Cellular biomolecules as substrates for singlet oxygen

Cellular biomolecules as substrates for singlet oxygen refers to the broad range of organic molecules within a cell—primarily lipids, proteins, and nucleic acids—that undergo chemical oxidation upon reaction with singlet oxygen (1O2). Singlet oxygen is a highly reactive electronic state of molecular oxygen and is the primary cytotoxic mediator in photodynamic therapy (PDT). When a photosensitizing drug is activated by specific wavelengths of light, it generates 1O2, which subsequently attacks unsaturated fatty acids in membranes, specific amino acid residues (such as histidine, tryptophan, and methionine) in proteins, and guanine bases in DNA. These reactions lead to lipid peroxidation, protein cross-linking, and genomic damage, ultimately triggering cell death via apoptosis or necrosis. Because 1O2 has a very short half-life and a limited diffusion radius, the damage is highly localized to the site of photosensitizer accumulation. While this mechanism is effectively harnessed to treat localized cancers and dermatological conditions, the non-specific nature of the chemical attack means that any biomolecule in the vicinity of the activated drug can be a substrate, necessitating precise light delivery to avoid collateral damage to healthy tissue.

Other names

Singlet oxygen substratesTargets of photodynamic therapyCellular targets of 1O2Oxidizable cellular components

Photosensitizers absorb light energy to produce singlet oxygen, which then chemically reacts with and destroys nearby cellular biomolecules via oxidation, leading to cell death.