A two-photon fluorescent probe for viscosity imaging in vivo

= 800 nm). Fluorescence lifetime imaging (FLIM) of living HeLa cells stained with MCN revealed that the intracellular average viscosity value was 73.45 ± 21.55 cP in cytosol. Imaging in living tissue slices indicated that MCN can work in deep tissue (∼130 μM) under two-photon excitation. Moreover, MCN also showed the capacity for in vivo imaging viscosity in zebrafish with obvious fluorescence emission.