LAUSR

Six mitochondria/lysosomes self-targetable and viscosity-sensitive dyes (1a-f) were developed via simple structure modification on cyanine-derived dyes. They all showed remarkable OFF-ON fluorescent response to viscosity in near-infrared region (652-690 nm) and exhibited good linear relationship with solution viscosity. The transient absorption spectra were used to evaluate the excited-state lifetime of dye 1a in different viscosity environments. Furthermore, cellular imaging assays indicated that different derivatives (1a-f) with the same chromophore core exhibited different organelle-targeting abilities. Among them, dyes 1a-c could sense lysosomal viscosity fluctuations while dyes 1d-f could be applied in mitochondrial viscosity detections.