The Reactive Oxygen Species Singlet Oxygen, Hydroxy Radicals, and the Superoxide Radical Anion—Examples of Their Roles in Biology and Medicine

Abstract

Reactive oxygen species comprise oxygen-based free radicals and non-radical species such as peroxynitrite and electronically excited (singlet) oxygen. These reactive species often have short lifetimes, and much of our understanding of their formation and reactivity in biological and especially medical environments has come from complimentary fast reaction methods involving pulsed lasers and high-energy radiation techniques. These and related methods, such as EPR, are discussed with particular reference to singlet oxygen, hydroxy radicals, the superoxide radical anion, and their roles in medical aspects, such as cancer, vision and skin disorders, and especially pro- and anti-oxidative processes.

Controlled growth of ZnO nanoparticles using ethanolic root extract of Japanese knotweed: photocatalytic and antimicrobial properties

“…Finally, D 2 O was used to determine the role of singlet oxygen ( 1 O 2 ) in degradation. Since the lifetime of 1 O 2 is 55 μs in D 2 O and 3.3 μs in H 2 O, 44 singlet oxygen-mediated reactions should be accelerated in D 2 O compared to H 2 O, due to the longer lifetime of 1 O 2 and hence the higher number of active species. In our case, the degradation was only slightly faster compared to H 2 O, indicating that 1 O 2 does not contribute significantly to the overall degradation mechanism.…”

Nanotechnological approaches to address photosensitizers’ limitations: towards improved clinical applicability of photodynamic therapy

“…Enhanced therapeutic effect and eight-fold increase of accumulation compared to passive targeting were hence achieved in tumoral tissues of CT26 mice. [32] In the case of PSs that produce 1 O 2 and ROS with very short lifetimes, [33] it is particularly important for their efficacy to favor their cellular uptake through active targeting. Studies on active targeting revealed that the simple conjugation of moieties such as antibodies, [34] antibody fragments, [35] proteins, [36] and peptides [37] with molecular PSs can enrich their properties.…”

High Singlet Oxygen Generating Benzothienyl‐[b]‐fused BODIPY Nanoaggregates and Photoinduced Apoptosis in Human Carcinoma

“…[3,4] Among the others, 1 O 2 is a highly reactive, short-lived species and causes oxidation of organic matters. [5,6] PDT involving 1 O 2 species is considered to be localized as it has limited diffusion length. [7,8] To enhance the 1 O 2 generation, heavy non-metals (e. g., sulphur, bromine, iodine) or metals (Pt, Ir, etc.)…”