A ratiometric fluorogenic nanoprobe for real-time quantitative monitoring of lysosomal pH
Xin Zhang, Anna du Rietz, Jiwen Hu, Caroline Brommesson, Xiongyu Wu, Kajsa Uvdal, Zhangjun Hu
Abstract
Lysosomes are known as key players in cellular signalling and act as terminal degradation stations involved in a multitude of cellular processes. Being a highly influential physiological factor, pH is essential in the regulation of lysosome-mediated physiological and pathological processes. Aberrant pH fluctuations are highly related to lysosomal dysfunction that correlates to lysosomal storage diseases and neurodegenerative disorders. As such, real-time quantitative monitoring of lysosomal pH (pHL) is crucial for gaining insight into lysosomal dysfunction but challenging by the lack of effective lysosome-specific probes with high signal fidelity. Toward this end, we have proposed a lysosomal fluorogenic nanoprobe (TR-MP) for reliable ratiometric measuring of pHL. It is fabricated by rational manipulation of fluorescence resonance energy transfer (FRET) in a tailorable nanoplatform. The nanoprobe consists of biocompatible silica nanoparticles assembled with a pH-sensitive rhodamine derivative (RDM-TEOS) as an acceptor and aggregation-induced emission (AIE) fluorophore (TPE-OMe) as a donor to ensure high energy transfer efficiency. Further equipped with cell-penetrating facilitator and morpholine to enable effective cell-internalization and high lysosome affinity of TR-MP. Results show that TR-MP can quantitatively measure pH in a range of 3.0 – 7.0 and detect pHL fluctuations in live cells under various stimuli, as well as real-time monitor pHL during apoptosis.