A New Rhodamine B‐based Fluorescent Probe for pH Detection and Bioimaging under Strong Acidic Conditions

Abstract

A new pH-sensitive rhodamine derivative was designed and synthesized using coupling reaction of rhodamine hydrazine with commercially available 3-bromo-4-hydroxybenzaldehyde, and characterized via NMR, HRMS, UV and fluorescent spectra. The obtained probe was marked with yellow fluorescence under neutral condition and pink in strongly acidic media. It has high quantum yields, is not susceptible to metal interference, and has high penetration ability for cell membrane and also further applicable in bioimaging.

A Colorimetric and Fluorescent pH Probe for Extremely Acidic Conditions and its Application in pH Test Paper

“…As a result, a number of fluorescent pH probes have been reported in the literature, functioning mainly at three pH regions: (1) cytosolic pH at 6.8–7.4, (2) lysosomal and endosomal pH at 4.5–6.0, and (3) mitochondrial pH at ~8.0 . However, fluorescent pH probes operating in extremely acidic conditions (pH < 4.0) are still rare . Although the most living species could not survive in extremely acidic conditions, there are still some microbes which prefer an extreme environment, e.g.…”