A highly specific far-red fluorescent probe for imaging endogenous peroxynitrite in the mitochondria of living cells

The development of sensitive methods for imaging endogenous peroxynitrite (ONOO−) in the mitochondria of living cells is very important to disclose its diverse physiological and pathological functions. In this paper, we have described a simple, mitochondria-targeted far-red fluorescent probe Mito-PN for selectively detecting ONOO− even though in the presence of higher concentration (1 mM) other biologically important substances. The experimental results indicated that probe Mito-PN could quantitatively determine ONOO− in the range of 0.5–8 μM with the detection limit of 17 nM. In addition, probe Mito-PN exhibits a fast response for ONOO− (<5 s), which is favorable for monitoring the highly reactive and short-lived ONOO− in the biological systems. The excellent sensing properties of probe Mito-PN enable its applications in the tracking of the fluctuations of endogenous ONOO− levels in the mitochondria of living cells.