The application of amide units in the construction of neutral functional dyes for mitochondrial staining

To develop a new class of neutral fluorescent dyes with mitochondrial staining capacity, a series of functional dyes were obtained from Nile Red (2a-e) and coumarin (3a-e) with different amide compounds via Suzuki coupling reactions. The Nile Red derivatives (2a-e) emitted red fluorescence (590-660 nm) and coumarin derivatives (3a-e) showed blue emission (455-490 nm) in organic solvents. In addition, they exhibited high fluorescence quantum yields (0.27-0.98) in organic solvents and excellent photostability (>92%). Moreover, all of them possessed low cytotoxicity. More importantly, Nile Red borate (2) and coumarin borate (3) only accumulated in lipid droplets, while after being modified by different amide compounds, dyes 2a-e and 3a-e could successfully target mitochondria in HeLa cancer cells via confocal fluorescence experiments. This work provides a new strategy for the design of neutral cellular probes for mitochondrial staining.

Automated summary

A new class of neutral fluorescent dyes with mitochondrial staining capacity was developed using a series of functional dyes obtained from Nile Red and coumarin via Suzuki coupling reactions. These dyes showed high fluorescence quantum yields and excellent photostability in organic solvents, and exhibited low cytotoxicity. Through confocal fluorescence experiments, it was demonstrated that modified dyes successfully targeted mitochondria in HeLa cancer cells.