suppressed quenching from solvents and N-H vibration upon deprotonating. The results show that these novel Eu(III) complexes are quite intriguing for potential application as bioimaging agents and pH probes.
Asunto(s)
Complejos de Coordinación/efectos de la radiación , Europio/efectos de la radiación , Naftiridinas/efectos de la radiación , Complejos de Coordinación/síntesis química , Complejos de Coordinación/química , Europio/química , Concentración de Iones de Hidrógeno , Ligandos , Luminiscencia , Naftiridinas/síntesis química , Naftiridinas/química , Fotoblanqueo , Solubilidad , Rayos Ultravioleta , Agua/químicaRESUMEN
This paper reports the thermoluminescence properties of Eu(3+) doped different host matrix phosphors (SrY2O4 and Y4Al2O9). The phosphor is prepared by high temperature solid state reaction method. The method is suitable for large scale production and fixed concentration of boric acid using as a flux. The prepared samples were characterized by X-ray diffraction technique and the crystallite size calculated by Scherer's formula. The prepared phosphor characterized by Scanning Electron Microscopic (SEM), Fourier Transform Infrared (FTIR), Energy Dispersive X-ray analysis (EDX), thermoluminescence (TL) and Transmission Electron Microscopic (TEM) techniques. The prepared phosphors for different concentration of Eu(3+) ions were examined by TL glow curve for UV, beta and gamma irradiation. The UV 254nm source used for UV irradiation, Sr(90) source was used for beta irradiation and Co(60) source used for gamma irradiation. SrY2O4:Eu(3+)and Y4Al2O9:Eu(3+) phosphors which shows both higher temperature peaks and lower temperature peaks for UV, beta and gamma irradiation. Here UV irradiated sample shows the formation of shallow trap (surface trapping) and the gamma irradiated sample shows the formation of deep trapping. The estimation of trap formation was evaluated by knowledge of trapping parameters. The trapping parameters such as activation energy, order of kinetics and frequency factor were calculated by peak shape method. Here most of the peak shows second order of kinetics. The effect of gamma, beta and UV exposure on TL studies was also examined and it shows linear response with dose which indicate that the samples may be useful for TL dosimetry. Formation of deep trapping mechanism by UV, beta and gamma irradiated Eu(3+) activated SrY2O4 and Y4Al2O9 phosphors is discussed in this paper.
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Europio/química , Europio/efectos de la radiación , Luminiscencia , Óxido de Aluminio , Partículas beta , Rayos gamma , Cinética , Mediciones Luminiscentes , Microscopía Electrónica de Rastreo , Espectrometría por Rayos X , Espectroscopía Infrarroja por Transformada de Fourier , Estroncio , Dosimetría Termoluminiscente , Rayos Ultravioleta , Difracción de Rayos X , ItrioRESUMEN
A water-soluble light-responsive antitumor agent, PtEuL, based on a cisplatin-linked europium-cyclen complex has been synthesized and evaluated for controlled cisplatin release by linear/two-photon excitation in vitro with concomitant turn-on and long-lived europium emission as a responsive traceable signal.
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Antineoplásicos/química , Cisplatino/química , Complejos de Coordinación/química , Monitoreo de Drogas/métodos , Europio/química , Sustancias Luminiscentes/química , Rayos Ultravioleta , Antineoplásicos/farmacocinética , Antineoplásicos/farmacología , Antineoplásicos/efectos de la radiación , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Dicroismo Circular , Cisplatino/farmacocinética , Cisplatino/farmacología , Cisplatino/efectos de la radiación , Complejos de Coordinación/efectos de la radiación , Preparaciones de Acción Retardada , Sistemas de Liberación de Medicamentos/métodos , Liberación de Fármacos , Europio/efectos de la radiación , Humanos , Sustancias Luminiscentes/efectos de la radiación , Mediciones Luminiscentes/métodos , FotonesRESUMEN
The investigation of scintillation properties of europium doped yttrium orthovanadate shows the suitability of this material for fiber-based dose rate measurements. All measurements were carried out with a 6 MV Varian linear accelerator. The temperature dependence of the signal is lower than that of the plastic scintillators reported so far. By measuring the afterglow of probes between Linac-pulses, the signal due to the stem effect can be successfully eliminated. Comparison of depth dose profiles in a water phantom for radiation field dimensions between 1 x 1 cm(2) and 10 x 10 cm(2) shows that the probes are suitable for small fields having dimensions up to 1 x 1 cm(2). The high light yield of probes having dimensions of 1 mm opens up the possibility for their use in spatially confined radiation fields, such as in intensity-modulated radiotherapy (IMRT) and volume-modulated radiation therapy (VMAT).
Asunto(s)
Europio/efectos de la radiación , Tecnología de Fibra Óptica/instrumentación , Fotones , Radioterapia Conformacional/métodos , Conteo por Cintilación/instrumentación , Itrio/efectos de la radiación , Relación Dosis-Respuesta en la Radiación , Diseño de Equipo , Análisis de Falla de Equipo , Europio/química , Tecnología de Fibra Óptica/métodos , Ensayo de Materiales , Aceleradores de Partículas , Polvos , Dosis de Radiación , Conteo por Cintilación/métodos , Vanadatos , Itrio/químicaRESUMEN
A new silver(I)-alkynyl cluster with a [Eu(W5O18)2](9-) polyoxoanionic core of [Ag42{Eu(W5O18)2}((t)BuC≡C)28Cl4] [OH]·H2O (1) has been designed and synthesized. The [Eu(W5O18)2](9-) polyoxoanion acts as a template to induce the formation of the surrounding 42-core Ag(I) cage. Due to the hydrophobic silver(I)-alkynyl shell, 1 features an unusual fluorescence enhancement as compared to the precursor of the [Eu(W5O18)2](9-) polyoxoanionic core. Interestingly, the silver ions in the shell silver(I)-alkynyl cage can only be reduced to silver atoms by irradiation with high energy UV light (2 kW). Upon high UV irradiation, fluorescence quenching of 1 has been observed. Moreover, the solution fluorescence of 1 can be modulated by addition of S(2-) ions into the system, which also leads to the fluorescence quenching phenomenon. The successful synthesis of 1 demonstrates a new route to the detection of high energy UV irradiation or S(2-) ions by elaborate design of fluorescence quenching of silver(I)-alkynyl clusters.
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Europio/química , Plata/química , Compuestos de Tungsteno/química , Europio/efectos de la radiación , Fluorescencia , Plata/efectos de la radiación , Compuestos de Tungsteno/efectos de la radiación , Rayos UltravioletaRESUMEN
Eu-B co-doped BiVO4 visible-light-driven photocatalysts have been synthesized using the sol-gel method. The resulting materials were characterized by a series of joint techniques, including XPS, XRD, SEM, BET, and UV-vis DRS analyses. Compared with BiVO4 and B-BiVO4 photocatalysts, the Eu-B-BiVO4 photocatalysts exhibited much higher photocatalytic activity for methyl orange (MO) degradation under visible light irradiation. The optimal Eu doping content is 0.8 mol%. It was revealed that boron and europium were doped into the lattice of BiVO4 and this led to more surface oxygen vacancies, high specific surface areas, small crystallite size, a narrower band gap and intense light absorbance in the visible region. The doped Eu(III) cations can help in the separation of photogenerated electrons. The synergistic effects of boron and europium in doped BiVO4 were the main reason for improving visible light photocatalytic activity.
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Compuestos Azo/química , Bismuto/química , Boro/química , Europio/química , Nanopartículas/química , Vanadatos/química , Contaminantes Químicos del Agua/química , Bismuto/efectos de la radiación , Boro/efectos de la radiación , Europio/efectos de la radiación , Luz , Microscopía Electrónica de Rastreo , Nanopartículas/efectos de la radiación , Nanopartículas/ultraestructura , Fotólisis , Vanadatos/efectos de la radiaciónRESUMEN
The ZnO short nanorods and flowerlike nanostructures doped with Eu3+ ions are prepared by a hydrothermal method through adjusting the hydrothermal temperature. The XRD, FESEM, FT-IR, luminescent and photocatalytic properties are characterized. The results indicate that the hydrothermal temperature affects the morphology of ZnO:Eu3+ nanocrystals, short nanorods at 120 degrees C, flowerlike nanocrystals at 150 degrees C and nanoparticles at 180 degrees C. The structures of ZnO:Eu3+ nanocrystals prepared at different hydrothermal temperatures are assigned to hexagonal phase. The photoluminescent properties including excitation and emission spectra are studied. The charge transfer band and f-f transition absorption are observed in excitation spectra. And, the 5D(0)-7F(J) (J = 0-4) transition emissions appear in emission spectra. In addition, the photocatalytic properties are also studied. The degradation rate of ZnO:Eu3+ nanocrystals is a little lower than pure ZnO nanocrystals.
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Europio/química , Mediciones Luminiscentes/métodos , Nanoestructuras/química , Nanoestructuras/ultraestructura , Óxido de Zinc/química , Catálisis , Europio/efectos de la radiación , Luz , Ensayo de Materiales , Nanoestructuras/efectos de la radiación , Tamaño de la Partícula , Óxido de Zinc/efectos de la radiaciónRESUMEN
In this paper, pure and Eu3+ doped TiO2 nanocrystals (NCs) have been fabricated successfully by a two steps of sol-gel and hydrothermal methods. The microstructures, morphologies and photoluminescent properties of Eu(3+)-TiO2 were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and photoluminescence spectroscopy (PL). XRD and PL results show that the existent of rare earth can inhibit the transformation of TiO2 NCs from anatase to rutile phase and can improve the luminescence intensity of the prepared samples. The room-temperature PL emission of the as-grown samples is dominated by the 5D(0)-7F(j) transitions of Eu3+ ions. But the luminescence intensity drops dramatically when the annealing temperature reaches a relatively high degree because of the formation of the rutile phase of TiO2 NCs hosts.
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Cristalización/métodos , Europio/química , Mediciones Luminiscentes/métodos , Nanoestructuras/química , Nanoestructuras/ultraestructura , Titanio/química , Europio/efectos de la radiación , Iones , Luz , Ensayo de Materiales , Nanoestructuras/efectos de la radiación , Tamaño de la Partícula , Titanio/efectos de la radiaciónRESUMEN
We report that Eu(2+) can be an efficient sensitizer for Yb(3+) and a broadband absorber for blue solar spectra in the host of oxide glass. The greenish 4f â 5d transition of Eu(2+) and the characteristic near-infrared emission of Yb(3+) were observed, with the blue-light of xenon lamp excitation. The 5d energy can be adjusted by the host and the energy transfer efficiency can be enhanced. The quantum efficiency is up to 163.8%. Given the broad excitation band, high absorption coefficient and excellent mechanical, thermal and chemical stability, this system can be useful as down-conversion layer for solar cells.
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Europio/química , Vidrio/química , Óxidos/química , Refractometría/métodos , Iterbio/química , Absorción/efectos de la radiación , Europio/efectos de la radiación , Vidrio/efectos de la radiación , Luz , Ensayo de Materiales , Óxidos/efectos de la radiación , Iterbio/efectos de la radiaciónRESUMEN
Biocompatible nanoparticles possessing fluorescent properties offer attractive possibilities for multifunctional bioimaging and/or drug and gene delivery applications. Many of the limitations with current imaging systems center on the properties of the optical probes in relation to equipment technical capabilities. Here we introduce a novel high aspect ratio and highly crystalline europium-doped calcium phosphate nanowhisker produced using a simple microwave-assisted solution combustion synthesis method for use as a multifunctional bioimaging probe. X-ray diffraction confirmed the material phase as europium-doped hydroxyapatite. Fluorescence emission and excitation spectra and their corresponding peaks were identified using spectrofluorimetry and validated with fluorescence, confocal and multiphoton microscopy. The nanowhiskers were found to exhibit red and far red wavelength fluorescence under ultraviolet excitation with an optimal peak emission of 696 nm achieved with a 350 nm excitation. Relatively narrow emission bands were observed, which may permit their use in multicolor imaging applications. Confocal and multiphoton microscopy confirmed that the nanoparticles provide sufficient intensity to be utilized in imaging applications.
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Fosfatos de Calcio/síntesis química , Cristalización/métodos , Europio/química , Microscopía de Fluorescencia por Excitación Multifotónica/métodos , Nanopartículas/química , Fosfatos de Calcio/efectos de la radiación , Medios de Contraste/síntesis química , Medios de Contraste/efectos de la radiación , Europio/efectos de la radiación , Calor , Ensayo de Materiales , Microondas , Nanopartículas/ultraestructura , Tamaño de la Partícula , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
By using a visible-light-excited ternary Eu(3+) complex, BHHBCB-Eu(3+)-BPT (BHHBCB: 1,2-bis[4'-(1",1",1",2",2",3",3"-heptafluoro-4â³,6â³-hexanedion-6â³-yl)-benzyl]-4-chlorosulfobenzene; BPT: 2-(N,N-diethylanilin-4-yl)-4,6-bis(pyrazol-1-yl)-1,3,5-triazine), as a luminophore, two kinds of novel visible-light-excited europium materials, the silica-encapsulated BHHBCB-Eu(3+)-BPT (Eu@SiO2) nanoparticles and BHHBCB-Eu(3+)-BPT-conjugated bovine serum albumin (BSA-BHHBCB-Eu(3+)-BPT), were prepared for biolabeling and time-resolved luminescence cell imaging applications. The Eu@SiO2 nanoparticles, prepared by the copolymerization of 3-aminopropyl(triethoxy)silane-BHHBCB-Eu(3+)-BPT conjugate, free 3-aminopropyl(triethoxy) silane and tetraethyl orthosilicate in a water-in-oil reverse microemulsion, are monodispersed, spherical and uniform in size, and strongly luminescent with an excitation peak at ≈ 400 nm and a long luminescence lifetime of 346 µs. The BSA-BHHBCB-Eu(3+)-BPT, prepared by covalent binding of BHHBCB-Eu(3+)-BPT to BSA, shows also strong visible-light-excited luminescence with a excitation peak at ≈ 400 nm and a long luminescence lifetime of 402µs. The two materials were used for labeling transferrin and folic acid. Using the time-resolved luminescence imaging of living HeLa cells, the cell-surface receptors of transferrin and folic acid were successfully visualized by the prepared biolabels based on the ligand-receptor affinity binding interaction. The results demonstrated the feasibility of the new materials as visible-light-excited biolabels for the time-resolved luminescence cell imaging.
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Europio/química , Nanopartículas/química , Albúmina Sérica Bovina/química , Dióxido de Silicio/química , Diagnóstico por Imagen , Europio/efectos de la radiación , Ácido Fólico/química , Células HeLa , Humanos , Luz , Luminiscencia , Microscopía Electrónica de Transmisión , Nanopartículas/efectos de la radiación , Nanopartículas/ultraestructura , Albúmina Sérica Bovina/efectos de la radiación , Dióxido de Silicio/efectos de la radiación , Transferrina/químicaRESUMEN
The anisotropic emission properties of an Eu(III)-MWCNTs-based nanocomposite PNIPAAm hydrogel is induced upon application of a 10 T magnetic field, the latter dictating the alignment of the carbon nanotubes. This structuration creates directional highways for light to be preferentially absorbed, giving rise to orientation-dependent light emission intensity. Thermal control of the transparency of the aqueous matrix also allowed a stimulus-induced switching of the materials' emission properties.
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Resinas Acrílicas/química , Europio/química , Mediciones Luminiscentes/métodos , Nanotubos de Carbono/química , Nanotubos de Carbono/efectos de la radiación , Anisotropía , Europio/efectos de la radiación , Campos Magnéticos , Ensayo de Materiales , Conformación Molecular/efectos de la radiación , Nanotubos de Carbono/ultraestructura , Tamaño de la Partícula , Propiedades de SuperficieRESUMEN
PURPOSE: An important property of a reusable dosimeter is its radiation hardness, that is, its ability to retain its dosimetric merits after irradiation. The radiation hardness of europium doped potassium chloride (KC1:Eu2+), a storage phosphor material recently proposed for radiation therapy dosimetry, is examined in this study. METHODS: Pellet-style KCl:Eu2+ dosimeters, 6 mm in diameter, and 1 mm thick, were fabricated in-house for this study. The pellets were exposed by a 6 MV photon beam or in a high dose rate 137Cs irradiator. Macroscopic properties, such as radiation sensitivity, dose response linearity, and signal stability, were studied with a laboratory photostimulated luminescence (PSL) readout system. Since phosphor performance is related to the state of the storage centers and the activator, Eu2+, in the host lattice, spectroscopic and temporal measurements were carried out in order to explore radiation-induced changes at the microscopic level. RESULTS: KCl:Eu2+ dosimeters retained approximately 90% of their initial signal strength after a 5000 Gy dose history. Dose response was initially supralinear over the dose range of 100-700 cGy but became linear after 60 Gy. Linearity did not change significantly in the 0-5000 Gy dose history spanned in this study. Annealing high dose history chips resulted in a return of supralinearity and a recovery of sensitivity. There were no significant changes in the PSL stimulation spectra, PSL emission spectra, photoluminescence spectra, or luminescence lifetime, indicating that the PSL signal process remains intact after irradiation but at a reduced efficiency due to reparable radiation-induced perturbations in the crystal lattice. CONCLUSIONS: Systematic studies of KCl:Eu2+ material are important for understanding how the material can be optimized for radiation therapy dosimetry purposes. The data presented here indicate that KCl:Eu2+ exhibits strong radiation hardness and lends support for further investigations of this novel material.
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Europio , Cloruro de Potasio , Radiometría/métodos , Relación Dosis-Respuesta en la Radiación , Equipo Reutilizado , Europio/efectos de la radiación , Humanos , Luminiscencia , Fantasmas de Imagen , Cloruro de Potasio/efectos de la radiación , Radiometría/estadística & datos numéricos , Planificación de la Radioterapia Asistida por Computador/estadística & datos numéricos , Radioterapia de Intensidad ModuladaRESUMEN
PURPOSE: The low effective atomic number, reusability, and other computed radiography-related advantages make europium doped potassium chloride (KCl : Eu2+) a promising dosimetry material. The purpose of this study is to model KCl : Eu2+ point dosimeters with a Monte Carlo (MC) method and, using this model, to investigate the dose responses of two-dimensional (2D) KCl : Eu2+ storage phosphor films (SPFs). METHODS: KCl : Eu2+ point dosimeters were irradiated using a 6 MV beam at four depths (5-20 cm) for each of five square field sizes (5 x 5-25 x 25 cm2). The dose measured by KCl : Eu2+ was compared to that measured by an ionization chamber to obtain the magnitude of energy dependent dose measurement artifact. The measurements were simulated using DOSXYZnrc with phase space files generated by BEAMnrcMP. Simulations were also performed for KCl : Eu2+ films with thicknesses ranging from 1 microm to 1 mm. The work function of the prototype KCl : Eu2+ material was determined by comparing the sensitivity of a 150 microm thick KCl : Eu2+ film to a commercial BaFBr0.85 I0.15 : Eu(2+)-based SPF with a known work function. The work function was then used to estimate the sensitivity of a 1 microm thick KCl : Eu2+ film. RESULTS: The simulated dose responses of prototype KCl : Eu2+ point dosimeters agree well with measurement data acquired by irradiating the dosimeters in the 6 MV beam with varying field size and depth. Furthermore, simulations with films demonstrate that an ultrathin KCl : Eu2+ film with thickness of the order of 1 microm would have nearly water-equivalent dose response. The simulation results can be understood using classic cavity theories. Finally, preliminary experiments and theoretical calculations show that ultrathin KCl : Eu2+ film could provide excellent signal in a 1 cGy dose-to-water irradiation. CONCLUSIONS: In conclusion, the authors demonstrate that KCl : Eu(2+)-based dosimeters can be accurately modeled by a MC method and that 2D KCl : Eu2+ films of the order of 1 microm thick would have minimal energy dependence. The data support the future research and development of a KCl : Eu2+ storage phosphor-based system for quantitative, high-resolution multidimensional radiation therapy dosimetry.
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Europio/química , Europio/efectos de la radiación , Modelos Químicos , Cloruro de Potasio/química , Cloruro de Potasio/efectos de la radiación , Radiometría/instrumentación , Radioterapia Conformacional/métodos , Simulación por Computador , Diseño Asistido por Computadora , Relación Dosis-Respuesta en la Radiación , Diseño de Equipo , Análisis de Falla de Equipo , Ensayo de Materiales , Dosificación Radioterapéutica , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Agua/químicaRESUMEN
Europium (Eu)-doped silicon oxide films with Eu concentrations from 2.1 to 4.7 at. % were deposited by electron beam evaporation. The Eu related luminescence from the films was found to be sensitive to the evolution of film microstructures at different annealing temperatures. Luminescence centers in the films changed from defects of silicon oxides to 4f(6)5d-4f(7)(8S(7/2)) transition of Eu2+ after the films annealed in N2 at temperature higher than 800 °C. The evolution of luminescence centers was attributed to the formation of europium silicate (EuSiO3), which was confirmed by x-ray photoelectron spectroscopy, x-ray diffraction, time resolved photoluminescence, and transmission electron microscopy.
Asunto(s)
Europio/química , Rayos Láser , Luminiscencia , Membranas Artificiales , Dióxido de Silicio/química , Europio/efectos de la radiaciónRESUMEN
In medical mammographic imaging systems, one type of detector configuration, often referred to as indirect detectors, is based on a scintillator layer (phosphor screen) that converts the x-ray radiation into optical signal. The indirect detector performance may be optimized either by improving the structural parameters of the screen or by employing new phosphor materials with improved physical characteristics (e.g., x-ray absorption efficiency, intrinsic conversion efficiency, emitted light spectrum). Lu2O3:Eu is a relatively new phosphor material that exhibits improved scintillating properties indicating a promising material for mammographic applications. In this article, a custom validated Monte Carlo program was used in order to examine the performance of compact Lu2O3:Eu powdered phosphor screens under diagnostic mammography conditions (x-ray spectra: 28 kV Mo, 0.030 mm Mo and 32 kV W, 0.050 mm Rh). Lu2O3:Eu screens of coating weight in the range between 20 and 40 mg/cm2 were examined. The Monte Carlo code was based on a model using Mie-scattering theory for the description of light propagation within the phosphor. The overall performance of Lu2O3:Eu powdered phosphor screens was investigated in terms of the (i) quantum detection efficiency, (ii) luminescence efficiency, (iii) compatibility with optical sensors, (iv) modulation transfer function, (v) the Swank factor, and (vi) zero-frequency detective quantum efficiency. Results were compared to the traditional rare-earth Gd2O2S:Tb phosphor material. The increased packing density and therefore the light extinction properties of Lu2O3:Eu phosphor were found to improve the x-ray absorption (approximately up to 21% and 16% at 40 mg/cm2 for Mo and W x-ray spectra, respectively), the spatial resolution (approximately 2.6 and 2.4 cycles/mm at 40 mg/cm2 for Mo and W x-ray spectra, respectively), as well as the zero-frequency detective quantum efficiency (approximately up to 8% and 18% at 20 mg/cm2 for Mo and W x-ray spectra, respectively) of the screens in comparison to the Gd2O2S: Tb screens. Data obtained by the simulations indicate that certain optical properties of Lu2O3:Eu make this material a promising phosphor which, under appropriate conditions, could be considered for use in x-ray mammography imagers.
Asunto(s)
Europio/química , Aumento de la Imagen/instrumentación , Lutecio/química , Mamografía/instrumentación , Pantallas Intensificadoras de Rayos X , Diseño Asistido por Computadora , Diseño de Equipo , Análisis de Falla de Equipo , Europio/efectos de la radiación , Aumento de la Imagen/métodos , Lutecio/efectos de la radiación , Miniaturización , Método de Montecarlo , Polvos , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
Eu3+, Li+-codoped ZnO:Zn phosphor with intense Eu3+ emissions upon indirect excitation of near-UV light has been synthesized under reducing condition. Steady-state and time-resolved photoluminescence and diffuse reflectance spectra are measured to investigate properties of the luminescence. The results suggest that there exists prominent energy transfer from ZnO host to Eu3+ ions. A series of energy levels as temporary storage of excitation energy play a crucial role on this energy transfer process. Two kinds of Eu3+ sites in Eu3+, Li+-codoped ZnO:Zn are distinguished based on the emission and excitation spectra in comparison with pure Eu2O3.