Near-infrared fluorescence imaging using organic dye nanoparticles

Area of Science:

• Biomedical Imaging
• Nanotechnology
• Organic Chemistry

Background:

• Near-infrared (NIR) fluorescence imaging (700-1000 nm) is crucial for early cancer detection.
• Conventional NIR dyes face limitations: low brightness, poor stability, and small Stokes shifts.

Purpose of the Study:

• To develop novel NIR probes with enhanced performance for in vitro and in vivo imaging.
• To overcome limitations of conventional NIR dyes using small-molecule organic dye nanoparticles (ONPs).

Main Methods:

• Encapsulation of NIR dyes within host ONPs to enable fluorescence resonance energy transfer (FRET).
• Host ONPs act as carriers, stabilizers, and light-harvesting agents.
• Surface modification for water dispersity and pH stability (pH 2-10 for 60 days).

Main Results:

• Organic dye nanoparticles exhibit ~50-fold increased brightness compared to pure NIR dyes.
• Achieved large Stokes shifts (~250 nm) and dramatically enhanced photostability.
• Demonstrated water-dispersity, size, and fluorescence stability over a wide pH range.
• Successful folic-acid aided specific targeting in vivo and ex vivo cellular imaging.
• Negligible toxicity observed during in vivo imaging.

Conclusions:

• Developed NIR-emissive organic nanoparticles offer a promising platform for advanced fluorescence imaging.
• These nanoparticles overcome key limitations of conventional NIR dyes, enhancing brightness and stability.
• Demonstrated potential for highly efficient and safe in vitro and in vivo bioimaging applications.