Exploration and application of a highly sensitive bis(salamo)-based fluorescent sensor for B4O72− in water-containing systems and living cells

Abstract

A highly selective fluorescent sensor H4L based on a bis(salamo)-type compound with two N2O2 chelating moieties as ionophore was successfully developed. Sensor H4L was found to have excellent selectivity for B4O72− over many other anions (Br−, CI−, CN−, CO32−, HCO3−, H2PO4−, HSO4−, NO3−, OAc−, S2O3−, SCN−, SO42−, Hcy (homocysteine) and H2O2), and it exhibited an approximately 150-fold enhancement of the fluorescence response to B4O72− in Tris-HCl buffer (DMF/H2O = 9:1, v/v, pH = 7) solutions. Significantly, its fluorescence intensity was enhanced in a linear fashion with increasing concentrations of B4O72−. The detection limit of sensor H4L towards B4O72− was 8.61 × 10−7 M. The test strips could conveniently, efficiently and simply detect B4O72− ions in Tris-HCl buffer (DMF/H2O = 9:1, v/v, pH = 7) solutions. Furthermore, sensor H4L showed excellent membrane permeability in living cells, and it was successfully used to monitor intracellular B4O72− by confocal luminescence imaging.