Evidence for singlet oxygen production from indocyanine green by electron paramagnetic resonance

Abstract

Indocyanine green (ICG) is a well-known dye used for cardiovascular fluorescence imaging in medicine and a potential photosensitizer for photodynamic therapy. Using electron paramagnetic resonance (EPR), we have shown that illumination of aqueous solutions of ICG leads to the generation of singlet oxygen. The use of a selective spin trap allowed for the rate of singlet oxygen generation to be determined which provides evidence that ICG undergoes Type II photosensitization.