Singlet oxygen (1O2)

Singlet oxygen is a highly reactive, electronically excited state of molecular oxygen that serves as a critical mediator in both pathological oxidative stress and targeted clinical interventions [1][4]. In the context of photodynamic therapy (PDT), it is the primary cytotoxic agent generated when a photosensitizer drug is excited by light and transfers energy to ground-state triplet oxygen [2]. This localized production allows for the precise destruction of malignant tumors and neovascularization in diseases like age-related macular degeneration [2][3]. Conversely, as a reactive oxygen species (ROS), singlet oxygen can cause significant damage to cellular membranes, proteins, and DNA, contributing to skin photoaging and inflammatory conditions [3][4]. Therapeutic management involves either the controlled induction of singlet oxygen for tissue ablation or the administration of antioxidants like carotenoids and tocopherols that act as quenchers to mitigate oxidative damage [1][4]. Its short half-life and high reactivity necessitate specialized detection methods, such as measuring its characteristic 1270 nm phosphorescence or monitoring downstream biomarkers of lipid peroxidation [1].

Other names

Singlet molecular oxygen1Δg oxygenExcited state oxygenReactive oxygen species

Generation of cytotoxic reactive species via Type II photosensitization for targeted tissue destruction, or neutralization through physical and chemical quenching by antioxidant molecules [1][2].