Quantifying the photochemical damage potential of fluorescence contrast agents: singlet oxygen production

Recent advances in optical imaging have the potential to significantly improve patient outcomes. Among the most promising approaches under development is contrast-enhanced fluorescence imaging, which can be performed with molecular targeting to enhance tumor visualization. One key issue that has not been rigorously addressed is the potential phototoxicity of these fluorophores. In this study, we have used a commercial cell-free assay to qualify the singlet oxygen production rate in approved (ICG, Methylene Blue) and unapproved (IRDye700, IRDye800) fluorophores. Results shed light on the relative phototoxicity of each agent and will help to establish standardized methods for photochemical safety testing.