pH-sensitive fluorescent sensors based on europium(III) complexes.

Area of Science:

• Coordination Chemistry
• Materials Science
• Analytical Chemistry

Background:

• Development of sensitive fluorescent probes is crucial for monitoring pH in various environments.
• Europium(III) complexes offer unique luminescent properties for sensing applications.

Purpose of the Study:

• To design and synthesize novel europium(III) complexes as fluorescent pH probes.
• To evaluate the pH sensing capabilities of these complexes in aqueous solutions and biological systems.

Main Methods:

• Synthesis of europium(III) complexes: Eu(TTA)2-DSQ and Eu(TTA)3-DR1.
• Characterization of luminescent properties and pH sensitivity using luminescence titrations.
• Assessment of probe performance in cultured cells and in vivo.

Main Results:

• Eu(TTA)2-DSQ demonstrated high sensitivity for pH monitoring in neutral aqueous solutions with low background fluorescence.
• Eu(TTA)3-DR1, containing Rhodamine 6G and a Eu(III) moiety, exhibited pH sensitivity at pKa values of 5.0 and 7.2.
• Eu(TTA)3-DR1 successfully detected pH in both cultured cells and in vivo across acidic and near-neutral ranges.

Conclusions:

• The synthesized europium(III) complexes serve as effective fluorescent pH probes.
• These probes show promise for real-time pH monitoring in complex biological and chemical systems.
• The distinct pKa values and isolated protonation steps enable versatile pH detection.