Spherical mesoporous Fe-N-C single-atom nanozyme for photothermal and catalytic synergistic antibacterial therapy

Nanozyme has been regarded as an efficient antibiotic to kill bacteria using the reactive oxygen species (ROS) generated by Fenton-like reaction. However, its activity is still unsatisfied and requires large amount of hydrogen peroxide with side effects toward normal tissues. Herein, spherical mesoporous Fe-N-C single-atom nanozyme (SAzyme) is designed for antibacterial therapy via photothermal treatment enhanced Fenton-like catalysis process. Due to the large pore size (4.0 nm), high specific surface area (413.9 m² g^-1) and uniform diameter (100 nm), the catalytic performance of Fe-N-C SAzyme is greatly improved. The Michaelis-Menten constant (K_m) is 4.84 mmol L^-1, which is similar with that of horseradish peroxidase (3.7 mmol L^-1). Moreover, mesoporous Fe-N-C SAzyme shows high photothermal conversion efficiency (23.3 %) owing to the carbon framework. The catalytic activity can be enhanced under light irradiation due to the elevated reaction temperature. The bacteria can also be killed via physical heat effect. Due to the synergistic effect of nanozyme catalysis and photothermal treatment, the antibacterial performance is much higher than that using single antibacterial method. This work provides an alternative for combined antibacterial treatment via photothermal treatment assisted catalytic process using spherical mesoporous single-atom nanozyme as an antibiotic.