Determination of intracellular pH using sensitive, clickable fluorescent probes

Area of Science:

• Chemical Biology
• Molecular Imaging
• Biochemistry

Background:

• Accurate measurement of intracellular pH is crucial for understanding cellular processes.
• Existing fluorescent pH probes often lack sensitivity, photostability, or optimal pKa for specific organelles.

Purpose of the Study:

• To synthesize and evaluate novel acidic fluorescent pH probes.
• To assess probe performance for intracellular pH monitoring, particularly in acidic organelles.

Main Methods:

• Synthesis of a series of acidic fluorescent pH probes.
• Titration analyses to determine pH dependence and fluorescence changes.
• Fluorescent imaging of HepG2 and Hela cells to evaluate intracellular pH sensing capabilities.

Main Results:

• Developed probes with high pH dependence, sensitivity, photostability, and cell permeability.
• Probe 3 exhibited an 800-fold fluorescence intensity increase between pH 8.0 and 4.1.
• Probe 3 demonstrated effective monitoring of intracellular hydrogen ion [H+] levels in cellular imaging.

Conclusions:

• The synthesized probes, particularly probe 3, are highly effective for intracellular pH sensing.
• The probes' optimal pKa facilitates the study of acidic organelles.
• Terminal alkyne/azido groups enable library expansion via click chemistry for diverse sensor development.