DNA photo-cleaving agents that localize in mitochondria are of significant research interest in photodynamic therapy due to their ability to selectively trigger apoptosis of irradiated cancer cells. Strong absorption of light in the 700 nm to 900 nm near-infrared photo-therapeutic window is also highly desirable. Biological chromophores take up light minimally in this wavelength region, leading to enhanced penetration of incident irradiation and facile activation of photosensitizing agents. In this study, we will present our recent data describing the DNA interactions of a near-infrared 4-quinolinium pentamethine carbocyanine dye that has been modified with two mitochondrial-targeting triphenyl phosphonium groups. UV-visible absorption spectra recorded in aqueous pH 7.0 buffer reveal pronounced interactions with calf thymus (CT) DNA and strong absorption of near-infrared light. Irradiation of micromolar concentrations of the dye at 830 nm generates direct breaks in plasmid DNA in high yield (pH 7.0, 10 degrees C). We will explore the possibility of using the triphenyl phosphonium modified 4-quinolinium carbocyanine to photosensitize oxidative damage to mitochondrial DNA in tissue culture cells.

DNA photocleavage mediated by a triphenyl phosphonium-modified carbocyaninedDye

ACS Spring Meeting 2021

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