On the Diffusion of Hypericin in Dimethylsulfoxide/Water Mixtures—The Effect of Aggregation
| Autor: | Jana Staničová, Alena Strejčková, Daniel Jancura, Jozef Uličný, Mikuláš Bánó, Jozef Marek, Pavol Miškovský, Gregor Bánó |
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| Rok vydání: | 2011 |
| Předmět: |
Anthracenes
Models Molecular Photosensitizing Agents Aqueous solution Chemistry Diffusion Molecular Conformation Water Fluorescence Fluorescence spectroscopy Absorption Surfaces Coatings and Films Hypericin chemistry.chemical_compound Spectrometry Fluorescence Monomer Tetramer Materials Chemistry Organic chemistry Dimethyl Sulfoxide Physical and Theoretical Chemistry Perylene Water content Nuclear chemistry |
| Zdroj: | The Journal of Physical Chemistry B. 115:2417-2423 |
| ISSN: | 1520-5207 1520-6106 |
| DOI: | 10.1021/jp109661c |
| Popis: | Hypericin (Hyp) is a natural photosensitizing pigment with a possible application in the photodynamic therapy of cancer. Hyp is readily dissolved in dimethylsulfoxide (DMSO) but forms nonsoluble aggregates in an aqueous environment. Fluorescence spectroscopy and diffusion coefficient measurements are used to investigate the self-association of Hyp molecules in DMSO/water mixtures. Fluorescence measurements reveal that Hyp remains in its monomeric form in DMSO/water mixtures containing up to ∼20-30 wt % water. At higher water concentration, Hyp starts to form nonfluorescent aggregates. To determine the size of the aggregates, the diffusion coefficient of Hyp is determined for different DMSO/water mixtures both experimentally and theoretically. Our data indicate that the size of the aggregates increases as more water is added into DMSO. At 50 wt % water content, the effective diffusion coefficient is about 30% smaller than the calculated value for the stacked Hyp tetramer. The results indicate that in an aqueous environment, Hyp presumably produces large molecular weight stacked H-aggregates. We have also confirmed that in an aqueous environment at alkaline pH, molecules of Hyp remain in the monomeric state. |
| Databáze: | OpenAIRE |
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