Monitoring Photoproduct Formation and Photobleaching by Fluorescence Spectroscopy Has the Potential to Improve PDT Dosimetry with a Verteporfin-like Photosensitizer¶

NIR-II Ratiometric Chemiluminescent/Fluorescent Reporters for Real-Time Monitoring and Evaluating Cancer Photodynamic Therapy Efficacy

The development of probes for early monitoring tumor therapy response may greatly benefit the promotion of photodynamic therapy (PDT) efficacy. Singlet oxygen (¹ O₂ ) generation is a typical indicator for evaluating PDT efficacy in cancer. However, most existing probes cannot quantitatively detect ¹ O₂ in vivo due to the high reactivity and transient state, and thus have a poor correlation with PDT response. Herein, a ¹ O₂ -responsive theranostic platform comprising thiophene-based small molecule (2SeFT-PEG) and photosensitizer Chlorin e6 (Ce6) micelles for real-time monitoring PDT efficacy is developed. After laser irradiation, the Ce6-produced ¹ O₂ could simultaneously kill cancer and trigger 2SeFT-PEG to produce increased chemiluminescence (CL) and decreased fluorescence (FL) signals variation at 1050 nm in the second near-infrared (NIR-II, 950-1700 nm) window. Significantly, the ratiometric NIR-II CL/FL imaging at 1050 nm could effectively quantify and monitor the concentration of ¹ O₂ and O₂ consumption or recovery, so as to evaluate the therapeutic efficacy of PDT in vivo. Hence, this ¹ O₂ activated NIR-II CL/FL probe provides an efficient ratiometric optical imaging platform for real-time evaluating PDT effect and precisely guiding the PDT process in vivo.

Photoproducts of the Photodynamic Therapy Agent Verteporfin Identified via Laser Interfaced Mass Spectrometry

Verteporfin, a free base benzoporphyrin derivative monoacid ring A, is a photosensitizing drug for photodynamic therapy (PDT) used in the treatment of the wet form of macular degeneration and activated by red light of 689 nm. Here, we present the first direct study of its photofragmentation channels in the gas phase, conducted using a laser interfaced mass spectrometer across a broad photoexcitation range from 250 to 790 nm. The photofragmentation channels are compared with the collision-induced dissociation (CID) products revealing similar dissociation pathways characterized by the loss of the carboxyl and ester groups. Complementary solution-phase photolysis experiments indicate that photobleaching occurs in verteporfin in acetonitrile; a notable conclusion, as photoinduced activity in Verteporfin was not thought to occur in homogenous solvent conditions. These results provide unique new information on the thermal break-down products and photoproducts of this light-triggered drug.