Improving Quantum Yield of a NIR-II Dye by Phenylazo Group

Area of Science:

• Organic Chemistry
• Materials Science
• Biomedical Imaging

Background:

• Structure-fluorescence correlation is crucial for designing effective fluorescent probes.
• Donor-acceptor-donor (D-A-D) fluorophores offer tunable optical properties.
• Near-infrared-II (NIR-II) imaging requires probes with high quantum yield (QY) in biological environments.

Purpose of the Study:

• Synthesize and characterize novel D-A-D NIR-II fluorophores.
• Investigate the impact of donor moiety substituents on fluorescence properties.
• Develop a stable, high-QY NIR-II probe for in vivo biological applications.

Main Methods:

• Synthesis of D-A-D fluorophores with varying donor groups (amino, tert-butyloxycarbonyl amino, phenylazo).
• Theoretical and experimental investigation of electronic structures and optical properties.
• Encapsulation of the phenylazo-containing fluorophore in polystyrene-co-poly(ethylene glycol) micelles.
• In vitro and in vivo fluorescence imaging in mice.

Main Results:

• Phenylazo substitution significantly enhanced the quantum yield (QY) of the NIR-II fluorophore.
• Micelle encapsulation maintained high QY (≈3.51%) in aqueous media (1000-1500 nm).
• Achieved high-speed, high-quality in vivo imaging of mice, including cardiac cycle and heart rate determination.
• Demonstrated significant tumor accumulation after intravenous injection.

Conclusions:

• The phenylazo-substituted D-A-D fluorophore is a promising NIR-II probe for biological imaging.
• Micelle formulation enhances probe stability and performance in aqueous environments.
• The developed probe exhibits potential for ultrafast in vivo imaging and sensitive tumor detection.