A Supramolecular Radical Dimer: High-Efficiency NIR-II Photothermal Conversion and Therapy

Photothermal therapy at the NIR-II biowindow (1000-1350 nm) is drawing increasing interest because of its large penetration depth and maximum permissible exposure. Now, the supramolecular radical dimer, fabricated by N,N '-dimethylated dipyridinium thiazolo[5,4-d]thiazole radical cation (MPT.+) and cucurbit[8]uril (CB[8]), achieves strong absorption at NIR-II biowindow. The supramolecular radical dimer (2MPT(.+)-CB[8]) showed highly efficient photothermal conversion and improved stability, thus contributing to the strong inhibition on HegG2 cancer cell under 1064 nm irradiation even penetrating through chicken breast tissue. This work provides a novel approach to construct NIR-II chromophore by tailor-made assembly of organic radicals. It is anticipated that this study provides a new strategy to achieve NIR-II photothermal therapy and holds promises in luminescence materials, optoelectronic materials, and also biosensing.