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Updated: Dec 10, 2025
Visualizing Mitophagy with Fluorescent Dyes for Mitochondria and Lysosome
Published on: November 30, 2022
A red-emission fluorescent probe for visual monitoring of lysosomal pH changes during mitophagy and cell apoptosis
Xiaodong Wang1, Li Fan, Xiaoran Zhang
1Institute of Environmental Science, Shanxi University, Taiyuan, 030006, P. R. China. dc@sxu.edu.cn fanli128@sxu.edu.cn.
Abstract:
We presented a novel red-emission fluorescent probe (MSO) for selectively monitoring lysosomal pH fluctuation in living cells. The probe was designed by employing rhodamine B as the off-on pH sensitive moiety owing to the unique spirocycle group and morpholine as the lysosome targetable unit. Based on the H+-induced spirocyclic ring opening process, MSO displayed significant pH sensing properties around 590 nm, with a pKa value of 5.42 and a good linear pH response ranging from 5.00 to 6.00. Besides, the probe possessed other prominent photophysical properties such as good selectivity and excellent photostability as well as low cytotoxicity, together making the red-emission probe more favorable for long-time and real-time imaging in live cells. Furthermore, MSO selectively accumulated into lysosomes and successfully visualized the mitophagy, cell apoptosis and heat shock processes by monitoring the rise of lysosomal pH.
Insights
We developed a novel red-emission fluorescent probe (MSO) for tracking lysosomal pH changes in live cells. This probe enables real-time imaging of cellular processes like mitophagy and apoptosis.
Area of Science:
- Biochemistry
- Cell Biology
- Chemical Biology
Background:
- Lysosomal pH is crucial for cellular functions.
- Monitoring lysosomal pH dynamics is essential for understanding cell signaling and disease.
- Existing probes often lack selectivity or photostability for real-time imaging.
Purpose of the Study:
- To develop a novel red-emission fluorescent probe for selective monitoring of lysosomal pH fluctuations in living cells.
- To characterize the photophysical properties and cellular performance of the new probe.
- To demonstrate the probe's utility in visualizing key cellular events.
Main Methods:
- Design and synthesis of a rhodamine B-based fluorescent probe (MSO) incorporating a morpholine unit for lysosomal targeting.
- Characterization of the probe's pH-sensing mechanism, pKa value, and photophysical properties (emission wavelength, selectivity, photostability).
- Evaluation of probe's performance in living cells, including lysosomal accumulation, cytotoxicity, and visualization of mitophagy, apoptosis, and heat shock.
Main Results:
- The MSO probe exhibits red-emission with significant pH sensing around 590 nm, featuring a pKa of 5.42 and a linear response from pH 5.00 to 6.00.
- MSO demonstrates excellent photostability, selectivity, and low cytotoxicity, making it suitable for long-term live-cell imaging.
- The probe selectively targets lysosomes and successfully visualizes dynamic changes in lysosomal pH during mitophagy, apoptosis, and heat shock.
Conclusions:
- MSO is a novel, highly effective red-emission fluorescent probe for real-time lysosomal pH monitoring in living cells.
- Its favorable photophysical properties and lysosomal targeting capability make it a valuable tool for studying cellular processes.
- MSO provides new insights into lysosomal pH dynamics during various physiological and pathological conditions.
