Reactive Oxygen Species Generation (upon Photoactivation)

Reactive oxygen species (ROS) generation upon photoactivation refers to the process by which certain molecules, known as photosensitizers, produce highly reactive oxygen-derived species when exposed to light in the presence of molecular oxygen. The excited triplet-state photosensitizer can transfer energy or electrons to molecular oxygen, leading primarily to two types of ROS generation mechanisms: Type I (electron transfer reactions to generate superoxide anion, hydrogen peroxide, and hydroxyl radicals) and Type II (energy transfer directly produces singlet oxygen). The ROS generated depend on the nature of the photosensitizer, local environment, and available substrates. This mechanism is central to photodynamic therapy (PDT), photocatalysis, and various biomedical and environmental applications. At controlled levels, ROS are used therapeutically for targeted cell killing; at excessive levels, they can cause oxidative damage.

Other names

Photoactivated ROS generationLight-induced ROS productionPhotosensitizationSinglet oxygen generationSuperoxide generationHydroxyl radical generation

Light-activated generation of reactive oxygen species (singlet oxygen, superoxide, hydroxyl radical) via Type I (electron transfer) or Type II (energy transfer) mechanisms involving a photosensitizer and molecular oxygen.