High-Resolution Measurement of NADH and FAD Fluorescence Decay with the DCS-120 MP

The bh DCS-120 MP system is able to record single decay functions at extremely high precision and time resolution. We used the system to record decay functions of NADH and FAD with an IRF width of 19 ps. Fluorescence decay functions were obtained for NADH and FAD in aqueous solution, and in a diluted solution of citric acid at pH = 4. The decay curves are multi-exponential, with decay components as fast as 115 ps for NADH and 59 ps for FAD. The curves measured at pH = 7 and pH = 4 are significantly different, and they are different from decay curves recorded in cells. The procedures described can be used to supplement FLIM experiments with precision decay parameters of the fluorophores involved. Similar measurement can be performed with other bh FLIM systems, especially if these are equipped with bh’s ultra-fast HPM-100-06 detectors.