Dicyanoisophorone derivatives with self-targeting abilities towards multiple organelles for fluorescent markers and viscosity detection

Abstract

To improve self-targeting abilities towards organelles, four fluorescent dyes (1a-1d) were designed by connection of dicyanoisophorone to phenylpiperidinol (1a), naphthalenol (1b), indazole (1c) and pyrene (1d) unit with a double bond. Their absorption maxima were located at 423–517 nm; and emission maxima were at 565–682 nm with large Stokes shifts of 142–191 nm. Moreover, their fluorescence intensities increased 11–117 fold in glycerol compared to phosphate buffer solution, which might be due to the long excited state lifetimes (up to 1 ns) by transient absorption spectra. Furthermore, laser confocal experiments with HeLa cells proved that dyes 1a-1d were self-target fluorescent markers at 10–20 μM for lysosomes, endoplasmic reticulum, mitochondria and lipid droplets respectively; and they could be used for the fluorescent probes at 2 μM for viscosity detection within corresponding organelles by influence of ionophores. In addition, these dyes were able to detect viscosity changes in a Parkinson's disease model with PC-12 cells.