Push-pull dioxaborine as fluorescent molecular rotor: far-red fluorogenic probe for ligand-receptor interactions.

Area of Science:

• Organic chemistry
• Photochemistry
• Biophysical chemistry

Background:

• Fluorescent probes are crucial for background-free detection of biomolecules.
• Solvatochromic dyes and molecular rotors are popular fluorogenic probes.
• There is a need for probes with enhanced spectroscopic properties and photostability.

Purpose of the Study:

• To introduce a novel push-pull boron-containing (dioxaborine) dye.
• To investigate its unique spectroscopic behavior combining solvatochromism and molecular rotor properties.
• To evaluate its potential for bioimaging applications.

Main Methods:

• Synthesis of a push-pull dioxaborine dye.
• Spectroscopic characterization in various organic solvents.
• Investigation of solvatochromism and molecular rotor properties (Förster-Hoffmann equation).
• Grafting of a reactive carboxy derivative to carbetocin.
• Cell-surface receptor imaging of the oxytocin receptor.

Main Results:

• The dioxaborine dye exhibits strong solvatochromism and viscosity-dependent fluorescence quantum yield.
• It possesses an exceptional extinction coefficient (120,000 M⁻¹ cm⁻¹), high quantum yields, and red/far-red emission.
• The dye demonstrates superior photostability compared to Nile Red in apolar media.
• The carbetocin conjugate shows a >1000-fold fluorescence turn-on in water and targets the oxytocin receptor with high signal-to-background ratio (>130).

Conclusions:

• The novel push-pull dioxaborine dye offers unique advantages for bioimaging.
• Its combined solvatochromic and molecular rotor properties, along with excellent photophysical characteristics, make it a promising fluorogenic probe.
• The successful application in targeting and imaging the oxytocin receptor highlights its potential for advanced cellular and molecular imaging.