RESUMO
Increasing awareness of the health and environment impacts of the antibiotics misuse or overuse, such as tetracycline (TC) in treatment or prevention of infections and diseases, has driven the development of robust methods for their detection in biological, environmental and food systems. In this work, we report the development of a new europium(III) complex functionalized silica nanoprobe (SiNPs-Eu3+) for highly sensitive and selective detection of TC residue in aqueous solution and food samples (milk and meat). The nanoprobe is developed by immobilization of Eu3+ ion onto the surface of silica nanoparticles (SiNPs) as the emitter and TC recognition unit. The ß-diketone configuration of TC can further coordinate with Eu3+ steadily on the surface of nanoprobe, facilitating the absorption of light excitation for Eu3+ emitter activation and luminescence "off-on" response. The dose-dependent luminescence enhancement of SiNPs-Eu3+ nanoprobe exhibits good linearities, allowing the quantitative detection of TC. The SiNPs-Eu3+ nanoprobe shows high sensitivity and selectivity for TC detection in buffer solution. Time resolved luminescence analysis enables the elimination of autofluorescence and light scattering for highly sensitive detection of TC in milk and pork mince with high accuracy and precision. The successful development of SiNPs-Eu3+ nanoprobe is anticipated to provide a rapid, economic, and robust approach for TC detection in real world samples.
Assuntos
Európio , Luminescência , Európio/análise , Európio/química , Dióxido de Silício , Tetraciclina/análise , Tetraciclina/química , AntibacterianosRESUMO
The syntheses and photophysical behavior of nine strongly luminescent nonadentate Eu(III) complexes are reported. Each complex is based on N-functionalized 1,4,7-triazacyclononane, and linkage to other groups or targeting vectors can occur either via amide bond formation to a coordinated pyridine p-aminopropyl group or via a nucleophilic substitution reaction involving thiol attack on a metal coordinated p-nitropyridyl moiety. Evidence is presented in favor of the latter conjugation strategy, as parallel work with maleimide conjugates was complicated or compromised by the propensity to undergo post-conjugation thiol exchange or succinimide ring hydrolysis reactions. Confocal microscopy and spectral imaging studies revealed that the peptide conjugate of AcCFFKDEL was found to localize selectively in the endoplasmic reticulum of mouse fibroblast cells, whereas the related maleimide conjugate was only observed in cellular lysosomes.
Assuntos
Complexos de Coordenação/análise , Retículo Endoplasmático/ultraestrutura , Európio/análise , Substâncias Luminescentes/análise , Peptídeos/análise , Animais , Fibroblastos/ultraestrutura , Maleimidas/análise , Camundongos , Microscopia Confocal , Células NIH 3T3 , Imagem Óptica , OrganelasRESUMO
In this work, the morphology, composition, crystal, and electronic structure of Ca8Mg(SiO4)4Cl2 (CMSOC) prepared by a high-temperature solid-state reaction technique are characterized first. To investigate the site occupancies of Eu3+ and Ce3+ in CMSOC, the emission spectra under well-chosen wavelength excitations and the corresponding excitation spectra by monitoring of the specific wavelength emissions are measured in detail for singly doped samples with different concentrations. Two kinds of Eu3+ or Ce3+ luminescence spectra are found. On the basis of the chemical environments of two Ca2+ sites and dielectric chemical bond theory, the sites of these two kinds of Eu3+ and Ce3+ luminescence spectra are respectively assigned. Because energy transfer between the two types of luminescent centers, concentration-dependent emission-wavelength shifting, and luminescence concentration quenching are negligible, the emission spectra of Eu3+ and Ce3+ give us a hint of their occupation preferences on two Ca2+ sites. The results indicate that, with an increase of the doping concentration, the Eu3+ ions with smaller cationic size show an occupation preference on the smaller Ca2+(1) sites, but the Ce3+ ions with larger cationic size are inclined to enter the larger Ca2+(2) sites. These opposite occupation preferences of Eu3+ and Ce3+ in CMSOC are thought to be the cationic-size-driven site selection.
Assuntos
Cério/análise , Európio/análise , Luminescência , Substâncias Luminescentes/química , Cálcio/química , Cloretos/química , Transferência de Energia , Íons/análise , Substâncias Luminescentes/síntese química , Medições Luminescentes , Magnésio/química , Tamanho da Partícula , Silicatos/química , Propriedades de SuperfícieRESUMO
BACKGROUND: Intrinsic iron in biological tissues frequently precludes unambiguous the identification of iron oxide nanoparticles when iron-based detection methods are used. Here we report the full methodology for synthesizing very small iron oxide nanoparticles (VSOP) doped with europium (Eu) in their iron oxide core (Eu-VSOP) and their unambiguous qualitative and quantitative detection by fluorescence. METHODS AND RESULTS: The resulting Eu-VSOP contained 0.7 to 2.7% Eu relative to iron, which was sufficient for fluorescent detection while not altering other important particle parameters such as size, surface charge, or relaxivity. A customized enhancer solution with high buffer capacity and nearly neutral pH was developed to provide an antenna system that allowed fluorescent detection of Eu-VSOP in cells and histologic tissue slices as well as in solutions even under acidic conditions as frequently obtained from dissolved organic material. This enhancer solution allowed detection of Eu-VSOP using a standard fluorescence spectrophotometer and a fluorescence microscope equipped with a custom filter set with an excitation wavelength (λex) of 338 nm and an emission wavelength (λem) of 616 nm. CONCLUSION: The fluorescent detection of Eu-doped very small iron oxide nanoparticles (Eu-VSOP) provides a straightforward tool to unambiguously characterize VSOP biodistribution and toxicology at tissue, and cellular levels, providing a sensitive analytical tool to detect Eu-doped IONP in dissolved organ tissue and biological fluids with fluorescence instruments.
Assuntos
Európio/análise , Compostos Férricos/análise , Nanopartículas/análise , Animais , Európio/farmacocinética , Compostos Férricos/síntese química , Compostos Férricos/farmacocinética , Camundongos , Camundongos Endogâmicos C57BL , Microscopia de Fluorescência/métodos , Nanopartículas/ultraestrutura , Nanotecnologia/métodos , Células RAW 264.7 , Distribuição TecidualRESUMO
Potassium fluoro-phosphate (KFP) glass singly doped with different concentrations of europium (Eu3+ ) or samarium (Sm3+ ) or co-doped (Sm3+ /Eu3+ ) was prepared, and their luminescence spectra were investigated. The phase composition of the product was verified by X-ray diffraction analysis. Optical transition properties of Eu3+ in the studied potassium phosphate glass were evaluated in the framework of the Judd-Ofelt theory. The radiative transition rates (AR ), fluorescence branching ratios (ß), stimulated emission cross-sections (σe ) and lifetimes (τexp ) for certain transitions or levels were evaluated. Red emission of Eu3+ was exhibited mainly by the 5 D0 â7 F2 transition located at 612 nm. Concentration quenching and energy transfer were observed from fluorescence spectra and decay curves, respectively. It was found that the lifetimes of the 5 D0 level increased with increase in concentration and then decreased. By co-doping with Sm3+ , energy transfer from Sm3+ to Eu3+ occurred and contributed to the enhancement in emission intensity. Intense orange-red light emission was obtained upon sensitizing with Sm3+ in KFP glass. This approach shows significant promise for use in reddish-orange lighting applications. The optimized properties of the Sm3+ /Eu3+ co-doped potassium phosphate glass might be promising for optical materials.
Assuntos
Európio/análise , Flúor/química , Fosfatos/química , Potássio/química , Samário/análise , Vidro/química , Espectroscopia de Ressonância Magnética , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
In spectral analysis, a chemical component is usually identified by its characteristic spectra, especially the peaks. If two components have overlapping spectral peaks, they are generally considered to be indiscriminate in current analytical chemistry textbooks and related literature. However, if the intensities of the overlapping major spectral peaks are additive, and have different rates of change with respect to variations in the concentration of the individual components, a simple method, named the 'common-origin ray', for the simultaneous determination of two components can be established. Several case studies highlighting its applications are presented.
Assuntos
Difusão Dinâmica da Luz/métodos , Processamento de Sinais Assistido por Computador , Espectrometria de Fluorescência/métodos , Espectrofotometria Ultravioleta/métodos , Cério/análise , Clorpromazina/análise , Európio/análise , Isomerismo , Modelos Teóricos , Naftóis/análise , Naftóis/química , Fenilalanina/análise , Fenilalanina/química , Prometazina/análise , Pontos Quânticos , Triptofano/análise , Triptofano/química , beta-Ciclodextrinas/químicaRESUMO
Contamination of soil with Americium (241Am) at nuclear sites in China poses a serious problem. We screened six plants, from five families, for their 241Am-enrichment potential. Europium (Eu), which is morphologically and chemically similar to the highly toxic 241Am, was used in its place. Moreover, the effects of sylvite, citric acid (CA), malic acid (MA), and humic acid (HA) on the absorption of 241Am by the plants, and its transport within them, were evaluated along with their effect on plant biomass and 241Am extraction volume. Barley and cabbage showed relatively stronger Eu accumulation capacities. Citric acid promoted the absorption of 241Am by barley roots and its transport within the plants. The effects of sylvite were not obvious and those of HA were the weakest in case of sunflower; HA, however, maximally increased the biomass of the plants. Our results could provide the basis for future radionuclide phytoremediation of contaminated soils.
Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Ácido Cítrico/farmacologia , Európio/análise , Malatos/farmacologia , Plantas/química , Cloreto de Potássio/farmacologia , Biomassa , China , Substâncias Húmicas , Plantas/efeitos dos fármacos , Poluentes do Solo/análiseRESUMO
Luminescent lanthanide ion complexes have received increasing attention because of their unique optical properties. Herein, we discovered that the luminescence of europium(III) (Eu(3+)) could be regulated by Ag(+) and SCN(-) in seconds with enoxacin (ENX) as the antenna. Under given conditions, only the simultaneous introduction of Ag(+) and SCN(-) could remarkably enhance the luminescence intensity of Eu(3+)-ENX complexes. This phenomenon has been exploited to design an "AND" logic gate and specific luminescence turn-on assays for sensitively sensing Ag(+) and SCN(-) for the first time. Furthermore, the addition of S(2-) resulted in efficient luminescence quenching of the Eu(3+)/ENX/Ag(+)/SCN(-) system due to the strong affinity between Ag(+) and S(2-). Thus, a new luminescent sensing platform for S(2-) was established, which exhibited excellent selectivity and high sensitivity. S(2-) could be detected within the concentration range of 100 nM to 12.5 µM with a detection limit of 60 nM. Such sensing system features simplicity, rapidity, and flexibility. Moreover, this proposed Eu(3+)-based luminescent assay could be successfully applied in the real environmental water sample analysis.
Assuntos
Enoxacino/química , Európio/análise , Luminescência , Sulfetos/análise , Poluentes Químicos da Água/análise , Computadores Moleculares , Íons/análise , Lagos , Lógica , Medições Luminescentes , Prata/química , Tiocianatos/químicaRESUMO
Europium speciation is investigated by time-resolved luminescence spectroscopy (TRLS) in the presence of Suwannee River fulvic acid (SRFA). From complexation isotherms built at different total Eu(III) concentrations, pH values, ionic strength, and SRFA concentrations, it appears that two luminescence behaviors of Eu(III) are occurring. The first part, at the lowest CSRFA values, is showing the typical luminescence evolution of Eu(III) complexed by humic substances--that is, the increase of the asymmetry ratio between the (5)D0 â (7)F2 and (5)D0 â (7)F1 transitions up to a plateau--, and the occurrence of a biexponential decay--the first decay being faster than free Eu(3+). At higher CSRFA, a second luminescence mode is detected as the asymmetry ratio is increasing again after the previous plateau, and could correspond to the formation of another type of complex, and/or it can reflect a different spatial organization of complexed europium within the SRFA structure. The luminescence decay keeps on evolving but link to hydration number is not straightforward due to quenching mechanisms. The Eu(III) chemical environment evolution with CSRFA is also ionic strength dependent. These observations suggest that in addition to short-range interactions--intraparticulate complexation--, there might be interactions at longer range--interparticulate repulsion--between particles that are complexing Eu(III) at high CSRFA. These interactions are not yet accounted by the different complexation models.
Assuntos
Benzopiranos/química , Európio/química , Análise Espectral/métodos , Európio/análise , Substâncias Húmicas , Concentração de Íons de Hidrogênio , Luminescência , Concentração OsmolarRESUMO
The adsorption mechanism of U(VI) and Eu(III) on carbonaceous nanofibers (CNFs) was investigated using batch, IR, XPS, XANES, and EXAFS techniques. The pH-dependent adsorption indicated that the adsorption of U(VI) on the CNFs was significantly higher than the adsorption of Eu(III) at pH < 7.0. The maximum adsorption capacity of the CNFs calculated from the Langmuir model at pH 4.5 and 298 K for U(VI) and Eu(III) were 125 and 91 mg/g, respectively. The CNFs displayed good recyclability and recoverability by regeneration experiments. Based on XPS and XANES analyses, the enrichment of U(VI) and Eu(III) was attributed to the abundant adsorption sites (e.g., -OH and -COOH groups) of the CNFs. IR analysis further demonstrated that -COOH groups were more responsible for U(VI) adsorption. In addition, the remarkable reducing agents of the R-CH2OH groups were responsible for the highly efficient adsorption of U(VI) on the CNFs. The adsorption mechanism of U(VI) on the CNFs at pH 4.5 was shifted from inner- to outer-sphere surface complexation with increasing initial concentration, whereas the surface (co)precipitate (i.e., schoepite) was observed at pH 7.0 by EXAFS spectra. The findings presented herein play an important role in the removal of radionuclides on inexpensive and available carbon-based nanoparticles in environmental cleanup applications.
Assuntos
Európio/análise , Nanofibras/química , Nanofibras/ultraestrutura , Nitrato de Uranil/análise , Poluentes Radioativos da Água/análise , Adsorção , Európio/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Propriedades de Superfície , Nitrato de Uranil/química , Poluentes Radioativos da Água/química , Espectroscopia por Absorção de Raios XRESUMO
Terbium and rare earths recovery from fluorescent powders of exhausted lamps by acid leaching with hydrochloric acid was the objective of this study. In order to investigate the factors affecting leaching a series of experiments was performed in according to a full factorial plan with four variables and two levels (42). The factors studied were temperature, concentration of acid, pulp density and leaching time. Experimental conditions of terbium dissolution were optimized by statistical analysis. The results showed that temperature and pulp density were significant with a positive and negative effect, respectively. The empirical mathematical model deducted by experimental data demonstrated that terbium content was completely dissolved under the following conditions: 90 °C, 2 M hydrochloric acid and 5% of pulp density; while when the pulp density was 15% an extraction of 83% could be obtained at 90 °C and 5 M hydrochloric acid. Finally a flow sheet for the recovery of rare earth elements was proposed. The process was tested and simulated by commercial software for the chemical processes. The mass balance of the process was calculated: from 1 ton of initial powder it was possible to obtain around 160 kg of a concentrate of rare earths having a purity of 99%. The main rare earths elements in the final product was yttrium oxide (86.43%) following by cerium oxide (4.11%), lanthanum oxide (3.18%), europium oxide (3.08%) and terbium oxide (2.20%). The estimated total recovery of the rare earths elements was around 70% for yttrium and europium and 80% for the other rare earths.
Assuntos
Utensílios Domésticos , Ácido Clorídrico/química , Iluminação , Reciclagem/métodos , Térbio/química , Cério/análise , Cério/química , Európio/análise , Európio/química , Lantânio/análise , Lantânio/química , Óxidos/análise , Óxidos/química , Projetos de Pesquisa , Térbio/análise , Ítrio/análise , Ítrio/químicaRESUMO
Despite long-standing efforts, there is no agreed upon structural model for electrolyte solutions at air-liquid interfaces. We report the simultaneous detection of the near-surface and bulk coordination environments of a trivalent metal cation (europium) in an aqueous solution by use of X-ray absorption spectroscopy. Within the first few nanometers of the liquid surface, the cations exhibit oxygen coordination typical of inner-sphere hydration of an aquated Eu(3+) cation. Beyond that, outer-sphere ion-ion correlations are observed that are otherwise not present in the bulk electrolyte. The combination of near-surface and bulk sensitivities to probe metal ion speciation in electrolyte solutions is achieved by detecting electron-yield and X-ray fluorescence signals from an inverted pendant drop. The results provide new knowledge about the near-surface chemistry of aqueous solutions of relevance to aerosols and ion transport processes in chemical separations and biological systems.
Assuntos
Európio/análise , Európio/química , Cátions/análise , Cátions/química , Soluções , Propriedades de Superfície , Espectroscopia por Absorção de Raios X/instrumentaçãoRESUMO
A series of single-phase full-color emitting Li2 Sr1-x-y SiO4 :xDy(3+) ,yEu(3+) phosphors were synthesized by solid-state reaction and characterized by X-ray diffraction and photoluminescence analyses. The samples showed emission peaks at 488 nm (blue), 572 nm (yellow), 592 nm (orange) and 617 nm (red) under 393 nm excitation. The photoluminescence excitation spectra, comprising the Eu-O charge transfer band and 4f-4f transition bands of Dy(3+) and Eu(3+) , range from 200 to 500 nm. The Commission Internationale de I'Eclairage chromaticity coordinates for Li2 Sr0.98-x SiO4 :0.02Dy(3+) ,xEu(3+) phosphors were simulated. By manipulating Eu(3+) and Dy(3+) concentrations, the color points of Li2 Sr1-x-y SiO4 :xDy(3+) ,yEu(3+) were tuned from the greenish-white region to white light and eventually to reddish-white region, demonstrating that a tunable white light can be obtained by Li2 Sr1-x-y SiO4 :xDy(3+) ,yEu(3+) phosphors. Li2 Sr0.98-x SiO4 :0.02Dy(3+) , xEu(3+) can serve as a white-light-emitting phosphor for phosphor-converted light-emitting diode.
Assuntos
Disprósio/análise , Európio/análise , Luz , Silicatos/química , LuminescênciaRESUMO
The first example of cell imaging using two independent emission components from a dinuclear d/f complex is reported. A water-stable, cell-permeable Ir(III) /Eu(III) dyad undergoes partial IrâEu energy transfer following two-photon excitation of the Ir unit at 780â nm. Excitation in the near-IR region generated simultaneously green Ir-based emission and red Eu-based emission from the same probe. The orders-of-magnitude difference in their timescales (Ir ca. µs; Eu ca. 0.5â ms) allowed them to be identified by time-gated detection. Phosphorescence lifetime imaging microscopy (PLIM) allowed the lifetime of the Ir-based emission to be measured in different parts of the cell. At the same time, the cells are simultaneously imaged by using the Eu-based emission component at longer timescales. This new approach to cellular imaging by using dual d/f emitters should therefore enable autofluorescence-free sensing of two different analytes, independently, simultaneously and in the same regions of a cell.
Assuntos
Európio/análise , Irídio/análise , Substâncias Luminescentes/análise , Imagem Óptica , Linhagem Celular , Transferência de Energia , Fibroblastos/citologia , Humanos , Luminescência , Microscopia/métodos , Imagem Óptica/métodos , Fótons , Solubilidade , Água/químicaRESUMO
A new sensitive quaternary photoluminescence enhancement system has been successfully developed to determine trace amounts of Eu(3+) and Zn(2+). The photoluminescence intensity of Eu - N-(o-vanilin)-1,8-diaminonaphthalene systems was greatly increased by the addition of specific concentrations of 1, 10-phenanthroline and Zn(2+). The excitation and emission wavelengths were 274 and 617 nm, respectively. Under optimal system conditions, the photoluminescence intensity showed a linear response toward Eu(3+) in the range of 5.0 × 10(-6) ~ 2.0 × 10(-5) M with a limit of detection (= 2.2 × 10(-9) M) and the photoluminescence intensity of the system decreased linearly by increasing the Zn(2+) concentration in the range of 5.0 × 10(-8) ~ 1.0 × 10(-6) M with a limit of detection (= 8.8 × 10(-11) M). This system was successfully applied for the determination of trace amounts of Eu(3+) in a high purity La2O3 matrix and in the synthetic rare earth oxide mixture, and of Zn(2+) in a high purity Mg(NO3)2 · 6H2O matrix and in synthetic coexisting ionic matrixes. The energy transfer mechanism, photoluminescence enhancement of the system and interference of other lanthanide ions and common coexisting ions were also studied in detail.
Assuntos
Európio/análise , Substâncias Luminescentes/química , Medições Luminescentes/métodos , Zinco/análise , 2-Naftilamina/análogos & derivados , 2-Naftilamina/química , Benzaldeídos/química , Substâncias Luminescentes/síntese química , Fenantrolinas/químicaRESUMO
Luminescent europium complexes are used in a broad range of applications as a result of their particular emissive properties. The synthesis and application of bright, highly water-soluble, and negatively charged sulfonic- or carboxylic acid derivatives of para-substituted aryl-alkynyl triazacyclononane complexes are described. Introduction of the charged solubilizing moieties suppresses cellular uptake or adsorption to living cells making them applicable for labeling and performing assays on membrane receptors. These europium complexes are applied to monitor fluorescent ligand binding on cell-surface proteins with time-resolved Förster resonance energy transfer (TR-FRET) assays in plate-based format and using TR-FRET microscopy.
Assuntos
Compostos Aza/análise , Complexos de Coordenação/análise , Európio/análise , Transferência Ressonante de Energia de Fluorescência/métodos , Substâncias Luminescentes/análise , Microscopia/métodos , Piperidinas/análise , Receptores Acoplados a Proteínas G/metabolismo , Compostos Aza/metabolismo , Complexos de Coordenação/metabolismo , Európio/metabolismo , Células HEK293 , Humanos , Ligantes , Substâncias Luminescentes/metabolismo , Piperidinas/metabolismo , Ligação Proteica , Receptores Acoplados a Proteínas G/análise , Solubilidade , Água/químicaRESUMO
The integration of the ORION digital signal processing-based MCA system coupled with a 3â³ × 3â³ NaI(Tl) detector assembly with a GM detector for counting beta (ß) has eliminated the need for a standalone ß-γ method in which U3O8 is determined by gross ß and gross γ counting. Uraniferous and mixed U-Th samples were taken up for study and compared with the results obtained from Canberra p-type coaxial high resolution gamma ray spectrometry detector. In uraniferous samples, U3O8 values obtained are within ±10%, whereas in the case of mixed U-Th samples, U3O8 values are within ±15%. Regression graphs drawn between the outcomes from the two analytical systems indicate R2 > 0.95 for Ra(eU3O8) and ThO2. In uraniferous samples, the R2 value for U3O8 was found to be > 0.99, but in mixed U-Th samples, it is 0.92. The closeness of agreement between the results obtained from two methods at various concentrations over the analytical range shows that the integrated system is suitable for the quantitative determination of eU3O8, U3O8, Ra(eU3O8), ThO2 and K in geological rock samples.
Assuntos
Monitoramento de Radiação , Espectrometria gama , Monitoramento de Radiação/métodos , Monitoramento de Radiação/instrumentação , Espectrometria gama/métodos , Espectrometria gama/instrumentação , Partículas beta , Urânio/análise , Európio/química , Európio/análise , Dosimetria Termoluminescente/instrumentação , Dosimetria Termoluminescente/métodos , Processamento de Sinais Assistido por Computador , Tálio/análise , Tório/análise , Iodeto de SódioRESUMO
The development and characterization of novel, molecularly imprinted polymer nanofilament-based optical sensors for the analysis of enrofloxacin, an antibiotic widely used for human and veterinary applications, is reported. The polymers were prepared by nanomolding in porous alumina by using enrofloxacin as the template. The antibiotic was covalently immobilized on to the pore walls of the alumina by using different spacers, and the prepolymerization mixture was cast in the pores and the polymer synthesized anchored onto a glass support through UV polymerization. Various parameters affecting polymer selectivity were evaluated to achieve optimal recognition, namely, the spacer arm length and the binding solvent. The results of morphological characterization, binding kinetics, and selectivity of the optimized polymer material for ENR and its derivatives are reported. For sensing purposes, the nanofilaments were incubated in solutions of the target molecule in acetonitrile/HEPES buffer (100â mM, pHâ 7.5, 50:50, v/v) for 20â min followed by incubation in a 10â mM solution of europium(III) ions to generate a europium(III)-enrofloxacin complex on the polymer surface. The detection event was based on the luminescence of the rare-earth ion (λexc=340â nm; λem=612â nm) that results from energy transfer from the antibiotic excited state to the metal-ion emitting excited state. The limit of detection of the enrofloxacin antibiotic was found to be 0.58â µM.
Assuntos
Antibacterianos/química , Európio/química , Fluoroquinolonas/química , Antibacterianos/análise , Enrofloxacina , Európio/análise , Fluoroquinolonas/análise , Luminescência , Estrutura Molecular , Nanoestruturas , Polímeros/químicaRESUMO
A series of five europium(III) complexes has been prepared from heptadentate N5O2 ligands that possess a brightness of more than 10 mM(-1) cm(-1) in water, following excitation over the range λ=330-355 nm. Binding of several oxy anions has been assessed by emission spectral titrimetric analysis, with the binding of simple carboxylates, lactate and citrate involving a common ligation mode following displacement of the coordinated water. Selectivity for bicarbonate allows the rapid determination of this anion in human serum, with K(d)=37 mM (295 K). The complexes are internalised quickly into mammalian cells and exhibit a mitochondrial localisation at early time points, migrating after a few hours to reveal a predominant lysosomal distribution. Herein, we report the synthesis and complexation behaviour of strongly emissive europium (III) complexes that bind oxy-anions in aqueous media with an affinity and selectivity profile that is distinctively different from previously studied systems.
Assuntos
Ânions/química , Compostos Aza/química , Bicarbonatos/análise , Bicarbonatos/química , Ácido Cítrico/química , Európio/análise , Európio/química , Piperidinas/química , Soro/química , Humanos , Ligantes , Luminescência , Soro/metabolismoRESUMO
A stable liposome-based time-resolved luminescence resonance energy transfer (TR-LRET) assay was developed based on the interaction of biotinylated lipids and streptavidin. Eu(3+) ion chelated to 4,4,4-trifluoro-1-(2-naphthalenyl)-1,3-butanedione and trioctylphosphine oxide was incorporated into liposomes. Acceptor-labeled streptavidin bound to biotinylated lipids of the liposomes enables TR-LRET. A stable assay performance was achieved by optimization. High Eu(3+) signal and stability, low variation, and sensitivity below 100 pM for free biotin was achieved by incorporating the chelate into liposomes containing cholesterol in a carbonate buffer. Potentially, the stable assay compared with the assay without cholesterol offers an improved platform to liposome-based detection systems.