Covalent organic framework with second near-infrared aggregation-induced emission for boosted tumor multimodal phototheranostics.

Abstract

Covalent organic frameworks (COFs) are promising materials for cancer phototherapy, however, achieving precise multimodal theranostics in deep tissues remains challenging due to their typically short emission wavelengths. To address this limitation, we developed for the first time a COF with second near-infrared aggregation-induced emission (NIR-II AIE) characteristics, termed COF-AIE, by noncovalently incorporating the NIR-II AIE-active molecule BTT-COOH into TB-COF. COF-AIE exhibits an emission peak at ∼1000 nm, demonstrating exceptional NIR-II AIE properties. Importantly, the confinement of BTT-COOH within the COF framework affords the enhanced NIR-II fluorescence intensity compared to free BTT-COOH. Beyond that, COF-AIE retains the excellent photothermal conversion efficiency of BTT-COOH, while its high porosity promotes oxygen diffusion, boosting reactive oxygen species generation. These synergistic enhancements were further corroborated by density functional theory calculations. By integrating multiple optimized properties, COF-AIE achieves outstanding performance in NIR-II fluorescence imaging-navigated photothermal-photodynamic synergistic therapy towards tumor.