A pyrazolo[1,5-a]pyridine-based ratiometric fluorescent probe for sensing Cu²⁺ in cell

Area of Science:

• Chemical Sensing
• Fluorescent Probes
• Molecular Imaging

Background:

• Förster Resonance Energy Transfer (FRET) probes offer advantages like pseudo-Stokes shifts and environmental correction.
• Existing FRET systems often lack optimal donor-acceptor spectral overlap, necessitating new fluorophore development.
• Copper ions (Cu²⁺) play crucial roles in biological processes, making their detection important.

Purpose of the Study:

• To synthesize a new pyrazolo[1,5-a]pyridine derivative as a donor for a FRET-based ratiometric fluorescent probe.
• To develop a highly selective and sensitive sensor for Cu²⁺ detection.
• To demonstrate the probe's utility in biological samples, specifically glioma cells.

Main Methods:

• Synthesis of a novel pyrazolo[1,5-a]pyridine fluorescent dye.
• Construction of a ratiometric fluorescent probe utilizing Förster Resonance Energy Transfer (FRET) and Photoinduced Electron Transfer (PET) mechanisms.
• Characterization of the probe's selectivity and sensitivity towards Cu²⁺ using spectrofluorometry.
• Application of the probe for intracellular Cu²⁺ detection in Glioma cells.

Main Results:

• A new pyrazolo[1,5-a]pyridine dye was successfully synthesized and employed as a FRET donor.
• The developed ratiometric probe exhibited high selectivity and sensitivity for Cu²⁺ with a detection limit of 30 nM.
• The probe effectively detected endogenous Cu²⁺ levels within Glioma cells, demonstrating its biological applicability.

Conclusions:

• The novel pyrazolo[1,5-a]pyridine-based FRET probe provides a robust platform for ratiometric Cu²⁺ sensing.
• The probe's ability to function in biological environments highlights its potential for cellular imaging and diagnostics.
• This work addresses the need for improved fluorophores in FRET systems for sensing applications.