Theoretical and Experimental Analysis of Protoporphyrin IX Photodegradation Using Multi‐Wavelength Light Sources

Abstract

Photodynamic procedures have been used in many applications, ranging from cancer treatment to microorganism inactivation. Photodynamic reactions start with the activation of a photosensitizing molecule with light, leading to the production of cytotoxic molecules that promote cell death. However, establishing the correct light and photosensitizer dosimetry for a broadband light source remains challenging. In this study, we proposed a theoretical mathematical model for the photodegradation of protoporphyrin IX (PpIX), when irradiated by multi‐wavelength light sources. The theoretical model predicts the experimental photobleaching (temporal change in PpIX concentration) of PpIX for different light sources. We showed that photobleaching occurs independently of the light source wavelengths but instead depends only on the number of absorbed photons. The model presented here can be used as an important mathematical approach to better understand current photodynamic therapy protocols and help achieve optimization of the doses delivered.

Combined Effects of Focused Ultrasound and Photodynamic Treatment for Malignant Brain Tumors Using C6 Glioma Rat Model

“…Tumor death induced by PDT is considered to be due to the following: 1) direct killing, 2) destruction of neovascularization, or 3) inflammatory and immune response. 26 27 To confirm the therapeutic effect of PDT, Ki-67 expression and TUNEL assay, rather than factors corresponding to the apoptotic cascade, have often been used. 24 Since the core mechanism of these treatments is unclear, we analyzed the treatment efficacy by focusing on the expression level of ROS.…”