NIR-II AIEgens for Phototheranostics: Design, Applications and Perspectives

Area of Science:

• Materials Science
• Biomedical Engineering
• Chemistry

Background:

• Aggregation-induced emission (AIE) is a promising phenomenon for developing advanced imaging and therapeutic agents.
• The second near-infrared (NIR-II) window (1000-1700 nm) offers deeper tissue penetration and reduced background autofluorescence for biomedical applications.
• Integrated phototheranostics combining imaging and therapy can improve cancer treatment efficacy.

Purpose of the Study:

• To review rational molecular engineering strategies for designing AIE-active molecules emitting in the NIR-II window.
• To explore the application of these NIR-II AIEgens in multimodal imaging and synergistic cancer therapy.
• To discuss the potential of AIE-based platforms for precision cancer theranostics.

Main Methods:

• Systematic review of molecular engineering approaches (D-A, D-A-D, A-D-A systems) for NIR-II AIEgens.
• Analysis of AIEgen characteristics including absorption/emission, AIE properties, and decay pathways.
• Evaluation of nanoformulations for stability, biocompatibility, and targeting via the EPR effect.

Main Results:

• Engineered D-A, D-A-D, and A-D-A systems achieve red-shifted NIR-II absorption/emission and enhanced AIE properties.
• AIEgens enable high-contrast NIR-II fluorescence and photoacoustic imaging for precise tumor localization.
• These molecules facilitate efficient photothermal and photodynamic therapies through type-I and type-II mechanisms.

Conclusions:

• Nanoformulated NIR-II AIEgens offer excellent stability, biocompatibility, and passive tumor targeting.
• "All-in-one" AIE platforms demonstrate synergistic photothermal/photodynamic therapy under multimodal imaging guidance.
• AIE-based integrated phototheranostics represent a promising paradigm for precision cancer theranostics, with challenges in clinical translation and combination therapy noted.