Visualizing Nitric oxide in mitochondria and lysosomes of living cells with N-Nitrosation of BODIPY-based fluorescent probes.

Nitric oxide (NO), a ubiquitous gasotransmitter which plays critical roles in cardiovascular, nervous, and immune systems related diseases, is closely related in the physiological and pathological processes of mitochondria and lysosomes. Thus, monitoring NO in mitochondria or lysosomes is very meaningful for NO related chemical biology. Herein, we rationally designed four NO probes, BDP-NO, Mito-NO-T, Mito-NO and Lyso-NO, based on BODIPY dye substituted at meso position with 5-amino-2-methoxy-phenyl scaffold. These four probes all showed fast fluorescence off-on response toward NO with excellent selectivity and high sensitivity with the detection limit of BDP-NO to reach 5.7 nM. We introduced triphenylphosphonium and morpholine moieties onto BODIPY scaffold respectively to enable organelle-targetability. MTT and flow cytometry assay demonstrated that the probes exhibited low cytotoxicity, which was beneficial to the biological application in living cells. Confocal fluorescence microscopy experiments confirmed excellent mitochondria targeting for Mito-NO and lysosome-targeting with Lyso-NO for the detection of NO in living cells.