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1.
A novel fluorescence quenching method for the determination of tetracaine hydrochloride (TA·HCl) concentration with some aromatic
amino acids as fluorescence probe has been developed. In pH 6.3 acidic medium, tryptophane (Trp), tyrosine (Tyr) or phenylalanine
(Phe) can react with tetracaine hydrochloride to form an ion-association complex by electrostatic attraction, aromatic stacking
interaction and Van der Waals’ force, which lead to fluorescence quenching of above amino acids. The maximum fluorescence
excitation and emission wavelengths of them are located at 278, 274, 258 nm and 354, 306, 285 nm, respectively. The relative
fluorescence intensity (F
0/F) is proportional to the TA·HCl concentration in certain range. The linear ranges and detection limits are 1.2–5.0 μg/mL and
0.37 μg/mL for Tyr-TA·HCl system, 1.3–6.0 μg/mL and 0.38 μg/mL for Trp-TA·HCl system, and 1.4–6.0 μg/mL and 0.41 μg/mL for
Phe-TA·HCl system. The optimum reaction conditions, influencing factors and the effect of coexisting substances are investigated.
And the results show the method has a good selectivity. Judging from the effect of temperature, the Stern-Volmer plots and
fluorescence lifetime determination, the quenching of fluorescence of amino acids by TA·HCl is a static quenching process. 相似文献
2.
3.
荧光光谱法研究核黄素与核黄素结合蛋白的相互作用 总被引:1,自引:0,他引:1
运用荧光光谱研究了核黄素与核黄素结合蛋白的相互作用,并探讨了两者间的结合类型、结合常数、结合过程中热力学参数和能量转移。结果表明:核黄素结合蛋白内源荧光的猝灭是由于核黄素与蛋白质之间形成复合物,并符合静态猝灭机理。298,308,318K下核黄素与核黄素结合蛋白的结合常数分别为:5.35×108,1.54×108,0.56×108 L.mol-1。热力学数据表明核黄素与核黄素结合蛋白之间主要作用力为氢键和范德华力。Frster能量转移理论确定了核黄素与核黄素结合蛋白的作用距离与能量转移效率分别为0.70nm与0.39。利用同步荧光光谱研究了核黄素结合蛋白与核黄素结合过程中构象的变化。 相似文献
4.
Fengling Cui Qiangzhai Zhang Yinghua Yan Xiaojun Yao Guirong Qu Yan Lu 《Journal of Applied Spectroscopy》2008,75(5):743-751
The interactions of human (HSA) and bovine (BSA) serum albumins with 1-cyanoethyl-5-chlorouracil (CECU) were investigated
by fluorescence spectroscopy, UV absorption spectroscopy, and molecular modeling methods under the simulated physiological
conditions. The results of fluorescence measurements indicate that CECU has a strong ability to quench the intrinsic fluorescence
of both HSA and BSA through a static quenching procedure. The binding constants (K) at different temperatures and thermodynamic
parameters, enthalpy change (ΔH), and entropy change (ΔS) were calculated according to fluorescence data. The results show
that hydrophobic interaction is a predominant intermolecular force for stabilizing the complex, which is in agreement with
the results of molecular modeling study. The effect of some normal ions on the binding constants is also discussed.
Published in Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 737–745, September–October, 2008. 相似文献
5.
M. Putkiranta A. Manninen A. Rostedt J. Saarela T. Sorvaj?rvi M. Marjam?ki R. Hernberg J. Keskinen 《Applied physics. B, Lasers and optics》2010,99(4):841-851
Several fluorophores, such as tryptophan, NADH, NADPH, and riboflavin are found in airborne micro-organisms. In this work,
the fluorescence properties of these biochemicals were studied both in dry NaCl composite aerosol particles and in saline
solutions by means of laser-induced fluorescence. Fluorescence spectra were measured from individual, airborne aerosol particles
and from solutions in cuvette. The excitation wavelength was varied in steps from 210 nm to 419 nm and the fluorescence was
detected within a wavelength band of 310–670 nm. For each sample, the measured fluorescence emission spectra were combined
into fluorescence maps. The fluorescence maximum of riboflavin in a dry NaCl composite particle is 20 nm red-shifted compared
with the solution, whereas the maxima are blue-shifted by about 25 nm for tryptophan and 15 nm for NADH and NADPH. The molecular
fluorescence cross sections have significant differences between the aerosol particles and the solutions, except for tryptophan.
For NADH and NADPH the cross sections are over 20 times larger in the aerosol particles than in the solutions probably as
a result of partial quenching of fluorescence in solution caused by the collision or stacking with the adenine moiety. The
fluorescence cross section of riboflavin is almost 60 times larger in the solution than in the dry NaCl composite aerosol.
This is probably caused by the different microenvironment around the fluorophore molecule and by the concentration quenching
in the particles where the fluorescing molecules are relatively close to each other. 相似文献
6.
N. N. Kruk A. S. Starukhin N. Zh. Mamardashvili V. B. Sheinin Yu. B. Ivanova 《Journal of Applied Spectroscopy》2007,74(6):831-837
We have studied quenching of the fluorescence of the diprotonated form of 3,7,13,17-tetramethyl-2,8,12,18-tetrabutylporphyrin
by iodide ions in solutions. We have established that there is both static quenching of fluorescence when nonfluorescent complexes
are formed with the iodide ions, as a result of an internal heavy atom effect, and also dynamic diffusion-controlled quenching.
Based on analysis of the dependences of the fluorescence intensity and fluorescence lifetime on the iodide ion concentration
in solution, we suggest using the diprotonated form of this porphyrin as the base compound for designing a fluorescent molecular
receptor for halide ions.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 6, pp. 750–755, November–December, 2007. 相似文献
7.
1-(4-Aminoantipyrine)-3-tosylurea (H2L) and its three lanthanide (III) complexes, M(H2L)3 3NO3 [where M = Nd(III), Sm(III) and Eu(III)], have been synthesized and characterized. In addition, the DNA-binding properties
of the three complexes have been investigated by UV–vis (ultraviolet and visible) absorption spectroscopy, fluorescence spectroscopy,
circular dichroism (CD) spectroscopy, cyclic voltammetry, and viscosity measurements. Results suggest that the three complexes
bind to DNA via a groove binding mode. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the metal
complexes was determined by using spectrophotometer methods in vitro. These complexes were found to possess potent antioxidant
activity and be better than standard antioxidants like vitamin C and mannitol.
Absorption spectra of the complex 3 inTris-HCl buffer upon addition of calf-thymus DNA. [complex]=1×10-5 M, [DNA]=(0-1) ×10-5 M. Arrow shows the absorbance changing upon increasing DNA concentrations. Inset: plots of [DNA]/(εa – εf) versus [DNA] for the titration of DNA with the complex. 相似文献
8.
The quenching of 2,5-diphenyloxazole (PPO) fluorescence by nucleotides has been investigated by electronic absorption and
steady state fluorescence spectra. Five purine nucleotides AMP, ADP, ATP, GMP and dGMP, one pyrimidine nucleotide UMP and
one dinucleotide NAD have been employed in the present study. Electronic absorption studies indicate that there is no ground
state complexation between the nucleotides and PPO. The quenching of PPO fluorescence was investigated at two different wavelengths.
When excited at 304 nm, the λ
max of PPO, the fluorescence spectra of PPO is quenched following Stern–Volmer kinetics. The quenching ability of nucleotides
are in the order NAD > AMP > ADP > GMP > dGMP > UMP. The K
SV and k
q values obtained indicate that AMP is a better quencher of PPO fluorescence than GMP, which is contrary to commonly observed
pattern. The quenching is found to be dynamic in nature. However, when excited at 260 nm, the absorption maximum of the nucleotides,
the fluorescence intensity of PPO is reduced with increase in the concentration of the nucleotide. This is attributed to the
primary inner filter effect arising due to the absorption of the incident radiation by the nucleotides. Thus the inner filter
effect phenomenon can be employed to assay the non-fluorescent molecules by fluorimetry. 相似文献
9.
Luminescent CdS quantum dots capped with thioglycolic acid (CdS-TGA QDs) were demonstrated to serve as a fluorescence probe
for a model organic radical, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•), employing the quenching of the CdS-TGA QDs emission signal by the radical. Under the optimum conditions, the quenching
efficiency of DPPH• on CdS-TGA QDs was proportional to the concentration of DPPH•, following Stern-Volmer relationship. Different types of surfactants (cationic, anionic and neutral surfactants) were introduced
to CdS-TGA QDs in order to increase the detection sensitivity. The fluorescence intensity of CdS-TGA QDs was greatly enhanced
by cationic and neutral surfactants. Moreover, the quenching efficiency of DPPH• on the QDs in the presence of micelles was remarkably ca. 13 times higher than that in the system without micelles. Effects
of pH and concentration of surfactants on the fluorescence quenching of CdS-TGA QDs were investigated. Electron spin resonance
(ESR) spectroscopy was also used to monitor the DPPH radical species in CdS-TGA QDs mixtures with and without micelles. Fluorescence
quenching mechanisms of CdS-TGA QDs by DPPH• in the presence and in the absence of CTAB were proposed. 相似文献
10.
The photo—physical properties of N-(2-methylthiophenyl)-2-hydroxy-1-naphthaldimine (NMTHN) on silver nano particles have been
investigated using optical absorption and fluorescence emission techniques. Silver nanoparticles of different sizes have been
prepared by two different methods. The increases in size of the silver nanoparticles cause a decrease in the quenching of
fluorescence of NMTHN. Stern–Volmer quenching constants and the association constants have also been calculated. 相似文献
11.
Mahalingam Umadevi N. A. Sridevi A. S. Sharmila Beulah J. M. Rajkumar M. Briget Mary P. Vanelle T. Terme O. Khoumeri 《Journal of fluorescence》2010,20(1):153-161
Size effect of silver nano particles on the photophysical properties of 2,3-bis(chloromethyl)anthracene-1,4,9,10-tetraone
(BCMAT) have been investigated using optical absorption and fluorescence emission techniques. Silver NPs of different sizes
have been prepared by two different methods. Quenching of fluorescence of BCMAT has been found to increase with decrease in
the size of the silver NPs. Stern–Volmer quenching constants have also been calculated. 相似文献
12.
Using as an example the concentration dependence of the fluorescence quenching constants for quenching by Cd2+ ions for different weight fractions of humic acid, we have demonstrated the application of the fluorescence quenching method
for studying the effect of association on the structure of humic acids. We have established that the quenching constants for
the light fraction (5–30 kD) decrease as the humic acid concentration increases and the quenching constants increase for the
heavy fraction (60–100 kD). The observed dependences are interpreted in terms of the idea of oppositely directed effects of
association on the structure of the environment of fluorophores located within the core and peripheral regions of the humic
acid macromolecule. 相似文献
13.
The interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH●) free radical with thiol-capped CdTe quantum dots (QDs) has been studied by UV–vis spectroscopy, steady state and time resolved
fluorescence measurements. Addition of DPPH● radical to CdTe QDs resulted in fluorescence quenching. The interaction occurs through static quenching as this was confirmed
by fluorescence lifetime measurements. Time course absorption studies indicates that DPPH● may be reduced by interaction with QDs to the substituted hydrazine form (2,2-diphenyl-1-picrylhydrazine) DPPH-H. The mechanism
of fluorescence quenching of CdTe QDs by DPPH● is proposed. 相似文献
14.
Size effect of silver nano particles on the photophysical properties of 1,4-dihydroxy-2,3-dimethyl-9,10-anthraquinone (DHDMAQ)
have been investigated using optical absorption and fluorescence emission techniques. Silver nanoparticles of different sizes
have been prepared by Creighton method using magnetic stirrer and ultrasonic field. Quenching of fluorescence of DHDMAQ has
been found to increase with decrease in the size of the silver nanoparticles. Stern–Volmer quenching constants have also been
calculated. 相似文献
15.
16.
A novel Schiff base ligand, chromone-3-carbaldehyde-aminophenazone (L) and its Ln(III) (Ln = La, Yb) complexes were synthesized
and characterized by physicochemical methods. The interaction between the ligand, Ln(III) complexes and calf thymus DNA in
physiological buffer (pH = 7.10) was investigated by using UV–vis spectroscopy, fluorescence spectra, ethidium bromide experiments
and viscosity measurements, indicating that the studied compounds can all bind to DNA via an intercalation binding mode and
the complexes have stronger binding affinity than the free ligand alone. Furthermore, antioxidant activity of the ligand and
its complexes was determined by superoxide and hydroxyl radical scavenging methods in vitro, suggesting that Ln(III) complexes
inhibit stronger antioxidant activity than the ligand alone and some standard antioxidants, such as mannitol and vitamin C. 相似文献
17.
A novel Schiff-base ligand (H5L), hesperetin-2-hydroxy benzoyl hydrazone, and its copper (II), zinc (II) and nickel (II) complexes (M·H3L) [M(II) = Cu, Zn, Ni], have been synthesized and characterized. The ligand and Zn (II) complex exhibit green and blue fluorescence
under UV light and the fluorescent properties of the ligand and Zn (II) complex in solid state and different solutions were
investigated. In addition, DNA binding properties of the ligand and its metal complexes have been investigated by electronic
absorption spectroscopy, fluorescence spectra, ethidium bromide displacement experiments, iodide quenching experiments, salt
effect and viscosity measurements. Results suggest that all the compounds bind to DNA via an intercalation binding mode. Furthermore,
the antioxidant activity of the ligand and its metal complexes was determined by superoxide and hydroxyl radical scavenging
methods in vitro. The metal complexes were found to possess potent antioxidant activity and be better than the free ligand
alone and some standard antioxidants like vitamin C and mannitol. 相似文献
18.
The non-catalytic COOH-terminal module formed after proteolytic cleavage of full-length mammalian tyrosyl-tRNA synthetase displays dual function: tRNA binding ability and cytokine activity. With the aim to explore the intramolecular dynamics of C-module in solution we used fluorescence spectroscopy to study conformational changes of isolated protein. We used information from fluorescence spectra and computational model for characterization of a microenvironment of a single tryptophan residue (Trp144). Its fluorescence parameters and protection from quenching by Cs+ ions indicate the internal localization—buried into protein globule. The fluorescence quenching of Trp144 by acrylamide suggests rapid conformation dynamics of the C-module in nanosecond time scale. The temperature-induced conformational changes in the C-module were monitored by the fluorescence measurements of Trp144 emission and by red-edge excitation shift. An emission maximum shift up to ∼349 nm and significant decrease of the red-edge shift effect at 37–52 °C indicated a major conformational transition of Trp144 from buried native state into highly relaxing polar solvent environment. 相似文献
19.
S. K. Mehta Savita Chaudhary Sanjay Kumar Sukhjinder Singh 《Journal of nanoparticle research》2010,12(5):1697-1709
This article demonstrates the influence of various surfactants of different polarities—anionic, sodium dodecyl sulfate, cationic,
hexadecyltrimethylammonium bromide and non-ionic, and polyoxyethylene iso-octyl phenyl ether (TX-100)—on the formation of
CdSe nanoparticles in aqueous solutions. The surfactant-stabilizing effect has been monitored using transmission electron
microscopy. Spectral properties of CdSe nanoparticles have been investigated; the structure of the long-wave edge of the fundamental
absorption band of CdSe nanoparticles has been analyzed. It has been shown that the variation of the synthesizing conditions
(stabilizer’s nature and concentration, CdSe concentration, etc.) allows the tailoring of the CdSe nanoparticle size in the
range of 8–17 nm. Lifshitz–Slyrzov–Wagner kinetic analysis has also been performed using the size variation according to ripening
temperature and time period. The differences in the stabilization ability of tested substances are discussed with respect
to their structure and possible mechanism of the surface interaction with the nanoparticles. The flexible surface chemistry
of the CdSe-micelles causes them to be water soluble and allows their further conjugation with protein molecules through electrostatic
attraction. The interaction between functionalized CdSe nanoparticles with protein molecules have been investigated using
fluorescence spectroscopy. 相似文献
20.
We have prepared, characterized and investigated a new PEG-2000 based solid polymer electrolyte (PEG)
x
NH4I. Ionic conductivity measurements have been made as a function of salt concentration as well as temperature in the range
265–330 K. Selected compositions of the electrolyte were exposed to a beam of 8 MeV electrons to an accumulated dose of 10
kGy to study the effect on ionic conductivity. The electrolyte samples were also quenched at liquid nitrogen temperature and
conductivity measurements were made. The ionic conductivity at room temperature exhibits a characteristic double peak for
the composition x = 20 and 70. Both electron beam irradiation and quenching at low temperature have resulted in an increase in conductivity
by 1–2 orders of magnitude. The enhancement of conductivity upon irradiation and quenching is interpreted as due to an increase
in amorphous region and decrease in crystallinity of the electrolyte. DSC and proton NMR measurements also support this conclusion.
相似文献