Evaluation of superconducting strip single photon detector-based system for singlet oxygen luminescence detection

<strong>Background:</strong> Singlet oxygen (¹O₂) is a key therapeutic molecule in photodynamic therapy (PDT). Quantitation of ¹O₂ luminescence is important for monitoring and optimizing PDT process. <strong>Objective: </strong>The aim of this study was to evaluate a custom-built superconducting strip single photon detector (SSPD)-based time-resolved photon counting system for ¹O₂ luminescence detection. <strong>Materials and Methods: </strong>The wavelength responses of optical collection system were verified by a spectrum analyzer. A dual-channel signal generator simulates pulsed signals of different frequencies were used to verify the circuit system. ¹O₂ luminescence generated by the photoexcitation of Rose Bengal solution was examined. Results: The ¹O₂ detection system could transmit photons of 1270 nm and the time-resolved system showed the response down to the nanosecond range and was capable of converting the different time responses into a square wave signal. When 10 μM aqueous and methanolic RB solutions were excited with a 20 mW 532 nm laser the measured ¹O₂ lifetimes were 2.93±0.37 μs and 9.45&plusmn;0.83 μs, respectively. At the same concentration, when the excitation power increased the number of singlet oxygen produced per unit of time also increased. <strong>Conclusions: </strong>The custom-built SSPD-based ¹O₂ detection system provides a reliable and sensitive means for the quantitation of ¹O₂ luminescence generated from PDT process.