Singlet Oxygen Luminescence Image in Blood Vessels During Vascular-Targeted Photodynamic Therapy

Singlet oxygen (¹ O₂ ) is widely regarded as the main cytotoxic substance that induces the biological damage for photodynamic therapy (PDT). In this study, the previously developed near-infrared (NIR) optical imaging system was optimized for fast imaging of ¹ O₂ luminescence. The optical imaging system enables direct imaging of ¹ O₂ luminescence in blood vessels within 2 s during vascular-targeted PDT (V-PDT), which makes this system extremely practical for in vivo studies. The dependence of RB concentration on ¹ O₂ luminescence image was investigated for V-PDT, and the data imply that 1270 nm signal is attributed to ¹ O₂ luminescence. The imaging system operates with a field of view of 9.60 × 7.68 mm² and a spatial resolution of 30 μm, which holds the potential to elucidate the correlation between cumulative ¹ O₂ luminescence and vasoconstriction for V-PDT.