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Feasibility of Using Fluoresceinyl Cypridina Luciferin Analog in a Novel Chemiluminescence Method for Real-time Photodynamic Therapy Dosimetry


*To whom correspondence should be addressed: Institute of Laser Life Science, South China Normal University, Guangzhou, 510631, PR China. Fax: 86-20-85216052; e-mail:


Singlet oxygen (1O2) is the most important cytotoxic agent in photodynamic therapy (PDT). The feasibility of using a chemiluminescence (CL) probe, 3,7-dihydro-6-[4-(2-(N′-(5-fluoresceinyl)thioureido)ethoxy)phenyl]-2-methylimidazo{1,2-a}-pyrazin-3-one sodium salt (fluoresceinyl Cypridina luciferin analog, FCLA), to monitor 1O2 production during PDT is evaluated in vitro. Lymphoma cells were treated with various protocols of PDT. The results show that the FCLA-CL production during PDT is linearly related to the corresponding cytotoxicity, regardless of the treatment protocol. With minimum cytotoxicity and interference to the PDT treatment outcome, the FCLA-CL system is an effective means to quantify PDT 1O2 production and may provide an alternative real-time dosimeter.