Variation of 1-pyrenebutyric acid fluorescence lifetime in single living cells treated with molecules increasing or decreasing reactive oxygen species levels

1-Pyrenebutyric acid (PBA) is a fluorescent probe whose fluorescence lifetime depends on local oxygen and free radical concentrations. We propose to use PBA fluorescence lifetime to quantify reactive oxygen species (ROS) in biological samples. Time-resolved microfluorimetry was used to record the fluorescence decay of single living cells loaded with this probe. We measured intracellular PBA fluorescence lifetimes and reduced nicotinamide adenine dinucleotide phosphate intensities under various oxygen concentrations. To confirm the feasibility of the new method, CCRF-CEM cells were treated with drugs that are known to increase or decrease ROS production. After treatment with adriamycin, we observed a decrease of PBA fluorescence lifetime. This corresponded to an increase of ROS concentration (80%). After treatment with cysteamine, we observed a reduction of the ROS concentration by 67%. Moreover, addition of exogenous H2O2 solution resulted in a decrease of PBA fluorescence lifetime due to a raising of the intracellular ROS concentration. These results support our hypothesis linking a part of PBA fluorescence lifetime variations to intracellular fluctuation of ROS.