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31.
Raut S Heck A Vishwanatha J Sarkar P Mody A Luchowski R Gryczynski Z Gryczynski I 《Journal of photochemistry and photobiology. B, Biology》2011,102(3):241-245
The antioxidant properties of aminobenzamide cysteine (ABZ Cys) makes it a molecule that can potentially be used as a drug in oxidative stress related diseases and delivered in the form of a nanoparticles. Here we have studied the photo-physical properties of ABZ Cys, a fluorescent analogue of a popular antioxidant N-acetyl cysteine (NAC). We have compared ABZ Cys steady state and time-resolved fluorescence properties with its parent compounds anthranilic acid and anthranilamide in solution as well as in poly-vinyl alcohol (PVA) polymer films. ABZ Cys did not show any significant shift in absorption after entrapment in PVA film, but there was a shift towards shorter wavelengths in the emission peak compared to the phosphate buffer solution. Fluorescence lifetimes and quantum yields indicated a slight quenching of ABZ Cys fluorescence in comparison to the cysteine-less parent compounds. We also demonstrated that very low concentrations of ABZ Cys, such as 100 nM, are readily detected by a commercial spectrofluorometer. Hence we have established the possible use of ABZ Cys in biomedical applications. 相似文献
32.
Simeonika Rangełowa‐Jankowska Dawid Jankowski Dr. Beata Grobelna Prof. Ignacy Gryczyński Prof. Zygmunt Gryczyński Dr. Robert Bogdanowicz Prof. Piotr Bojarski 《Chemphyschem》2011,12(13):2449-2452
The first observation of strong directional surface‐plasmon‐coupled emission (SPCE) of Rhodamine 110 in silica nanofilms deposited on silver nanolayers is reported. The preparation of the material is described in detail. The intensity of SPCE exceeds 10 times that of free space fluorescence and total linear light polarization in the SPCE ring is observed. A new experimental setup and an original data collection method is presented. Our material completely preserves its fluorescence properties for at least eight months. 相似文献
33.
The spherical oil agglomeration of barite suspensions in the presence of surfactant and cosurfactant
Zygmunt Sadowski 《Colloids and surfaces. A, Physicochemical and engineering aspects》1993,80(2-3):147-152
The spherical agglomeration of barite particles using oil in the presence of both surfactant and cosurfactant was studied. It was found that the mineral suspension needed a critical surfactant concentration to initiate oil agglomeration. The addition of long-chain aliphatic alcohols to the organic phase decreased the critical surfactant concentration. This phenomenon was ascribed to a screening effect of alcohol molecules in the adsorption layer of surfactant. When sodium chloride was added to the solution the spherical agglomeration disappeared even though the surfactant adsorption at the barite/solution interface increased. It was concluded that the disappearance of oil agglomeration was caused by a bilayer of the surfactant which was formed on the barite surface. In the barite—surfactant—alcohol—oil—brine system the agglomeration process is only realized with the long-chain alcohols. This behaviour can be explained by microemulsion formation at the mineral/solution interface. 相似文献
34.
Joseph R. Lakowicz Henryk Cherek Józef Kuśba Ignacy Gryczynski Michael L. Johnson 《Journal of fluorescence》1993,3(2):103-116
This didactic paper summarizes the mathematical expressions needed for analysis of fluorescence anisotropy decays from polarized frequency-domain fluorescence data. The observed values are the phase angle difference between the polarized components of the emission and the modulated anisotropy, which is the ratio of the polarized and amplitude-modulated components of the emission. This procedure requires a separate measurement of the intensity decay of the total emission. The expressions are suitable for any number of exponential components in both the intensity decay and the anisotropy decay. The formalism is generalized for global analysis of anisotropy decays measured at different excitation wavelengths and for different intensity decay times as the result of quenching. Additionally, we describe the expressions required for associated anisotropy decays, that is, anisotropy decays where each correlation time is associated with a decay time present in the anisotropy decay. And finally, we present expressions appropriate for distributions of correlation times. This article should serve as a reference for researchers using frequency-domain fluorometry. 相似文献
35.
Henryk Malak Ignacy Gryczynski Jonathan D. Dattelbaum Joseph R. Lakowicz 《Journal of fluorescence》1997,7(2):99-106
We observed the emission of l,6-diphenyl-l,3,5-hexatriene (DPH) when excited with the fundamental output of a fs Ti:sapphire
laser at 860 nm. The emission spectra of DPH were identical to that observed for one-photon excitation at 287 nm. The dependence
of the DPH emission intensity on laser power was cubic, indicating three-photon excitation of DPH at 860 nm. At a shorter
wavelength of 810 nm, the dependence on laser power was quadratic, indicating a two-photon process. At an intermediate wavelength
of 830 nm the mode of excitation was a mixture of two- and three-photon excitation. At 830 nm the anisotropy is no longer
a molecular parameter, and the mode of excitation and anisotropy of DPH depends on laser power. Frequency-domain anisotropy
decays of DPH in triacetin revealed the same rotational correlation times for two- and three-photon excitation. However, the
time 0 anisotropy of DPH was larger for three-photon excitation than for two-photon excitation. Steady-state anisotropy data
for DPH-labeled membranes revealed the same transition temperature for one- and three-photon excitation. These anisotropy
data indicate that membrane heating was not significant with three-photon excitation and that three-photon excitation may
thus be of practical usefulness in fluorescence spectroscopy and microscopy of membranes. 相似文献
36.
The crystal structure of HoPt2Si2 was determined using powder neutron diffraction data. It is tetragonal, CaBe2Ge2 type (space group P4/n mm). Neutron diffraction and magnetometric measurements indicate that HoPt2Si2 remains paramagnetic at the temperature of 2.0 K. 相似文献
37.
We measured the wavelength-dependent intensity decays of 4,9-dihydro-4,6-dimethyl-9-oxo-1H-imidazo-1,2a-purine (Yt-base) in propanol to determine the time-resolved emission spectra and rates of spectral relaxation. We found that resolution of the spectral relaxation times was dramatically improved by global analysis of the frequency-domain data with increasing amounts of the collisional quencher CCl4. Collisional quenching preferentially decreases the longer-lived relaxed component of the emission, thereby increasing the fractional contribution of the incompletely relaxed portion of the emission. The data could not be explained by a single spectral relaxation time, and at least two relaxation times are needed to describe the time-dependent emission center of gravity of Yt-base.Dedicated to Professor Stefan Paszyc on the occasion of his 70th birthday. 相似文献
38.
Zygmunt Eckstein Ewa Lipczyńska-Kochany Ewa Leszczyńska 《Monatshefte für Chemie / Chemical Monthly》1983,114(8-9):1009-1011
A series of new quinolinecarbohydroxamic acids has been prepared by treatment of corresponding methyl quinolinecarboxylates with hydroxylamine. 相似文献
39.
Joseph R. Lakowicz Bogumil Zelent Józef Kuśba Ignacy Gryczynski 《Journal of fluorescence》1996,6(4):187-194
Fluorescence quenching of Nile Blue by amines is thought to be due to electron transfer to the excited dye molecule from the amine electron donor. We used electron transfer quenching of Nile blue byN,N-diethylaniline in propylene glycol as a model system for an interaction which depends exponentially on distance. We investigated the time dependence of the presumed distance-dependent process using gigahertz harmonic-content frequency-domain fluorometry. The frequency-domain data and the steady-state quantum yield were analyzed globally based on either the Smoluchowski-Collins-Kimball radiation boundary condition (RBC) model or the distancedependent quenching (DDQ) model, in which the rate of quenching depends exponentially on the flourophore-quencher distance. We performed a global analysis which included both the frequencydomain time-resolved decays and the steady-state intensities. The latter were found to be particularly sensitive to the model and parameter values. The data cannot be satisfactorily analyzed using the RBC model for quenching. The analysis shows the excellent agreement of the DDQ model with the experimental data, supporting the applicability of the DDQ model to describe the quenching by the electron transfer process, which depends exponentially on the donor-acceptor distance. 相似文献
40.
Ewa Skrzypczak-Jankun Andrzej Hoser Elżbieta Grzesiak Zygmunt Kałuski Maria D. Rozwadowska 《Journal of chemical crystallography》1979,9(5):233-244
Both of the title compounds crystallize in the monoclinic system: C23H17NO2 (Ib),P21/c,a = 8.970(1),b = 22.629(5),c = 9.101(1) Å, = 106.08(1) °,Z = 4,D
x
= 1.27 Mg m–3; C19H17NO2 (Ic),P21/a,a = 15.225(2),b = 6.429(1),c = 17.190(1) Å, = 112.99(1) °,Z = 4,D
x
= 1.25 Mg m–3. The structures were solved and refined by standard methods, both toR 0.04. In compound Ib, a weak intramolecular interaction is observed between the nitrogen atom from the isoquinoline ring and the carbon atom from the carbonyl group, with the N(2) . C(18)distance being 2.98 Å. In compound Ic, the PhCO2 -fragment is twisted in the opposite direction to that in compound Ib, without hydrogen bonding. The pK
a
and IR data were considered in the light of the results of the X-ray investigation. 相似文献