Structural Effect On The Cellular Selectivity Of An Nir-Emitting Cyanine Probe: From Lysosome To Simultaneous Nucleus And Mitochondria Selectivity With Potential For Monitoring Mitochondria Dysfunction In Cells

Bright red to NIR emitting cyanine probes 2-3 were synthesized in very good yields. Probes 2-3 exhibited excellent fluorescent quantum yields (phi(fl) approximate to 0.1-0.4) and large Stokes shift (Delta lambda > 150 nm) due to efficient intramolecular charge transfer (ICT) in the conjugated pi system. Organelle specificity of these probes was investigated by live cell fluorescence confocal microscopy studies. Probe 3 exhibited the ability to visualize the cell nucleus and mitochondria simultaneously in live cell samples during imaging experiments. However, in structurally modified probe 2 with different substituents (i.e., benzothiazolium vs benzothiazole), the selectivity of the probe switched entirely toward cellular lysosomes. Spectrometric DNA titration experiments were conducted to confirm the DNA/nucleus selectivity of probe 3. The study further evaluates the role of the substituent toward DNA selectivity. Probe 3 was identified as a valuable fluorescent marker to visually identify and study mitochondrial dysfunction in live cells via fluorescent confocal microscopy.