Diffusion of Multiple Species Resolved by Fluorescence Lifetime Recovery after Photobleaching (FLRAP).

Fluorescence recovery after photobleaching (FRAP) is now an indispensable tool to analyze the diffusion of molecules in vivo and in vitro. However, a conventional fluorescence intensity-based approach has difficulty in analyzing the diffusion of multiple species simultaneously. Here, we report fluorescence lifetime recovery after photobleaching (FLRAP) that incorporates fluorescence lifetime information into FRAP. By using FLRAP, the fluorescence intensity-recovery curves of each species can be successfully extracted from the ensemble photon data by utilizing their species-specific fluorescence decay curves, which are verified by applying FLRAP to two heterogeneous systems. Thus, FLRAP can be a powerful tool to quantitatively elucidate the molecular diffusion of multiple species in complex systems such as in living cells.