BODIPY 581/591 C11 (Lipid Peroxidation Sensor) is a fluorescent dye that localizes to membranes and is used to measure lipid peroxidation in live cells. It is a highly sensitive fluorescent probe that has a shift in fluorescent emission upon oxidation of the polyunsaturated butadienyl portion of its fatty acid analog in live cells. When this occurs, fluorescence emission peaks shift from red (~590 nm) to green (~510 nm). BODIPY 581/591 C11 (Lipid Peroxidation Sensor) measures lipid peroxidation through the ratiometric shift in fluorescence between reduced and oxidized states of the probe.

Lipid peroxidation is the free radical oxidative degradation of lipids from excessive reactive oxygen species production. Oxidative damage to lipids produces lipid peroxides that can cause damage to cell membranes, leading to changes downstream in signaling pathways, eventually leading to cell death. Lipid peroxidation can occur during apoptotic cell death but has been recognized as a defining characteristic of the non-apoptotic cell death pathway ferroptosis. Ferroptosis is defined by iron-dependent, lipid peroxidation. An increase in ferroptosis occurs during aging, and pathologies including cancer, atherosclerosis, neurodegeneration, and cardiovascular disease.