Introducing Rigidity into the GFP Chromophore via a Boron Bridge: Insights and Application in Two-Photon Imaging

Area of Science:

• Organic Chemistry
• Photophysics
• Biomedical Sensing

Background:

• Green fluorescent protein (GFP) is a widely used biological marker.
• Developing synthetic fluorophores with similar or improved properties is of significant interest.
• Controlling molecular conformation is key to achieving desired photophysical properties.

Purpose of the Study:

• To design and synthesize a new class of azaborine fluorophores.
• To mimic the chromophore of green fluorescent protein (GFP).
• To investigate their photophysical properties and potential for sensing applications.

Main Methods:

• Synthesis of ten novel azaborine compounds.
• Characterization of photophysical properties including fluorescence Stokes shifts and brightness.
• Development of zinc sensors using the synthesized fluorophores.
• Application of two-photon microscopy for biological sensing.

Main Results:

• A new family of ten azaborine fluorophores was successfully developed.
• These compounds mimic the GFP chromophore, with conformation locked by a hydroxyboron bridge.
• The fluorophores exhibit large Stokes shifts (up to 100 nm) and high brightness (>10^4 M^-1 cm^-1) in the 408-525 nm range.
• Zinc sensors were constructed, detecting 100 micromolar Zn2+ concentrations in biological systems using two-photon microscopy.

Conclusions:

• The developed azaborine fluorophores offer a promising alternative to traditional fluorescent probes.
• Their tunable properties and high brightness make them suitable for advanced imaging and sensing.
• Demonstrated utility in detecting biologically relevant metal ions highlights their potential in biomedical research.