Evaluation of a custom-built time-resolved system for simultaneous detection of photosensitizer-mediated singlet oxygen (1O2) luminescence and fluorescence

This study developed and validated a combined system for simultaneous detection of photosensitizer-mediated singlet oxygen (1O2) luminescence and fluorescence. The system might provide a unique tool for studying 1O2 dosimetry. Superconducting strip photon detector (SSPD) and time-resolved system were used for detecting 1O2 luminescence of 1270 nm. Spectral analyzer and photodiode were used for detecting photosensitizer fluorescence. Rose Bengal (RB) was used as model photosensitizer and Q-switch laser of 532 nm as excitation light source. The combined system could simultaneously detect 1O2 luminescence and fluorescence. 1O2 lifetimes and specific fluorescence of RB dissolved in various solutions were obtained and analyzed. Results were consistent with published data. Linear relationship between RB concentration and 1O2 concentration as well as linear correlation between fluorescence intensity and RB concentration were demonstrated under RB concentration < 10 μM. The custom-built system can be used for simultaneous measurement of photosensitizer-mediated production of 1O2 and fluorescence.