TADF Dye-Loaded Nanoparticles for Fluorescence Live-Cell Imaging.

Area of Science:

• Materials Science
• Chemistry
• Biotechnology

Background:

• Thermally activated delayed fluorescence (TADF) molecules are crucial for efficient organic light-emitting diodes, utilizing triplet states without heavy metals.
• TADF emitters exhibit a small singlet-triplet energy gap, enabling reverse intersystem crossing for delayed fluorescence.
• Current limitations for TADF in biological applications include poor biocompatibility, low aqueous solubility, and reduced performance in polar media.

Purpose of the Study:

• To develop a method for utilizing TADF emitters in biological imaging by overcoming their limitations in polar media.
• To create novel TADF-emitting nanomaterials suitable for live-cell imaging applications.
• To demonstrate the preservation of TADF photophysical properties in aqueous environments using polymeric nanoparticles.

Main Methods:

• Two established TADF emitters were loaded onto polystyrene nanoparticles via a swelling procedure.
• The resulting TADF-emitting nanomaterials were characterized using optical spectroscopy.
• The cytotoxicity and cellular uptake of the nanoparticles were evaluated in live human cancer cells.

Main Results:

• The synthesized nanoparticles exhibited characteristic TADF emission in aqueous media, with the polymeric matrix protecting the dyes from solvent effects.
• The TADF nanomaterials demonstrated very low cytotoxicity towards live human cancer cells.
• Effective cellular uptake allowed for fluorescence microscopy imaging at low concentrations.

Conclusions:

• Polymeric nanoparticles provide a versatile platform for adapting TADF emitters for biological applications, maintaining their photophysical properties.
• The developed TADF nanomaterials are suitable for live-cell imaging due to their biocompatibility, aqueous stability, and efficient cellular uptake.
• This facile method offers a generalized approach for creating TADF-based bio-imaging tools.