Berlin 2014 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 11: Biomolecules 1

MO 11.7: Vortrag

Mittwoch, 19. März 2014, 15:30–15:45, BEBEL HS213

Ultrafast Spectroscopic Studies of Cyclic Tetrazolium Cell Dyes and their Photoproducts — •Florian Kanal, Domenik Schleier, Nina Schopf, and Patrick Nuernberger — Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg

Tetrazolium salts are cyclic dyes which are commonly used for testing cell viabilities by detecting formazans as their enzymatically metabolised ring-open forms. The influence of light is often ignored in these assays, although for some tetrazolium salts photochemical reduction to formazans has been reported.

The ultrafast photochemistry of two of the most prominent tetrazolium salts, 2,3,5-Triphenyl-tetrazolium chloride (TTC) and 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-tetrazolium bromide (MTT) was investigated in alcoholic and different pH-valued aqueous solutions by ultrafast spectroscopy. Both compounds yield the formazan via reaction channels involving different short-living ring-open and -closed structures within few nanoseconds either in alcoholic (TTC) or in basic (MTT) solution.

Depending on the solvent, TTC-formazan shows either the formation of a bicyclic radical or huge conformational changes in the formazan skeleton upon long-time irradiation. In contrast, the ultrafast dynamics of TTC- and MTT-formazan are almost unaltered if the solvent is changed. As only the primary steps of both reactions take place on an ultrafast time-scale, involvement of a long-living state is most likely for the final product formation.