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1.
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
2.
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
3.
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
4.
In this paper, we reported the syntheses and investigation of the modes of binding to DNA of the two new ethidium derivatives
containing benzoyl and phenylacetyl groups of both amines at 3-and 8- positions. The interactions between calf thymus DNA
(ct-DNA) and the two derivatives, 3,8-dibenzoylamino-5-ethyl-6-phenylphenantridinium cloride (E2) and 3,8-diphenylacetylamino-5-ethyl-6-phenylphenantridinium chloride (E3), were investigated by fluorescence quenching spectra and UV-vis absorption spectra. The Stern-Volmer quenching constants,
binding constants, binding sites and the corresponding thermodynamic parameters ΔH, ΔS and ΔG were calculated at different
temperatures. The results indicated the formation of E2 and E3-DNA complexes and van der Waals interactions as the predominant intermolecular forces in stabilizing for each complex. In
addition, increasing nucleophilicity of the functional groups at 3- and 8- positions exhibited the respectable increment the
DNA binding affinities of derivatives. The results of absorption, ionic strength and iodide ion quenching suggested that the
interaction mode of E2 and E3 with ct-DNA was intercalative binding. The limit of detection (LOD) of ct-DNA were 7.49 × 10−8 (n = 4) and 4.18 × 10−8 mol/l (n = 7) in presence of E2 and E3, respectively. 相似文献
5.
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
6.
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
7.
A novel fluorescence quenching method for the determination of Vitamin B12(VB12) had been developed. It was based on that the fluorescence intensity of erythrosine sodium(ES) could be enhanced by Hydroxypropyl-β-cyclodextrin(HP-β-CD)
due to the formation of inclusion complex (HP-β-CD-ES), while the fluorescence intensity of HP-β-CD-ES was diminished after
adding VB12 into the system, and there was a linear relationship between the fluorescence quenching value of the system (ΔF) and the
concentration of VB12(c). The mechanism of the determination of VB12was discussed. The results showed that under the optimal conditions, the linear range of calibration curve for the determination
of VB12 was 0.0∼2.1 × 10−5 mol/L, and the detection limit was 1.8×10−7 mol/ L. It could be satisfactorily applied to the determination of VB12 in injections. 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 binding of quercetin to lysozyme (LYSO) in aqueous solution was investigated by fluorescence spectroscopy, UV-vis absorption
spectroscopy and molecular simulation at pH 7.4. The fluorescence quenching of LYSO by addition of quercetin is due to static
quenching, the binding constants, K
a
, were 3.63 × 104, 3.31 × 104 and 2.85 × 104 L·mol−1 at 288, 298 and 308 K, respectively. The thermodynamic parameters, enthalpy change, ∆H, and entropy change, ∆S, were noted to be −7.56 kJ·mol−1 and 61.07 J·mol−1·K−1. The results indicated that hydrophobic interaction may play a major role in the binding process. The distance r between the donor (LYSO) and acceptor (quercetin) was determined as 3.34 nm by the fluorescence resonance energy transfer.
The synchronous fluorescence spectroscopy showed the polarity around the tryptophan residues increased and the hydrophobicity
decreased. Furthermore, the study of molecular simulation indicated that quercetin could bind to the active site (a pocket
made up of 24 amino-acid residues) of LYSO mainly via hydrophobic interactions and that there were hydrogen interactions between
the residues (Gln 57, Ile 98) of LYSO and quercetin. The accessible surface area (ASA) calculation verified the important
roles of tryptophan (Trp) residues during the binding process. 相似文献
10.
CdHgTe nanoparticles (NPs) with the emission in the near-infrared regions were prepared in aqueous solution, and were characterized
by transmission electron microscopy, X-ray diffraction spectrometry, spectrofluorometry and ultraviolet-visible spectrometry.
Based on the fluorescence quenching of CdHgTe NPs in the presence of proteins, a novel method for the determination of proteins
with CdHgTe NPs as a near-infrared fluorescence probe was developed. Maximum fluorescence quenching was observed with the
excitation and emission wavelengths of 500 and 693 nm, respectively. Under the optimal conditions, the calibration graphs
were linear in the range of 0.04 × 10−6–5.6 × 10−6 g ml−1 for lysozyme (Lyz) and 0.06 × 10−6–6.1 × 10−6 g ml−1 for bovine hemoglobin (BHb), respectively. The limits of detection were 13 ng ml−1 for Lyz and 27 ng ml−1 for BHb, respectively. Four synthetic samples were determined and the results were satisfied. 相似文献
11.
Hosseini M Ganjali MR Tavakoli M Norouzi P Faridbod F Goldooz H Badiei A 《Journal of fluorescence》2011,21(4):1509-1513
A novel and simple fluorescence enhancement method for selective pyrophosphate(PPi) sensing was proposed based on a 1:1 metal
complex formation between bis(8-hydroxy quinoline-5-solphonat) chloride aluminum(III) (Al(QS)2Cl), (L) and PPi in aqueous solution. The linear response range covers a concentration range of 1.6 × 10−7 to 1.0 × 10−5 mol/L of PPi and the detection limit of 2.3 × 10−8 mol/L. The association constant of L-PPi complex was calculated 2.6 × 105 L/mol. L was found to show selectively and sensitively fluorescence enhancement toward PPi over than I3-, NO3-, CN−, CO32−, Br−, Cl−, F−, H2PO4− and SO42−, which was attributed to higher stability of inorganic complex between pyrophosphate and L. 相似文献
12.
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
13.
M.?Cristina?Gon?alves Verónica?de?Zea Bermudez M.?M.?Silva M.?J.?Smith Enrique?Morales Rute?A.?Sá Ferreira Luís?D.?Carlos 《Ionics》2010,16(3):193-201
Variable chain length di-urethane cross-linked poly(oxyethylene) (POE)/siloxane hybrid networks were prepared by application
of a sol-gel strategy. These materials, designated as di-urethanesils (represented as d-Ut(Y′), where Y′ indicates the average
molecular weight of the polymer segment), were doped with lithium triflate (LiCF3SO3). The two host hybrid matrices used, d-Ut(300) and d-Ut(600), incorporate POE chains with approximately 6 and 13 (OCH2CH2) repeat units, respectively. All the samples studied, with compositions ∞ > n ≥ 1 (where n is the molar ratio of (OCH2CH2) repeat units per Li+), are entirely amorphous. The di-urethanesils are thermally stable up to at least 200 °C. At room temperature the conductivity
maxima of the d-Ut(300)- and d-Ut(600)-based di-urethanesil families are located at n = 1 (approximately 2.0 × 10−6 and 7.4 × 10−5 Scm−1, respectively). At about 100 °C, both these samples also exhibit the highest conductivity of the two electrolyte systems
(approximately 1.6 × 10−4 and 1.0 × 10−3 Scm−1, respectively). The d-Ut(600)-based xerogel with n = 1 displays excellent redox stability. 相似文献
14.
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
15.
A novel, simple, sensitive and selective spectrofluorimetric method was developed for the determination of trace amounts of
chlorzoxazone and Ibuprofen in pharmaceutical tablets using optical sensor Eu-Tetracycline HCl doped in sol–gel matrix. The
chlorzoxazone or Ibuprofen can remarkably enhance the luminescence intensity of Eu-Tetracycline HCl complex doped in a sol–gel
matrix in dimethylformamide (DMF) at pH 9.7 and 6.3, respectively, λex = 400 nm. The enhancing of luminescence intensity peak of Eu-Tetracycline HCl complex at 617 nm is proportional to the concentration
of chlorzoxazone or Ibuprofen a result that suggested profitable application as a simple optical sensor for chlorzoxazone
or Ibuprofen assessment. The dynamic ranges found for the determination of chlorzoxazone and Ibuprofen concentration are 5 × 10−9–1 × 10−4 and 1 × 10−8–7 × 10−5 mol L−1, and the limit of detection (LOD) and quantitation limit of detection (LOQ) are 3.1 × 10−10 , 9.6 × 10−10 and 5.6 × 10−10, 1.7 × 10−9 mol L−1, respectively. 相似文献
16.
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
17.
The saccharide binding and conformational characterization of a hemagglutinin, a low molecular weight protein from the seeds
of Moringa oleifera was studied using steady state and time resolved fluorescence. The lectin binds sugars LacNAc (K
a = 1380 M−1) and fructose (K
a = 975 M−1), as determined by the fluorescence spectroscopy. It has a single tryptophan per monomer which is exposed on the surface
and is in a strong electropositive environment as revealed by quenching with iodide. Quenching of the fluorescence by acrylamide
involved both static (K
s = 0.216 M−1) and collisional (K
sv = 8.19 M−1) components. The native protein showed two different lifetimes, τ
1 (1.6 ns) and τ
2 (4.36 ns) which decrease and get converted into a single one, (2.21 ns) after quenching with 0.15 M acrylamide. The bimolecular
quenching constant, k
q
was 7.55 × 1011 M−1 s−1. ANS binding studies showed that the native protein has exposed hydrophobic patches which get further exposed at extreme
acidic or alkaline pH. However, they get buried in the interior of the protein in presence of 1 M GdnHCl or urea. 相似文献
18.
Attia MS Mahmoud WH Ramsis MN Khalil LH Othman AM Hashem SG Mostafa MS 《Journal of fluorescence》2011,21(4):1739-1748
A simple and sensitive spectrofluorimetric method for determination of trace amount of doxycycline hydrochloride (DC) in pharmaceutical
tablets and serum samples was developed. In ammonia buffer solution of pH 8.9 the doxycycline hydrochloride can remarkably
enhance the luminescence intensity of the Sm3+ ion in Sm3+- DC complex at λex = 400 nm. The produced luminescence intensity of Sm3+- DC complex in DMSO is in proportion to the concentration of DC and used as optical sensor for its determination. The dynamic
range for the determination of DC is 1 × 10−8 – 5 × 10−6 mol L−1 and in case of quantum yield calculations is 7 × 10−9 – 5 × 10−6 mol L−1 with detection limit of 6.5 × 10−10 mol L−1. The enhancement mechanism of the luminescence intensity in the Sm3+- DC system has been also discussed. A comparison with other spectrofluorimetric methods for tetracycline derivatives in which
Eu3+ ion is used instead of Sm3+ ion is also studied. 相似文献
19.
Marcolan M Martins PA Pedrosa VA Rodrigues MR de Oliveira HP Codognoto L 《Journal of fluorescence》2011,21(2):733-738
A simple, rapid and effective analytical method based on fluorescence spectroscopy for the determination of coumarin in pharmaceutical
formulations without pre-treatment or pre-concentration step was development. Coumarin had maximum excitation and emission
at 310 nm and 390 nm, respectively. Optimum conditions for the detection of coumarin were investigated. Under optimized conditions,
we observed a linear behavior for the sign of coumarin in the concentration range of 2.5 × 10−6 to 1.0 × 10−4 mol L−1, with linearity of 0.998 and sensitivity of 2.9 × 1010 u.a/mol L−1. The proposed method was validated in terms of accuracy, precision and specificity of coumarin using the standard addition
and external calibration. It was noted that the results support (P < 0.05), indicating that the matrices were not an interference in the determination of coumarin by fluorescence spectroscopy.
The results were favorable compared with those obtained by reference chromatographic methods. 相似文献
20.
Alonso A Almendral MJ Curto Y Criado JJ Rodríguez E Manzano JL 《Journal of fluorescence》2007,17(4):390-400
The flow injection technique is applied to study the binding to DNA of new platinum complexes—E1: ethylenediaminechlorocholylglycinateplatinum(II): [PtCl(CG)(en)], C54H92O12Pt and E2: ethylenediaminebischolylglycinateplatinum(II): [Pt(CG)2(en)], C28H50ClN3O6Pt—derived from cisplatin in which the exchangeable ligands were replaced by bile acids, such that these anticancer drugs
have less toxicity and less resistance is developed towards them. Both compounds are fluorescent and their fluorescence is
enhanced when they form adducts with DNA, a property that is extremely useful for monitoring the cytotoxic activity and their
mechanisms of action. The binding parameters to DNA of E1 [apparent intrinsic binding constant KE1: (11.2 ± 0.4) × 103 M−1 and maximum number of binding sites per nucleotide, n
E1: 0.121 ± 2 × 10−3) and E2 (KE2: 9.2 ± 0.7) × 103 M−1 and n
E2 0.098 ± 2 × 10−3] were determined following the Scatchard method and the type of binding was studied experimentally through the modifications
introduced by each of the compounds into the ethidium bromide–DNA bond. 相似文献