Water-soluble fluorescent probes for bisulfite and viscosity imaging in living cells: Pyrene vs. anthracene.

Abstract

We have designed two mitochondria targetable probes P-Py and P-An by the π-conjugation of polyaromatic hydrocarbons (pyrene vs. anthracene) with 4-dimethylamino pyridinium. They present an amphiphilic property with excellent solubility in the common polar and non-polar solvents. Both of them demonstrated a significant fluorescence response to bisulfite in Tris-HCl buffer solutions (5\xa0mM, pH\xa0=\xa07.4). By a combination of fluorescence, UV-vis, time-resolved emission, 1H NMR, and ESI-MS, their sensing mechanisms have been elaborated to be a Michael addition. Notably, P-Py also exhibits a sensitivity to the viscosity change with a Stokes shift of 140\xa0nm, due to the restriction of C-C bond rotation. By taking advantages of its good water solubility, low toxicity, and high mitochondrial target, the dual responses of P-Py to exogenous SO2 derivatives and viscosity change in mitochondria were explored by confocal fluorescence microscopy.