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Updated: Apr 5, 2026

Single Molecule Analysis of Laser Localized Psoralen Adducts
Published on: April 20, 2017
DNA Intercalated Psoralen Undergoes Efficient Photoinduced Electron Transfer
Sascha Fröbel1, Anna Reiffers1, Christian Torres Ziegenbein1
1Institut für Physikalische Chemie, Heinrich Heine Universität, Gebäude 25.43.01, Universitätstrasse 1, 40225 Düsseldorf, Germany.
Abstract:
The interaction of psoralens with DNA has been used for therapeutic and research purposes for decades. Still the photoinduced behavior of psoralens in DNA has never been observed directly. Femtosecond transient absorption spectroscopy is used here to gain direct insight into the photophysics of a DNA-intercalated psoralen (4'-aminomethyl-4,5',8-trimethyl-psoralen (AMT)). Intercalation reduces the excited singlet lifetime of AMT to 4 ps compared with 1400 ps for AMT in water. This singlet quenching prohibits the population of the triplet state that is accessed in free AMT. Instead, a DNA to AMT electron transfer takes place. The resulting radical pair decays primarily via charge recombination with a time constant of 30 ps. The efficient electron transfer observed here reveals a completely new aspect of the psoralen-DNA interaction.
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