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1.
In our study, terbium-acetylacetone (Tb-acac) composite nanoparticles have been prepared under vigorous ultrasonic irradiation.
The nanoparticles are water soluble, stable and have extremely narrow emission bands and high internal quantum efficiencies.
They were used as fluorescence probes in the determination of enoxacin (Enox) based on the fluorescence enhancement of nanoparticles
through fluorescence resonance energy transfer (FRET). The influence of buffer solution on the fluorescence intensity was
investigated. Under the optimum conditions, the fluorescence intensity of the Tb-acac-Enox system is linearly proportional
to the Enox concentration in the Enox concentration range of 2 × 10−7–1 × 10−4 M. The correlation coefficient for the calibration curve was 0.9976. The limit of detection as defined by IUPAC, C
LOD = 3S
b/m (where S
b is the standard deviation of the blank signals and m is the slope of the calibration graph) was found to be 3 × 10−8 M. The relative standard deviation (RSD) for six repeated measurements of 1 × 10−4 M Enox was 1.35%. The method was applied to the determination of Enox in pharmaceutical formulation and recovery results
were obtained from urine samples. 相似文献
2.
Study on the New Fluorescence Enhancement System of Tb –N-(2 - Pyridinyl) Ketoacetamide-Et<Subscript>3</Subscript>N-Zn and its Application 总被引:1,自引:0,他引:1
A sensitive fluorescence enhancement system was developed for the determination of zinc (II). The fluorescence intensity of
the Tb- N- (2 - Pyridinyl) ketoacetamide (PKA) system was greatly enhanced by the addition of triethylamine (Et3N) and zinc nitrate in the methanol solution. The excitation and emission wavelengths were 329 nm and 546 nm, respectively.
Under optimal conditions, the fluorescence intensities varied linearly with the concentration of Zn2+ in the range of 8.0×10−7−5.0×10−6 M with a detection limit of 9.9×10−8 M. The interferences of some substances were described. This method was applied to the determination of amounts of Zn2+ in soybean, rice, and wheat, respectively. The results showed that the proposed procedure is a high selective, simple, and
rapid method to the determination of Zn2+ ion. The mechanism of fluorescence enhancement was also studied. 相似文献
3.
A new spectrofluorimetric method was developed for the determination of trace amounts of dopamine (DA). Using chlorosulfonylthenoyltrifluoroacetone
(CTTA)–europium ion (Eu3+) as a fluorescent probe, in a buffer solution at pH = 10.0, DA can remarkably enhance the fluorescence intensity of the CTTA-Eu3+ complex at λ = 612 nm; the enhanced fluorescence intensity of Eu3+ is proportional to the concentration of DA. Optimum conditions for the determination of DA were also investigated. The linear
range and detection limit for the determination of DA were 5.0 × 10−8∼1.6 × 10−5 mol/l and 3.2 × 10−8 mol/l. This method is simple, practical and relatively free of interference from coexisting substances, and can be applied
to assess DA in injection and human serum samples with good precision and accuracy. 相似文献
4.
A selective fluorescent cesium optode on a chromoionophore consisting of anthracene covalently linked through an imine bond
to a 15-crown-5 derivative has been reported. In the present system, 15-crown-5 derivative including anthracene was used a
fluoroionophore. The fluorescence response mechanism is based on the photo-induced electron transfer (PET) from the lone pair
of electrons of the nitrogen to the anthracene group and inhibition of PET system by cesium binding while increasing the fluorescence
intensity. Emission intensity 15-crown-5 anthracene was measured at 500 nm with absorbance at 400 nm in CH3CN–H2O (1:1) media. The method shows a very good selectivity and sensitivity for cesium with respect to other cations such as K+, Na+ and Li+ with linear range and detection limit of 5.0 × 10−5 to 5.0 × 10−1M and 3.0 × 10−6M respectively. 相似文献
5.
A new quantitative method for micro amounts of nucleic acids in aqueous solution is proposed using Eu3+-benzoylacetone (BA) complex as fluorescent probe in the presence of cetyltrimethyl-ammonium bromide (CTMAB). Under the optimum
condition, the ratio of the fluorescence intensities with and without nucleic acids is proportional to the concentration of
nucleic acid in the range of 1.0 × 10−9 to 5.0 × 10−6 g/mL for herring sperm DNA (hsDNA), 3.0 × 10−9 to 1.0 × 10−6 g/mL for calf thymus DNA(ctDNA) and 8.0 × 10−9 to 1.0 × 10−6 g/mL for yeast RNA (yRNA), and their detection limits are 0.33, 0.21 and 0.99 ng/mL, respectively. Actual sample (DNA of
Arabidopsis thaliana) was determined satisfactorily. In addition, the interaction mechanism is also investigated. 相似文献
6.
A sensitive and selective method for the trace determination of 3, 3’, 4, 4’-tetrachlorobiphenyl (PCB77) by using bovine serum
albumin (BSA) as a fluorescence probe was introduced. Under optimum conditions, the enhanced fluorescence intensity was proportional
to the concentration of polychlorinated biphenyls in the range of 8.9 × 10−8–5.0 × 10−6 mol L−1 for PCB77, and 5.0 × 10−7–5.0 × 10−6 mol L−1 for 2, 2’, 5, 5’-tetrachlorbiphenyl (PCB52). The detection limits (S/N = 3) of PCB77 and PCB52 were 2.6 × 10−8 mol L−1 and 2.9 × 10−7 mol L−1, respectively. Furthermore, the fluorescence enhancement mechanism was discussed in detail. Results indicated that fluorescence
enhancement of the system originated from the formation of BSA-PCBs complexes. In addition, PCBs were mainly bound to the
tyrosine residues in BSA molecules. 相似文献
7.
Yoshio Kobayashi Hidekazu Kakinuma Daisuke Nagao Yasuo Ando Terunobu Miyazaki Mikio Konno 《Journal of nanoparticle research》2009,11(7):1787-1794
This article describes a method for silica coating of Co–Pt alloy nanoparticles prepared in the presence of poly(vinylpyrrolidone)
(PVP) as a stabilizer. The Co–Pt nanoparticles were prepared in an aqueous solution at 25–80 °C from CoCl2 (3.0 × 10−4 M), H2PtCl6 (3.0 × 10−4 M), PVP (0–10 g/L), and NaBH4 (4.8 × 10−3–2.4 × 10−2 M). The silica coating was performed for the Co–Pt nanoparticle colloid containing the PVP ([Co] = [Pt] = 3.0 × 10−5 M) at 25 °C in (1/4) (v/v) water/ethanol solution with tetraethoxyorthosilicate (TEOS) (7.2 × 10−5–7.2 × 10−3 M) and ammonia (0.1–1.0 M). Silica particles, which had an average size of 43 nm and contained multiple cores of Co–Pt nanoparticles
with a size of ca. 8 nm, were produced at 1.4 × 10−3 M TEOS and 0.5 M ammonia after the preparation of Co–Pt nanoparticles at 80 °C, 5 g/L PVP, and 2.4 × 10−2 M NaBH4. Their core particles were fcc Co–Pt alloy crystallites. Their saturation magnetization was 2.0-emu/g sample, and their coercive
field was 12 Oe. 相似文献
8.
It is found that silver nanoparticles (AgNPs) can further enhance the fluorescence intensity of curcumin (CU) - cetyltrimethylammonium
bromide (CTAB) – nucleic acids and improve its anti-photobleaching activity. Under optimum conditions, the enhanced fluorescence
intensity is proportion to the concentration of nucleic acids in the range of 2.0 × 10−8–1.0 × 10−6 g mL−1 for fish sperm DNA (fsDNA), 2.0 × 10−8–1.0 × 10−6 g mL−1 for calf thymus DNA (ctDNA), 1.0 × 10−8–1.0 × 10−6 g mL−1 for yeast RNA (yRNA), and their detection limits (S/N = 3) are 8.0 ng mL−1, 10.5 ng mL−1 and 5.8 ng mL−1, respectively. This method is used for determining the concentration of DNA in actual sample with satisfactory results. The
interaction mechanism is also studied. 相似文献
9.
The interaction between thyroxine hormone and 7 hydroxycoumarin (7HC) was investigated using fluorescence quenching method.
The experimental results showed that thyroxine could quench the fluorescence of 7HC by forming the 7HC–thyroxine complex with
static quenching. The apparent binding constants (K) between 7HC and thyroxine were determined to be 1.51 × 104 (297 K) and 9.06 × 103 (310 K). The binding sites (n) 0.98 ± 0.1. The thermodynamic parameters showed that the interaction between 7HC and thyroxine was driven mainly by hydrogen
bonding interactions and van der Waals force. Calibration for thyroxine, based on quenching titration data, was linear in
the concentration range 2.0 × 10−8 to 3.0 × 10−7 mol/l. The relative standard deviation was 2.58% for 2.0 × 10−7 mol/l thyroxine (n = 4) and the 3σ limit of detection was 3.42 × 10−8 mol/l in cationic surfactant CTAB medium. 相似文献
10.
A method to determine catechin in aqueous solution by measuring chemiluminescence intensities using a stopped flow system
has been studied. The lucigenin-hydrogen peroxide chemiluminescence reaction was chosen for the determination of catechin.
Fe(II) ion was added to the chemiluminescence system to increase the sensitivity. The chemiluminescence intensity from the
lucigenin system was increased by the addition of catechin. Effects of flow rates of reagent and sample and concentrations
of lucigenin, hydrogen peroxide, Fe(II) ion and KOH were investigated. The calibration curve for catechin was linear over
the range from 1.0×10−6 to 1.0×10−3 M and the detection limit was 3.0×10−7 M under the optimal experimental conditions. 相似文献
11.
A fluorescence enhancement phenomenon in the europium (Eu)–Ofloxacin (OF)–Sodium Dodecyl Benzene Sulfonate (SDBS) fluorescence
system was observed when Gd3+ was added. The fluorescence intensity of the systems was measured (λ
ex/λ
em = 280/612 nm) at pH 7.8. Under optimum conditions, a linear relationship between the enhanced fluorescence intensity and
the Eu3+ concentration in the range of 5.0 × 10−10 ∼ 2.0 × 10−7 mol·L−1 was observed. The detection limit of Eu3+ was 1.46 × 10−10 mol·L−1 (S/N = 3). This method was used for the determination of trace amounts of europium in synthetic rare earth samples with satisfactory
results. In addition, the interaction mechanism is also studied. 相似文献
12.
The fluorescence system of the norfloxacin-Tb3+- sodium dodecylbenzene sulfonate (SDBS) was investigated in this paper. The experiments indicated that the fluorescence intensity
of the Tb3+-SDBS was greatly enhanced by the norfloxacin. On the basis of the above findings, a sensitive fluorimetric method for determining
the norfloxacin was established. The fluorescence intensity was measured by a 1-cm quartz cell with the excitation wavelength
of 290 nm and the emission wavelength of 545 nm. The enhanced fluorescence intensity of the system (Δ F) showed a good linear
relationship with the concentration of norfloxacin in the range of 5.0×10−9 mol L−1–2.0×10−6 mol L−1, its correlation coefficient was 0.9991 and the detection limit (S/N=3) was 1.2×10−9 mol L−1. The presented method was used to determine the norfloxacin in real pharmaceutical samples. The luminescence mechanism was
also discussed in detail. In the fluorescence system of the norfloxacin-Tb3+-SDBS, the SDBS not only acted as the surfactant, but also acted as the energy donor. 相似文献
13.
Jeon CW Khan MA Lee SH Karim MM Lee HK Suh YS Alam SM Chung HY 《Journal of fluorescence》2008,18(5):843-851
A simple and selective method to determine norfloxacin using an optical flow-through sensor has been developed. The present
sensor was prepared by packing anionic ion exchange resin in a glass tube, followed by introducing KMnO4 solution to the glass tube for immobilization on resin. The optical sensor is based on the emission intensity from the Tb(III)
solution sensitized by norfloxacin. The excitation of norfloxacin occurred by the chemiluminescence from the reaction of KMnO4 and Na2SO4 solutions. The effects of pH, concentration of Tb(III) ion, KMnO4 and Na2SO4 solutions and flow rate of the norfloxacin solution on the chemiluminescence intensity were studied to find the optimum experimental
conditions. The emission intensity increased linearly with increasing norfloxacin concentration from 1.0 × 10−3 to 1.0 × 10−8 M and the detection limit (3σ) was 8.7 × 10−9. The applicability of the present method was demonstrated by determination of norfloxacin in various pharmaceutical preparations
and serum sample. 相似文献
14.
Based on the micelle synergism mechanism, a simple and sensitive flow injection chemiluminescence (FI-CL) method for the assay
of lornoxicam was described. The CL signal generated from the reaction of Ce (IV) with lornoxicam in acidic solution was very
weak, while the interfusion of sodium dodecyl benzene sulfonate (SDBS) resulted in a highly CL intensity. Under the optimum
experimental conditions, the CL intensity was proportional to lornoxicam concentration over the range 1.0 × 10−10–7.3 × 10−8 g/mL with a detection limit of 4.9 × 10−11 g/mL (3σ). The relative standard deviation for 11 replicate measurements of 3.0 × 10−9 g/mL of lornoxicam was 1.9%. The proposed method was successfully applied for the assay of lornoxicam in pharmaceuticals,
human serum and urine with excellent recovery. The possible mechanism of CL reaction was also discussed briefly. 相似文献
15.
The formation of a complex between ketoconazole and β-cyclodextrin was followed by spectrofluorimety. The inclusion of ketoconazole
in β-cyclodextrin cavity enhanced the native fluorescence of the drug. The stoichiometry of the complex was 1:1 β-cyclodextrin
to ketoconazole and the stability constant of the complex (log K
f) was determined to be 4.3 ± 0.01 at pH = 7.9 and 3.7 ± 0.04 at pH = 2.6. A sensitive spectrofluorimetric method for the detection
of ketoconazole is presented. At optimized experimental conditions, a linear relationship between the fluorescence intensity
of the solution and concentration of ketoconazole is observed in the range of 0.01–10 μg ml−1 (5 × 10−8 M–1.88 × 10−5 M). The method was applied to the detection of ketoconazole in pharmaceutical products and the results were satisfactory
in comparison to the official method (relative error = 2.8% and standard deviation = 0.06 for tablets of ketoconazole). The
recovery of ketoconazole from a blood serum sample, determined by the proposed method, was 97.1 ± 2.4%. 相似文献
16.
The serum albumin is the most abundant protein in blood plasma and the iron is essential for many cellular processes. However,
the interaction between Fe3+ and haem-free serum albumin remains unclear. Here we provide evidence for the fact that haem-free BSA possesses one specific
Fe3+-binding site. The binding of Fe3+ to BSA results in a significant quenching of the Trp fluorescence of BSA. The average apparent dissociation constant value
for the interaction of Fe3+ and BSA is 3.46 × 10−8 ± 3 × 10−10 M at 37 °C and 3.30 × 10−8 ± 5 × 10−10 M at 25 °C, respectively, as determined by fluorescence titration. Addition of 50 μM Fe2+ to 1 μM BSA results in an obvious hysteretic effect on the fluorescence of BSA. The time-dependent fluorescence quenching
of BSA by Fe2+ is not caused by the Fe2+-induced conformational change of BSA, but the oxygen-dependent oxidation of Fe2+ to Fe3+. Fe2+ undergoes an oxygen-dependent oxidation to Fe3+ under aerobic conditions, which is accelerated by the interaction of BSA with Fe3+ and extensively inhibited under anaerobic conditions. The results suggest that BSA may take part in non-transferrin bound
iron transfer. 相似文献
17.
A new spectrofluorimetric method was developed for the determination of trace amount of 5-hydroxytryptamine (5-HT) in human
urine and serum samples. In the NaAc-HAc buffer solution of pH=5.80, 5-HT can react with formaldehyde-acetylacetone system
to form a new compound which sends yellow green fluorescence at 533nm and the enhanced fluorescence intensity is in proportion
to the concentration of 5-HT. Optimum conditions for the determination of 5-HT were also investigated. The dynamic range and
detection limit for the determination of 5-HT are 5.35×10−7∼1.07×10−4 mol/L and 2.08×10−7 mol/L, respectively. The developed method is simple, practical and can be successfully applied to determination of 5-HT in
human urine and serum samples. Moreover, the enhancement mechanisms of the fluorescence intensity in the 5-HT - formaldehyde-acetylacetone
system have been also discussed. 相似文献
18.
A fluorescent assay of Hg2+ in neutral aqueous solution was developed using N-[p-(dimethylamino)benzamido]-N′-phenylthiourea (1). 1’s fluorogenic chemodosimetric behaviors towards various metal ions were studied and a high sensitivity
as well as selectivity was achieved for Hg2+. It was because of a strongly fluorescent 1,3,4-oxadiazoles which was produced by the Hg2+ promoted desulfurization reaction. The spectra of ESI mass and IR provided evidences for this reaction. According to fluorescence
titration, a good linear relationship ranging from 1.0 × 10−7 to 2.0 × 10−5 mol l−1 was obtained with the limit of detection as 3.1 × 10−8 mol l−1.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
L-Cysteine capped CdTe nanoparticles (NPs) were synthesized in aqueous medium, and their application as fluorescence probes
in the determination of paracetamol was studied. The L-cysteine capped CdTe NPs were characterized by transmission electron
microscopy, X-ray diffraction spectrometry, spectrofluorometry, ultraviolet-visible and Fourier transform infrared spectrometry.
Based on the distinct fluorescence quenching of CdTe fluorescence probes in the presence of paracetamol, a simple, rapid and
specific method for paracetamol determination was presented. Under optimum conditions, the relative fluorescence intensity
of CdTe NPs was linearly proportional to paracetamol concentration from 1.0 × 10−8 mol/L to 1.6 × 10−7 mol/L with a detection limit of 4.2 × 10−9 mol/L. The proposed method was applied to detect paracetamol in commercial tablets with satisfactory results. 相似文献
20.
In this paper we reported a metal complex 1-Zn (2,5-di-[2-(3,5-bis(2-pyridylmethyl)amine-4-hydroxy-phenyl)-ethylene]-pyrazine-Zn) as a fluorescent probe sensing DNA. The
result of the competitive experiment of the probe with ethidium bromide (EB) to bind DNA, absorption spectral change and polarization
change in the presence and absence of DNA revealed that interaction between the probe and DNA was via intercalation. Ionic
strength experiment showed the existence of electrostatic interaction as well. Scatchard plots also confirmed the combined
binding modes. The fluorescence enhancement of the probe was ascribed to highly hydrophobic environment when it bound the
macromolecules such as DNA, RNA or denatured DNA. The binding constant between the probe and DNA was estimated as 3.13 × 107 mol−1 L. The emission intensity increase was proportional to the concentration of DNA. Based on this, the probe was used to determine
the concentration of calf thymus DNA (ct-DNA). The corresponding linear response ranged from 2.50 × 10−7 to 4.75 × 10−6 mol L−1, and detection limit was 1.93 × 10−8 mol L−1 for ct-DNA. 相似文献