A supramolecular diazapyrene radical assembly with NIR absorption for selective photothermal antibacterial activity

A supramolecular radical assembly that can be induced <i>in situ</i> by facultative anaerobic bacteria has been reported and used for selective near-infrared (NIR) photothermal antibacterial action. Herein, we report the synthesis of a water-soluble diazapyrene derivative (DAPNP), which could be <i>in situ</i> initiated into the corresponding radicals by facultative anaerobic bacteria, such as <i>E. coli</i> or <i>S. aureus</i>. The introduction of cucurbit[10]uril (CB[10]) alters the stacking mode of the diazapyrene radical cations, resulting in a redshift of their characteristic absorption peak from the visible region to the NIR region. Under 660 nm laser irradiation, the <i>in situ</i>-induced supramolecular radical assembly exhibits great photothermal conversion properties and achieves highly efficient antibacterial activity (up to 98%). In contrast, with the aerobic <i>B. subtilis</i> it is difficult to induce the formation of diazapyrene radical cations <i>in situ</i> and maintain good activity under light irradiation. In addition, DAPNP@CB[10] exhibits excellent biocompatibility and has great potential as an intelligent photothermal material for antibacterial applications.