A Stable Open-Shell Conjugated Diradical Polymer with Ultra-High Photothermal Conversion Efficiency for NIR-II Photo-Immunotherapy of Metastatic Tumor

Highlights By employing side-chain regulation, the photothermal therapy response of conjugated diradical polymer can red-shift from near-infrared (NIR)-I to the NIR-II region. This strategy offers new radical materials in developing NIR-II photothermal materials. The conjugated diradical polymer TTB-2 receives a record-high photothermal conversion efficiency of 87.7%, far beyond the recently reported NIR-II photothermal agents. Such conjugated diradical polymer must enrich the NIR-II photothermal agents’ library and provide important insight for more diradical polymer construction. The conjugated diradical polymer nanoparticles TTB-2 NPs achieve good tumor photoablation with navigation of photoacoustic imaging in the NIR-II window, without any side effect. Furthermore, the efficient photo-immunity effect prevents the pulmonary metastasis of breast cancer.