Localization of tumor by chemiluminescence probe during photosensitization action

Carbon dot-assisted luminescence of singlet oxygen: the generation dynamics but not the cumulative amount of singlet oxygen is responsible for the photodynamic therapy efficacy

A novel carbon dot-based luminescence probe for singlet oxygen (¹O₂) with a conventional optical detector has been implemented through the specific formation of electronically excited carbonyls from the breakdown of unstable endoperoxide intermediates, and its application in the real-time in vivo monitoring of ¹O₂ in photodynamic therapy (PDT) is achieved. More attractively, the relationship between the dynamics details of photosensitizer-generated ¹O₂ and the PDT efficacy has been established through a modified multiple-target survival model, enabling a direct and easy estimate of the surviving fraction of tumor cells from the generation dynamics of ¹O₂. Both in vitro and in vivo therapy results revealed that the rapid generation dynamics of ¹O₂ rather than its cumulative amount is responsible for better treatment efficacy in PDT. Overall, the deeper insight into the important roles of the generation dynamics of ¹O₂ in the PDT efficacy is irreplaceably advantageous in substantially reduced risks from deleterious treatment-related side effects by screening advanced photosensitizers and determining the light exposure end point.

Feasibility of using fluoresceinyl Cypridina luciferin analog in a novel chemiluminescence method for real-time photodynamic therapy dosimetry

Singlet oxygen ((1)O(2)) 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 (1)O(2) 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 (1)O(2) production and may provide an alternative real-time dosimeter.

Cyclodextrin-bound 6-(4-methoxyphenyl)imidazo[1,2-alpha+/-]pyrazin-3(7H)-ones with fluorescein as green chemiluminescent probes for superoxide anions

In providing chemiluminescent probes that have high chemiluminescence intensity and high specificity to superoxide anions, novel chemiluminescent probes involving cyclodextrins covalently bound to 6-(4-methoxyphenyl)imidazo[1,2-alpha]pyrazin-3(7H)-one with fluorescein were synthesized and characterized. Using the hypoxanthine-xanthine oxidase system for the generation of the superoxide anions, these novel chemiluminescent probes showed higher superoxide-induced chemiluminescence intensity than that of 6-[4-[2-[N(')-(5-fluoresceinyl)thioureido]-ethoxy]phenyl]-2-methylimidazo[1,2-alpha]pyrazin-3(7H)-one (FCLA). When tested at a probe concentration of 1.0 microM, compound 6, in which 6-(4-methoxyphenyl)imidazo[1,2-alpha]pyrazin-3(7H)-one and fluorescein are covalently attached on the secondary and primary hydroxyl faces of gamma-cyclodextrin, respectively, showed green luminescence intensity that was 26 times that of FCLA, which was also the highest luminescence intensity in this present study. At probe concentrations of less than 1.0 microM, the ratio of the superoxide-dependent chemiluminescence intensity to the background chemiluminescence intensity for compound 6 was higher than that of FCLA. This high superoxide-induced chemiluminescence intensity and superoxide specificity in low probe concentrations indicates that 6 can be more effective than FCLA toward the measurement of superoxide anions.