A Simple Fluorescent Probe for Sensing pH and its Application in E. coli Cells.

Abstract

We designed and synthesized a simple fluorescent probe, (E)-2-(2-(3,4,5-Trimethoxybenzylidene)hydrazinyl) benzothiazole (probe), which could be applied to the detection of strongly acidic and alkaline pH in DMSO/water (1/4, v/v) system. It could be used to quantitatively detect strong acid in the range of 2.60-3.53 with a pKa of 2.78. Meanwhile, it also showed an excellent linear relationship between the fluorescence intensity and alkaline pH values over the range of 9.98-10.95 with a pKa of 9.32. The probe exhibited excellent properties to pH with high selectivity and sensitivity. The mechanism studies showed that the H+ binding with the N atom of benzothiazole moiety and hydrazine moiety in acid solution while the deprotonation of N atom in hydrazine group in basic environment. Importantly, the probe was successfully applied for imaging the strongly acidic and alkaline in E.coil cells.