Monitoring of Time-Resolved Singlet Oxygen Luminescence at 1270nm by an Optical Fiber Detection System

Singlet oxygen (1O2) is the main cytotoxic substance in Type II photodynamic therapy (PDT). The luminescence of 1O2 at 1270[Formula: see text]nm is extremely weak with a low quantum yield, making the direct detection of 1O2 at 1270[Formula: see text]nm very challenging. In this study, a set of highly sensitive optical fiber detection system is built up to detect the luminescence of photosensitized 1O2. We use this system to test the luminescence characteristics of 1O2 in pig skin tissue ex vivo and mouse auricle skin in vivo. The experimental results show that the designed system can quantitatively detect photosensitized 1O2 luminescence. The 1O2 luminescence signal at 1270[Formula: see text]nm is successfully detected in pig skin ex vivo. Compared with RB in an aqueous solution, the lifetime of 1O2 increases to [Formula: see text]s in pig skin tissue ex vivo. Experiments on living mice suggest that an enhancement of 1O2 intensity with the increase of the TMPyP concentration. When the dose is 25[Formula: see text]mg/kg, the vasoconstriction can reach more than 80%. The results of this study hold the potential application for clinical PDT dose monitoring using an optical fiber detection system.