Thermoluminescence can be used to study lipid peroxidation in photosynthetic organisms.

Abstract

Oxidants attack lipids with carbon-carbon double bonds, causing the formation of lipid peroxyl radicals and hydroperoxides through a process called lipid peroxidation. Different aldehydes, including malondialdehyde, can also be formed as secondary products. The thiobarbituric acid reactive substances (TBARS) test is commonly used as an assay to measure lipid peroxidation, and its determination is based on spectrophotometric quantification of malondialdehyde. However, the TBARS test is not entirely specific for lipid peroxidation analysis because of the presence of other malondialdehyde sources and the possibility of reaction with other oxidation products. High temperature thermoluminescence technique is a useful method for studying lipid peroxidation in photosynthetic organisms. This technique measures the luminescence emission generated at high temperatures by some of the final products of lipid peroxidation. The breakdown of lipid peroxides is caused by high temperatures, which leads to the formation of carbonyl species in an excited triplet state. When chlorophyll molecules receive energy from excited carbonyls, they release this energy as luminescence once they settle into their ground state. Multiple studies have observed significant thermoluminescence emission bands at high temperatures caused by the energy transfer of lipid peroxidation by-products to chlorophyll. The band peaking at 115-130 °C correlates well with the concentration of different lipid peroxidation products. This band is an extremely sensitive in vivo indicator of the effects of stress conditions in photosynthetic materials. This technique has several benefits when used for lipid peroxidation assays. It is non-invasive, does not require the addition of external probes, and offers sensitive and continuous monitoring of peroxide levels.