Highly Stable Near-Infrared\nII Luminescent Diradicaloids\nfor Cancer Phototheranostics

Near-infrared II (NIR-II) phototheranostic agents have\nbecome prominent\nagents for the early diagnosis and precise treatment of cancer. Organic\nopen-shell diradicaloids with distinct structure and narrow band gap\nare promising candidates for phototherapeutic agents due to their\nstrong spin-coupling effect and NIR light-harvesting capacity. However,\nachieving stable and efficient NIR-II luminescent diradicaloids is\ncrucial yet rather challenging considering their high chemical reactivity\nand self-absorption. Herein, two highly stable NIR-II luminescent\ndiradicaloids, 2PhNVDPP and PhNVDPP, were successfully fabricated\nby employing an acceptor planarization/π-conjugation extension\nand donor rotation strategy. After encapsulation into water-dispersible\nnanoparticles (NPs), 2PhNVDPP NPs exhibit NIR-II luminescence, high\nPCE of 53%, and improved photo/heat stability. <i>In vivo</i> experiments with 2PhNVDPP NPs demonstrated the clear visualization\nof blood vessels and tumors, as well as the successful NIR-II imaging-guided\nphotothermal ablation of tumors. This study not only develops a pioneering\nstable diradicaloid phototherapeutic agent with NIR-II luminescence\nbut also provides a unique perspective for the effectiveness of multimodal\nanticancer therapy.