Unlocking the NIR-II AIEgen for High Brightness through Intramolecular Electrostatic Locking

Area of Science:

• Biomedical Engineering
• Materials Science
• Chemical Biology

Background:

• Near-infrared-II (NIR-II) window imaging offers non-invasive, radiation-free diagnostics.
• Developing bright NIR-II fluorophores remains a significant challenge for clinical applications.

Purpose of the Study:

• To enhance the brightness of NIR-II aggregation-induced emission (AIE) fluorophores.
• To explore intramolecular electrostatic locking as a strategy for AIE fluorophore brightness enhancement.
• To evaluate the potential of these enhanced fluorophores in in vivo imaging and biosensing.

Main Methods:

• Synthesized a novel TSEH molecule by introducing sulfur atoms into the thiophene bridge side chains.
• Investigated intramolecular interactions to lock the conjugated backbone's molecular motion.
• Encapsulated TSEH molecules into nanoparticles (NPs) and polystyrene nanospheres for application testing.

Main Results:

• TSEH molecules exhibited enhanced NIR-II fluorescent emission in both solution and aggregated states.
• TSEH NPs demonstrated a 2.6-fold increase in brightness compared to controls.
• In vivo studies showed feasibility for vascular and tumor imaging with high signal-to-background ratio.
• Lateral flow assays using TSEH-encapsulated nanospheres showed a 1.9-fold higher signal-to-noise ratio for antigen detection.

Conclusions:

• Intramolecular electrostatic locking is an effective strategy for developing bright NIR-II AIE fluorophores.
• The developed TSEH fluorophores show significant potential for advanced clinical diagnosis and biomedical research.
• This work paves the way for novel NIR-II imaging agents and diagnostic tools.