Light‐Activated Pharmaceuticals: Mechanisms and Detection

Abstract

Photodynamic therapy relies on the interaction between light, oxygen and a photosensitizing agent. Its medical significance relates to the ability of certain agents, usually based on porphyrin or phthalocyanine structures, to localize somewhat selectively in neoplastic cells and their vasculature. Subsequent irradiation, preferably at a sufficiently high wavelength to have a significant pathway through tissues, results in a photophysical reaction whereby the excited state of the photosensitizing agent transfers energy to molecular oxygen and results in the formation of reactive oxygen species. Analogous reactive nitrogen species are also formed. These contain both nitrogen and oxygen atoms. The net result is both direct tumor cell death and a shutdown of the tumor vasculature. Other processes may also occur that promote the anti-tumor response but these are outside the scope of this review.

Analysis of the In Vivo and In Vitro Effects of Photodynamic Therapy on Breast Cancer by Using a Sensitizer, Sinoporphyrin Sodium

“…OH, . O 2 - , ONOO - , OCl - , and 1 O 2 17 , 18 , and it has been used as a common probe for intracellular ROS detection in PDT studies 19 , 20 , 21 . Briefly, cells were incubated with 10 μM DCHF-DA at 37°C for 30 min prior to PDT treatment.…”

Antitumor Effect of Sinoporphyrin Sodium‐Mediated Photodynamic Therapy on Human Esophageal Cancer Eca‐109 Cells

“…2,7‐DCF‐diacetate (DCFH‐DA), a nonfluorescent cell‐permeant compound, is hydrolyzed by endogenous esterases within the cell and the de‐esterified product can be converted into the fluorescent compound DCF upon oxidation by intracellular ROS. It has been reported the specificity of DCF is quite broad, with a spectrum that includes H 2 O 2 , ˙OH, , ONOO − , OCl − and 1 O 2 and it has been used as a common probe for intracellular ROS detection in PDT studies . To estimate the intracellular ROS, we added 10 μ m of DCFH‐DA before PDT treatment, and at 2 h posttreatment, we harvested the cells, detected and analyzed DCF fluorescence by flow cytometry .…”

Design, Synthesis, Selective Recognition Properties and Targeted Drug Delivery Application

“…The net result is both direct tumor cell death and a shutdown of the tumor vasculature. 57 When the cells to be killed are pathogenic microorganisms, the procedure is termed photodynamic inactivation (PDI), 58 lethal photosensitization 59 or photoactivated disinfection (PAD) in the dental field. 60 Porphyrins are an important group of PSs with high therapeutic potential showing considerable selectivity for cancer cells and light absorption in the long wavelength visible region.…”

“…[97][98][99] The employed molecular mechanisms have been intensively reviewed. 57,85,[100][101][102][103][104][105] The type of cell death triggered by PDT is dependent on the localization of the PS in cells, reflecting the chemical nature of the PS, as well as the applied incubation protocol. 106,107 The sub-cellular location governs much of the signaling that occurs after PDT.…”