Mitochondria-Targeting Multifunctional Fluorescent Probe toward Polarity, Viscosity, and ONOO- and Cell Imaging

Abnormal changes occurring in the mitochondrial microenvironmentare important markers indicating mitochondrial and cell dysfunction.Herein, we designed and synthesized a multifunctional fluorescentprobe DPB that responds to polarity, viscosity, and peroxynitrite(ONOO-). DPB is composed of an electrondonor (diethylamine group) and electron acceptor (coumarin, pyridinecations, and phenylboronic acid esters), in which the pyridine groupwith a positive charge is responsible for targeting to mitochondria.D-& pi;-A structure with strong intramolecularcharge transfer (ICT) and twisted intramolecular charge transfer (TICT)properties give rise to respond to polarity and viscosity. The introductionof cyanogroup and phenylboronic acid esters increases the electrophilicityof the probe, which is prone to oxidation triggered by ONOO-. The integrated architecture satisfies the multiple response requirements.As the polarity increases, the fluorescence intensity of probe DPB at 470 nm is quenched by 97%. At 658 nm, the fluorescenceintensity of DPB increases with viscosity and decreaseswith the concentration of ONOO-. Furthermore, theprobe is not only successfully used to monitor mitochondrial polarity,viscosity, and endogenous/exogenous ONOO- levelfluctuations but also to distinguish cancer cells from normal cellsby multiple parameters. Therefore, as-prepared probe provides a reliabletool for better understanding of the mitochondrial microenvironmentand also a potential approach for the diagnosis of disease.