Precise phase adjustment and antibacterial property of copper sulfide particles in confined mesoporous silica nanoreactor

Bacteria-caused wound infection greatly threatens human health, thus developing an efficient and safe antibacterial agent without drug resistance is still a great challenge. Herein, a confined vulcanization strategy is proposed to construct copper sulfides-loaded dual-mesoporous silica nanospheres (CuxSy@DMSNs) with various crystal phases for reactive oxygen species (ROS)-mediated and photothermal antibacterial application. With the pore confinement of DMSNs, the crystal phases of copper sulfides including CuS, Cu9S5 and Cu1.96S can be easily controlled by changing the vulcanization temperature. The relationships between the crystal phases and photothermal properties as well as peroxidase-like activity of copper sulfides were systematically investigated. Results show that the obtained CuS@DMSNs exhibited higher photothermal ability with remarkable photothermal conversion efficiency of 36.86% in the second near-infrared region (NIR-II) and better peroxidase-like activity, compared to those of Cu9S5@DMSNs and Cu1.96S@DMSNs. As a result, the in vitro experiments showed the good antibacterial effect against both gram-negative E. coli and gram-positive S. aureus under 1064 nm laser irradiation and the presence of H2O2. Besides, the CCK-8 assay indicated that CuS@p-DMSNs have minimal cytotoxicity against normal human umbilical vein endothelial cells at the ranged concentrations. Therefore, the resultant CuS@p-DMSNs could act as a promising antibacterial agent for deep wound bacterial infection treatment.