Fluorescence Intensity Of Tb3 Research Articles

Preparation and luminescence properties of Tb3+-Sm3+ co-doped K3Gd(PO4)2 crystalline glass ceramics

In this paper, Tb3+-Sm3+ co-doped glass ceramics with K3Gd(PO4)2 crystal phase were successfully prepared by methods of melting curing crystallization. The optimal heat treatment conditions for the samples were determined to be held for 1.5 h at 750 °C by combining differential scanning calorimeter (DSC), x-ray diffraction (XRD) and scanning electron microscope (SEM). Under this condition, glass ceramics still have a high transmittance in the range of 400∼700 nm, up to 80 %. It was calculated that the optical band gap value of glass ceramic is smaller than that of glass, indicating that the sample structure was changed by heat treatment. Fluorescence lifetime and Dexter's theory demonstrate that Tb3+ transfers energy to Sm3+. By fixing the concentration of Tb3+ and changing the doping concentration of Sm3+, the luminous color of glass ceramics can be adjusted. At 458 K, the fluorescence intensity of Tb3+ and Sm3+ decreased to 89 % and 85 % of that at 298 K. Study shows that the prepared glass ceramics have potential applications in white light emitting diodes (WLEDs).

One‐pot synthesis of copper nanocluster/Tb‐MOF composites for the ratiometric fluorescence detection of Cu2+

The increasing degradation of ecosystems due to heavy metal residues has led to environment and food contamination, prompting the development of convenient platforms for monitoring heavy metals. Here, a new dual-emission fluorescent sensor CuNCs@Tb@UiO-66-(COOH)2 for the detection of copper ions (Cu2+ ) has been synthesized using one-pot encapsulation of Tb(III) and glutathione-stabilized copper nanoclusters (CuNCs) into metal-organic frameworks (MOFs) UiO-66-(COOH)2 . In this ratiometric sensor, the fluorescence intensity of Tb3+ decreased significantly upon the addition of Cu2+ , whereas that of CuNCs showed good stability, together with an apparent colour change. Therefore, ratiometric fluorescence detection of Cu2+ can be accomplished by measuring the ratio of the fluorescence intensity at the 450 nm (F450 ) wavelength of CuNCs to the 548 nm (F548 ) emission of Tb3+ in the fluorescence spectra of the CuNCs@Tb@UiO-66-(COOH)2 suspension. Moreover, the obtained fluorescent probe showed good results in the detection of actual samples. This work can provide the basis of method for the exploration of ratiometric fluorescence and visual sensors of trace pollutants analysis in complicated samples.

Highly sensitive detection of dopamine based on gold nanoflowers enhanced-Tb(III) fluorescence

We developed a trace level detection method for dopamine (DA) based on the metal-enhanced fluorescence (MEF) effect of gold nanoflowers (AuNFs). AuNFs prepared were excellent enhancement fluorescence substrates due to their unique morphology with rich edges and sharp quoins. DA was the target analyte and also as a bridge reagent that could regulate the distance between AuNFs and Tb3+. The characteristic fluorescence of Tb3+ was enhanced significantly through the synergistic effect between the luminescence sensitized by DA and the MEF caused by AuNFs. Under the optimum experimental conditions, the fluorescence intensity of Tb3+ at 545 nm demonstrated very significant sensing ability against DA concentration and showed a good linear relationship in the range of 0.80–300 nM and the limit of detection was 0.21 nM (S/N = 3). The proposed method was also validated in serum samples and the dopamine hydrochloride injection samples with satisfactory results.

Development of terbium-sensitized fluorescence method for the determination of alendronate in biological samples followed by magnetic solid-phase extraction

A new method based on combining terbium-sensitized fluorescence method and magnetic solid-phase extraction (MSPE) was developed for the quantification of alendronate (ALD) in biological samples. The fluorescence intensity of Tb3+-ALD complex was measured at 545 nm following elution from polymer coated magnetic nanoparticles surface. MNPs modified with PEG-b-P(IA-co-DMAEMA) block copolymer were synthesized and the effects of various parameters on MSPE efficiency and the fluorescence intensity were investigated. The dynamic assay range for ALD determination was obtained (0.04 to 0.8 mg/L) with a quantification limit of 0.033 mg/L. The accuracy of recovery, reproducibility, and sensitivity of the developed method suggested that it can be feasibly developed to a platform for monitoring the ALD concentration in human urine and plasma samples.

Luminescence determination of microRNAs based on the use of terbium(III) sensitized with an enzyme-activated guanine-rich nucleotide.

A method is reported for the fluorometric quantitation of microRNA. It is making use of a luminescent probe deribed from terbium(III) ion whose fluorescence is sensitized with a guanine-rich (G-rich) nucleotide. The probe has a large Stokes' shift and strong and sharp emission bands. The assay relies on the wide substrate specificity of terminal deoxynucleotidyl transferase (TdTase), which catalyzes the formation of long G-rich nucleotides when using microRNA primer as a trigger to start the polymerization. The addition of Tb(III) induces the formation of a G-quadruplex from the G-rich nucleotide, and this strongly enhances the green fluorescence of Tb(III) (peaking at 545nm upon photoexcitation at 290nm). Specifically, microRNA-21 was chosen as the analyte. The fluorescence intensity of Tb(III) increases linearly in the 1 pM to 1nM microRNA concentration range, and the detection limit is as low as 0.11 pM. The method can distinguish between family members of microRNA and performs excellently even when applied to extracts of cancer cells. Graphical abstract A fluorometric technique is reported for the determination of microRNA. It is based on signal enhancement based on the sensitization of terbium(III) via a guanine-rich nucleotide sequence. Klenow Fragment exo- (KFexo-) generates DNA sequence at the 3'-OH of microRNA, and terminal deoxynucleotidyl transferase (TdTase) catalyzes the formation of long G-rich nucleotides.

Fluorimetric determination of febuxostat in dosage forms and in real human plasma via Förster resonance energy transfer

A rapid, simple, selective and precise fluorimetric method was developed and validated for determination of a selective xanthine oxidase inhibitor; febuxostat (FBX) in pharmaceutical formulations and in human plasma. The proposed method is based on quenching effect of FBX on the fluorescence intensity of terbium (Tb3+ ) through fluorescence resonance energy transfer (FRET) from Tb3+ to FBX. The formed complex was measured at λex. 320nm/λem. 490nm against a reagent blank. Fluorescence intensity of Tb3+ was diminished when FBX was added. A linear relationship between the fluorescence quenching value of the formed complex ΔF=FTb3+-FFBX-Tb3+ and the concentration of FBX was investigated. The reaction conditions and the fluorescence spectral properties of the complex have been studied. The linearity range of the developed method was 1.0-16.0μg/ml. The suggested method was applied successfully for the estimation of FBX in bulk powder, dosage forms and spiked plasma samples with excellent recoveries (96.79-98.89%). In addition, the developed method has been successfully applied for determination of FBX in real plasma samples collected from healthy volunteers with good recoveries (82.06-85.65%). All obtained results of the developed method were statistically analyzed and validated according to ICH (International Conference on Harmonization) guidelines.

Analytical studies of the interaction of Tb(III)-2-{[(4-methoxy benzoyl) oxy]} methyl benzoic acid binary complex with nucleosides

The interaction of Tb(III)-2-{[(4-methoxy benzoyl) oxy]} methyl benzoic acid binary complex with nucleosides (adenosine, cytidine, guanosine and inosine) was investigated using UV and fluorescence methods. The reaction of Tb-complex with cytidine, guanosine and adenosine is accompanied by shift to longer wavelength in the absorption band, while there is a blue shift in the absorption band with an enhancement in the molar absorptivity upon the reaction with inosine. The fluorescence intensity of Tb(III)-2-{[(4- methoxy benzoyl) oxy]} methyl benzoic acid binary complex at λ = 545 nm (5D4 → 7F5) was decreased with the addition of the nucleoside molecule following the order: cytidine > inosine > guanosine > adenosine.

Flexible composite nanobelts: facile electrospinning construction, structure and color-tunable photoluminescence

The flexible color-tunable [Eu(BA)3phen + Tb(BA)3phen]/PMMA composite nanobelts have been fabricated by single axial electrospinning. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and fluorescence spectroscopy were used to characterize the final products. As-prepared nanobelts are almost uniform and the thickness and width of them are respectively ca. 890 nm and 16.6 ± 0.09 μm. The fluorescence intensity of Eu3+ is increased with adding more Eu(BA)3phen into the composite nanobelts, and the fluorescence intensity of Tb3+ is found to increase monotonically with introducing more Tb(BA)3phen into the composite nanobelts. By adjusting the ratio of Eu(BA)3phen to Tb(BA)3phen complexes, the fluorescence color of composite nanobelts can be tuned from red to yellow, yellow green, and green under the excitation of 290-nm single-wavelength ultraviolet light. Besides, the emission color could also be tuned easily from red to yellow, yellow to green via variation of excitation wavelengths. The novel color-tunable composite nanobelts have potential applications in the fields of color displays and sensor systems.

Spectrofluorimetric Determination of Bilirubin Using Enoxacine-Terbium Probe

A new spectrofluorimetric method was developed for determination of trace amount of bilirubin. Using enoxacine–terbium ion as a fluorescent probe, in the buffer solution of pH=5.8, BR can remarkably reduce the fluorescence intensity of the ENX-Tb3+ complex at λ=545nm and the reduced fluorescence intensity of Tb3+ ion is in proportion to the concentration of BR. Optimum conditions for the determination of BR were also investigated. The linear range and detection limit for the determination of BR are 1.0×10-7～4.5×10-6mol/L and 8.1×10-8mol/L. This method is simple, practical and can be successfully applied to assess BR in serum samples.

PHOTONIC BAND GAP EFFECT ON ENERGY TRANSFER IN Tb3+, Eu3+ CO-DOPED TiO2 INVERSE OPAL FILMS

The energy transfer from Tb 3+ to Eu 3+ co-doped TiO 2( TiO 2: Tb , Eu ) inverse opal photonic crystals was investigated by photoluminescence. The results showed that the photonic band gap enhanced energy transfer from the donor Tb 3+ to the acceptor Eu 3+. When the fluorescence emission wavelength of Tb 3+ overlaps with the photonic band gap, the fluorescence intensity of Tb 3+ is suppressed, while the fluorescence intensity of Eu 3+ is enhanced. Energy transfer efficiencies were attributed to the tuning effects of energy transfer in the photoluminescence process by photonic crystal structure.

Research on the Effect of Doping Ca Ion and Organic Solvent on the Luminescent Intensity of Tb Complex Material

A Tb (III) ternary complex luminescent material has been synthesized and characterized by infrared spectrum. The luminescent properties of Tb (III) luminescent material were studied in solid and in ethanol, methanol and DMSO solutions. The effect of solvent factors and the doping different concentration of Ca (II) ion on the fluorescence intensity of Tb (III) complex luminescent material were tested. The results show that both the solvents and the doping different concentration of Ca (II) ion could quench the luminescent intensity of Tb (III) complex luminescent material.

Energy Transfer Enhancement in Eu3+, Tb3+‐Doped SiO2 Inverse Opal Photonic Crystals

The energy transfer from Tb3+ to Eu3+‐doped SiO2 (SiO2:Eu3+, Tb3+) inverse opal photonic crystals was investigated by photoluminescence and fluorescence lifetime. The results showed that the photonic band gap enhanced energy transfer from the donor Tb3+ to the acceptor Eu3+. When the fluorescence emission wavelength of Tb3+ overlaps the photonic band gap, the fluorescence intensity of Tb3+ is suppressed, and the fluorescence intensity of Eu3+ is increased because of the enhancement of energy transfer. In addition, the fluorescence lifetime of Tb3+ decreased.

Spectrofluorimetric determination of folic acid in tablets and urine samples using 1,10‐phenanthroline‐terbium probe

A new spectrofluorimetric method was reported for the determination of folic acid (FA), based on its quenching effect on the fluorescence intensity of Tb(3+) -1,10-phenanthroline complex as a fluorescent probe. The quenched fluorescence intensity at an emission wavelength of 545 nm was proportional to the concentration of FA in Tris-HCl buffer solution of pH 6.2. The effects of pH, time, order of addition of reagents, temperature and concentrations of Tb(3+) , buffer and 1,10-phenanthroline were investigated and optimized. The linear range for the determination of FA was 0.01-1.1 mg/L. The detection limit was 0.003 mg/L and the relative standard deviation for replicated determination of 1 mg/L of folic acid was 1.2%. This method was simple, practical and relatively free from interference effects. It was successfully applied to assess FA in pharmaceutical tablets and urine samples.

氮杂菲稀土配合物的合成、表征及其荧光性能

Eleven rare earth complexes were synthesized with dibenzoylmethane(HDBM),1-phenyl-3-biphenyl-1,3-dione(HPBPD) as the first ligands and 1,10-phenanthroline(phen),dipyrido [3,2-a:2′,3′-c] quinoxaline(dpq),dipyrido-[3,2-a:2′,3′-c]phenazine(dppz) as the second ligands.Their elemental analysis,TG-DTA,UV spectra,IR spectra and fluorescence spectra were measured,the results indicate that the complexes have the compositions of RE(DBM)3L and RE(PBPD)3L·1/2H2O(RE3+= Eu3+,Tb3+;L=phen,dpq,dppz).The molar conductivity shows that all the complexes are non-electrolyte.The data of IR spectra and UV spectra indicate that the azatriphenylenes through the N atoms of the phenanthroline moiety and HDBM,HPBPD through oxygen atoms coordinated with RE3+ ions,respectively.The fluorescence spectra data show that the fluorescence intensity of β-diketone Eu3+ complexes are stronger than the series of complexes of terbium.The abilities of energy transmission of phen and dpq are stronger than dppz.The luminance properties of the rare earth complexes were studied in detail.The triplet state energy of HDBM(20 700 cm-1) is higher than that of Eu3+ 5D0(17 293 cm-1) and the energy of Tb3+ 5D4(20 454 cm-1).In all the ternary complexes,Eu(Ⅲ) complexes have strong fluorescence,while the fluorescence intensity of Tb(Ⅲ) complexes is less than that of Eu(Ⅲ) complexes,which is due to the small difference between the triplet energy of HDBM and the lowest excited state energy of Tb3+.Thus it is possible that energy transfer from HDBM ligand to Eu3+ is more effective.As a high UV absorption coefficient for organic ligands,the energy transfer is effectively to the rare earth luminescent center ion,producing a characteristic emission spectrum.

Determination of methotrexate in biological fluids and a parenteral injection using terbium-sensitized method.

A new sensitive, simple and rapid method for determination of methotrexate (MTX) was developed based on quenching effects of MTX on the fluorescence intensity of Tb(3+)-1,10-phenanthroline complex. The fluorescence intensity was measured with excitation wavelength of 300 nm and emission wavelength of 545 nm and the quenched fluorescence intensity is proportional to the concentration of MTX in Tris-HCl buffer solution with a pH of 7.0. The effects of pH, time, order of addition of the reagents, temperature and the concentrations of Tb(3+), buffer and 1,10-phenanthroline were investigated and optimized. The obtained linear range for the determination of MTX was 0.02-10 μg/mL. The detection limits (signal: noise = 3) was 0.015 μg/mL and the relative standard deviation for replicated determinations of 1 μg/mL of MTX was 1.9%. The proposed method is a simple, practical and relatively free from interference effects and was successfully applied to assess MTX in urine, serum and samples of an injection solution.

Spectrofluorimetric determination of buparvaquone in biological fluids, food samples and a pharmaceutical formulation by using terbium–deferasirox probe

A simple spectrofluorimetric method is described for the determination of buparvaquone (BPQ), based on its quenching effect on the fluorescence intensity of Tb3+–deferasirox (DFX) complex as a fluorescent probe. The excitation and emission wavelengths were 328 and 545nm, respectively. The optimum conditions for determination of BPQ were investigated considering the effects of various affecting parameters. The variations in fluorescence intensity of the system showed a good linear relationship with the concentration of BPQ in the range of 10–1500μgL−1, its correlation coefficient was 0.999 with the detection and quantification limits of 1.1 and 3.4μgL−1, respectively. Linearity, reproducibility, recovery, limits of detection and quantification made the method suitable for BPQ assay in biological fluids, meat, dairy products and BPQ parenteral solutions (vials). The method was applied to real samples of serum and milk of three cows receiving BPQ.

Investigations into the synthesis and fluorescence properties of Tb(III) complexes of a novel bis-β-diketone-type ligand and a novel bispyrazole ligand

A novel bis-β-diketone organic ligand, 1,1′-(2,6-bispyridyl)bis-3-( p-methoxyphenyl)-1,3-propanedione (L 1) and its derivatives, a novel bispyrazole ligand, 2,6-bis(5-(4-methoxyphenyl)-1H-pyrazol-3-yl)pyridine (L 2) were designed and synthesized and their complexes with Tb(III) ion were successfully prepared. The ligands and the corresponding metal complexes were characterized by elemental analysis, infrared, proton nuclear magnetic resonance spectroscopy and TG-DTA. Analysis of the IR spectra suggested that the lanthanide metal ion Tb(III) coordinated to the ligands via the nitrogen atom of the pyridine ring and the carbonyl oxygen atoms for ligand L 1 and the nitrogen atom of the pyrazole ring for ligand L 2. The fluorescence properties of the two complexes in solid state were investigated and it was discovered that the Tb(III) ions could be sensitized by both the ligand (L 1) and ligand (L 2) to some extent. In particular, the complex of ligand (L 2) is a better green luminescent material that could be used as a candidate material in organic light-emitting devices (OLEDs) since it could be much better sensitized by the ligand (L 2), and the fluorescence intensity of Tb(III) complex of L 2 are almost as twice strong as L 1's.

Sensitive determination of enoxacin by its enhancement effect on the fluorescence of terbium(III)–sodium dodecylbenzene sulfonate and its luminescence mechanism

The fluorescence system of enoxacin–Tb 3+–sodium dodecylbenzene sulfonate (SDBS) was investigated in this paper. The experiments indicated that the fluorescence intensity of Tb 3+–SDBS was greatly enhanced by enoxacin. Accordingly, a sensitive fluorimetric method for determining enoxacin was established. The fluorescence intensity was measured by a 1-cm quartz cell with an excitation wavelength of 290 nm and an emission wavelength of 545 nm. The enhanced fluorescence intensity of the system (Δ F) showed a good linear relationship with the concentration of enoxacin in the range of 5.0×10 −9 to 2.0×10 −6 mol L −1, its correlation coefficient was 0.9992 and the detection limit (S/N=3) was 2.8×10 −9 mol L −1. The presented method was used to determine enoxacin in real pharmaceutical samples. The luminescence mechanism was also discussed in detail. In the fluorescence system of enoxacin–Tb 3+–SDBS, SDBS not only acted as the surfactant but also acted as the energy donor.

Determination of albumins by its quenching effect on the fluorescence of Tb 3+-oxolinic acid complex in presence of sodium dodecyl sulphate

It is found that the fluorescence intensity of Tb 3+-oxolinic acid (OA) complex can be greatly quenched by albumins in sodium dodecyl sulphate (SLS). Under optimum conditions, the quenched fluorescence intensity is in proportion to the concentration of proteins in the range of 5.0×10 −8–1.0×10 −5 g ml −1 for bovine serum albumin (BSA), 1.0×10 −7–1.0×10 −5 g ml −1 for human serum albumin (HSA) and 4.0×10 −7–1.0×10 −5 g ml −1 for egg albumin (EA). Their detection limits ( S/ N=3) are 2.1×10 −8, 2.5×10 −8 and 5.0×10 −8 g ml −1, respectively. In addition, the interaction mechanism is also investigated.

Fluorimetric Study of the Interaction Between Heparin and Norfloxacin‐Terbium Complex and its Application

A new spectrofluorimetric method was developed for determination of trace amounts of heparin (Hep). Using norfloxacin (NFLX)‐terbium (Tb3+) as a fluorescent probe, in the buffer solution of pH = 7.2, Hep can remarkably enhance the fluorescence intensity of the NFLX‐Tb3+ complex at λ = 545 nm. The enhanced fluorescence intensity of Tb3+ ion is in proportion to the concentration of Hep. Optimum conditions for the determination of Hep were also investigated. The dynamic range for the determination of Hep is 0.03–1.5 µg · mL−1 with detection limit of 51.04 ng · mL−1. This method is simple, practical, and relatively free of interference from coexisting substances, and it can be successfully applied to determination of Hep in heparin sodium injection samples. By the Rosenthal graphic method, the association constant and binding numbers of heparin with the probe are 1.09 × 104 L · mol−1 and 21.34. Moreover, the enhancement mechanisms of the fluorescence intensity in the NFLX‐Tb3+ system and the NFLX‐Tb3+‐Hep system have also been discussed.