A highly specific and ultrasensitive near-infrared fluorescent probe for imaging basal hypochlorite in the mitochondria of living cells

The development of highly specific and ultrasensitive fluorescent probes for tracking basal mitochondrial hypochlorite is very important to unravel its diverse cellular functions in the mitochondria of living cells. In this paper, we have developed a water-soluble, mitochondria-targeted near-infrared fluorescent probe NB-OCl for selectively measuring OCl- in the presence of higher concentration (500 μM) other biologically important substances. Surprisingly, the obtained results demonstrated that probe NB-OCl could sensitively determine OCl- in the range of 0-200 pM with the detection limit of 10.8 pM. To the best of our knowledge, NB-OCl is the first fluorescent probe for the specific determination of OCl- at the picomolar level. Moreover, probe NB-OCl exhibits a fast response for OCl- (< 5 s), which would be in favor of tracking the highly reactive and short-lived OCl- in the living systems. The preeminent recognition properties of probe NB-OCl enable its applications in the monitoring of basal OCl- and the fluctuations of endogenous/exogenous OCl- levels in the mitochondria of living cells.