One probe for multiple targets: A NIR fluorescent rhodamine-based probe for ONOO− and lysosomal pH detection in live cells

Abstract

• A new rhodamine-based probe ONOO-LysopH was developed. • ONOO-LysopH responds to multiple targets: ONOO − and acidic pH. • ONOO-LysopH shows NIR fluorescence changes with a large Stokes shift. • ONOO-LysopH has a pKa of 5.41 and good lysosome-targeting ability. • ONOO-LysopH is applicable for cell imaging ONOO − and tracking lysosomal pH changes. Peroxynitrite and lysosomes are important biologically reactive oxygen species and subcellular organelles, respectively. The level of peroxynitrite and the value change of pH in lysosomes have a significant impact on living cells. Thus, the detection of peroxynitrite and lysosomal pH in live cells is very important. Herein, a novel probe ( ONOO-LysopH ) was developed, which not only can detect peroxynitrite in lysosomes, but also can be used to track the lysosomal pH changes. ONOO-LysopH is based on a new rhodamine derivate with near-infrared (NIR) emission and large Stokes shift. ONOO-LysopH is sensitive to acid and shows an instantaneous and reversible response of NIR emission around 686 nm with a pKa value of 5.41. ONOO-LysopH also exhibits a quick, sensitive, and selective response to peroxynitrite at physiological pH with a largely enhanced NIR fluorescence signal at 678 nm. The application of ONOO-LysopH to track lysosomal pH changes and image both endogenous and exogenous peroxynitrite in live cells was demonstrated. Thus, this work provided a potential multifunctional probe for peroxynitrite detection and lysosomal pH change tracking in live systems.