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Optical Spectroscopy Study of the Interaction Between Quercetin and Human Serum Albumin

100%
Wybranowski T., Kruszewski S.
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vol. 125
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issue 4A
A-57-A-60
EN
Optical methods are very useful for the study on behavior of molecules in albumin-containing solutions. The interaction between quercetin (QUE) and human serum albumin (HSA) under physiological conditions was investigated by the methods of UV-Vis absorption and fluorescence spectroscopy. Fluorescence data show that enhancing of quercetin fluorescence in the presence of HSA is the result of formation of the HSA-QUE complex. On the basis of fluorescence data, the binding affinity constant of quercetin to HSA is determined. In this paper we have attempted to perform a kinetic study of the oxidation of quercetin in presence of human serum albumin by absorption spectroscopy. It has been shown that quercetin easily oxidizes at pH 7.4. The addition of HSA to quercetin solution induces changes in the absorption spectrum. In the human serum albumin solution, the time of quercetin oxidation is longer than in the case of quercetin diluted in phosphate buffered saline. Human albumin also contributes to stabilization of quercetin. These results suggest that HSA prevents degradation of quercetin in blood.
2
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Determination of the Protein-Binding Properties of Camptothecins by Means of Optical Spectroscopy Methods

81%
Ziomkowska B., Cyrankiewicz M., Wybranowski T., Kruszewski S.
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vol. 125
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issue 4A
A-61-A-65
EN
Optical spectroscopy methods are widely used in studies of drugs. The affinity of camptothecins - anticancer agents - to human serum albumin (HSA) was determined in this work. Camptothecins (CPTs) exist in two forms: active lactone and open ring inactive carboxylate. In blood, the hydrolysis process of lactone form occurs which leads to deactivation of CPTs. Research is being done on biophysical properties of synthesized CPT compounds, in particular on binding to albumin. The affinity to plasma proteins is an important determinant of stability of CPTs in blood. The following analogues of CPT were tested in this paper: irinotecan, SN-38, topotecan, and 9-amino camptothecin. Using the method of fluorescence anisotropy measurement, the association constants of the studied compounds to HSA were determined. The authors attempted to determine the deactivation rate of topotecan in HSA solution using Principal Component Analysis and Factor Analysis of absorption spectra recorded during hydrolysis process of lactone form.
3
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Silver Nanoparticles as Enhancing Substrates for Raman and Fluorescence Spectroscopy

81%
Cyrankiewicz M., Wybranowski T., Kruszewski S.
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vol. 125
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issue 4A
A-11-A-15
EN
The enhancing properties of silver nanoparticles in surface-enhanced Raman scattering (SERS) and metal-enhanced fluorescence (MEF) are studied in this work. The obtained results confirm that the partial aggregation of nanoparticles leads to a great increase of Raman scattering cross-section but there are significant differences in SERS-activity of colloidal silver treated with various aggregating compounds. The differences are interpreted through the analysis of both experimental and computational results. The same silver colloid covered with silica shell preventing the fluorescence quenching makes possible a several-fold increase in fluorescence emission. The effect strongly depends on thickness of the outer layer of nanoparticles. Geometrical parameters of nanoparticles (radius or radius and thickness of the adsorption layer in core-shell systems) are determined on the basis of the dynamic light scattering (DLS) data and extinction spectra analysis.
4
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Enhancement of FITC Fluorescence by Silver Colloids and Silver Island Films

71%
Kruszewski S., Wybranowski T., Cyrankiewicz M., Ziomkowska B., Pawlaczyk A.
Acta Physica Polonica A
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2008
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vol. 113
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issue 6
1599-1608
EN
Silver colloids and silver island films as fluorescence enhancement systems are the subject of this paper. Enhancement of fluorescence of molecules placed near metallic nanoparticles is a result of resonance interaction of exciting and emitted lights with surface plasmons. Two models explaining this phenomenon are presented. Processes of silver colloids and silver island films forming are described. Results of extinction, absorption and scattering studies of fluorescence enhancement systems are presented. The influence of these systems, i.e. silver colloids and silver island films on the fluorescence of fluorescein-5-isothiocyanate was studied. 7-fold increase in fluorescence intensity of fluorescein-5-isothiocyanate molecules placed near silver nanoparticles was observed.
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