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Abstract
The photophysical properties of the canonical DNA/RNA nucleobases can be modified by selective functionalization. The carbonyl functional group at the C6 position of guanine or 2-amino-6-oxopurine, for example, can be removed to form 2-aminopurine, thus replacing the ultrafast internal conversion pathway to the ground state observed in guanine with slow internal conversion and intersystem crossing pathways in 2-aminopurine.1 Similarly, substitution of the carbonyl oxygen in guanine with a heavier atom results in a redshift of the absorption spectrum and a remarkable modulation of the electronic relaxation pathways of the DNA nucleobase. More specifically, sulfur substitution redshifts the absorption spectrum of guanine and allows for efficient population of the reactive triplet state upon ultraviolet excitation.4 This reactive triplet state makes 6-thioguanine useful in photodynamic therapy applications, as it can participate in reactive oxygen species generation. Substitution of the carbonyl oxygen with an even heavier selenium atom further redshifts the absorption spectrum of guanine, while also increasing the molar absorptivity coefficients in the near visible wavelengths (350-400 nm).5 If the excited state properties of 6-selenoguanine are also conducive to reactive oxygen species generation then this DNA derivative could be used as a potentially superior topical photodynamic therapy agent. The rationale for this hypothesis is that a redshift in the absorption spectrum allows for deeper penetration of light into tissue during a photodynamic treatment.
Symposium Date
Fall 12-1-2012
Keywords
6-selenoguanine, transient absorption spectroscopy, photophysics
Disciplines
Chemistry
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Recommended Citation
Merrick, Collin; Hoehn, Sean J.; Ortiz-Rodríguez, Luis A.; Krul, Sarah; and Crespo-Hernández, Carlos E., "Remarkable Sensitivity of the Prospective Photodynamic Therapy Agent 6-Selenoguanine to pH" (2012). Intersections Fall 2020. 15.
https://commons.case.edu/intersections-fa20/15