Rational Design of an Amphiphilic Membrane-Anchored Fluorescent Probe for Weakly Alkaline pH Bioimaging

Area of Science:

• Cell Biology
• Biochemistry
• Chemical Biology

Background:

• Intracellular membrane structures create unique microenvironments crucial for organelle function and signaling.
• Weakly alkaline pH microdomains are vital but challenging to study due to a lack of suitable fluorescent probes.

Purpose of the Study:

• To engineer a novel membrane-anchored fluorescent probe, CAlkM, for sensitive and selective imaging of weakly alkaline intracellular pH.
• To demonstrate the probe's utility in live cells and organisms for visualizing pH-related biological processes.

Main Methods:

• Rational design and synthesis of the coumarin-based fluorescent probe CAlkM.
• Characterization of CAlkM's pKa and pH-dependent fluorescence response.
• Application of CAlkM in live-cell imaging using STED microscopy and in zebrafish larvae.

Main Results:

• CAlkM exhibits a pKa of 8.24 and sensitive fluorescence across the pH 7.0-9.0 range.
• The probe selectively detects weakly alkaline conditions and localizes to membrane-associated regions in cells.
• CAlkM enables high-resolution in situ visualization of pH changes and demonstrates pH-responsive imaging in zebrafish.

Conclusions:

• CAlkM is a versatile membrane-anchored fluorescent probe for imaging weakly alkaline intracellular environments.
• The study establishes a molecular design strategy for developing advanced pH-sensing probes.
• CAlkM provides a valuable tool for investigating pH-regulated physiological and pathological processes in complex biological systems.