Naphthalimide-Based, Single-Chromophore, Emission Ratiometric Fluorescent Sensor for Tracking Intracellular pH.

Area of Science:

• Biochemistry
• Cell Biology
• Fluorescence Imaging

Background:

• Intracellular pH (pH_i) is a critical regulator of cellular processes.
• Accurate monitoring of pH_i is essential for understanding cell function and disease.
• Existing pH sensors have limitations in terms of sensitivity, cell permeability, or photostability.

Purpose of the Study:

• To develop and characterize a novel, cell-permeable pH sensor for live-cell imaging.
• To enable ratiometric quantification of intracellular pH in the acidic range (~pH 3-6).
• To demonstrate the sensor's utility in tracking dynamic changes in cellular pH.

Main Methods:

• Synthesis and characterization of the novel pH sensor, TRapH.
• In vitro assessment of TRapH's pH-sensitive ratiometric emission response.
• Live-cell imaging experiments in mammalian cells to monitor intracellular pH dynamics.
• Induction of pH changes using a synthetic proton (H⁺) transporter.

Main Results:

• TRapH exhibits a reversible, cell-permeable nature.
• The sensor displays a pH-sensitive ratiometric emission response in the acidic range (approximately pH 3-6).
• TRapH successfully enabled real-time imaging and quantification of intracellular pH in living mammalian cells.

Conclusions:

• TRapH is a promising tool for monitoring acidic intracellular pH environments.
• The sensor facilitates the live-tracking of dynamic pH changes in response to biological stimuli.
• TRapH opens new avenues for investigating pH-dependent cellular processes.