Dual mode monitoring probe for mitochondrial viscosity in single cell

Viscosity strongly influences intracellular transportation of mass and signal, and although bulk viscosity can be well measured with macroscopic samples quantities, microscale measurements in live cells still remain a challenge. By introducing a CHO group into the meso-position of the pentamethine chain, a thiazole-Cy5 dye based two-photon fluorescence probe, Mito-V, was developed. It exhibited a selective response to solution viscosity by fluorescence ratio and lifetime methods. More importantly, Mito-V can localize in mitochondria and quantitatively image its viscosity changes by the dual fluorescence mode during the apoptosis.