Mesoporous polydopamine coated bismuth sulfide nanocomposites with great photothermal conversion, antibacterial and antioxidant performances

The scarcity of alternative drugs to antibiotics has posed a serious threat of global antibiotic-resistant bacteria. Achieving a delicate balance between antibacterial activity and anti-inflammatory effects within infected tissues is essential for promoting efficient wound healing. Herein, a novel near-infrared (NIR)-responsive nanomaterial (BSMC NPs) is developed via the in-situ growth of mesoporous polydopamine (MPDA) on the surface of Bi ₂ S ₃ , followed by the incorporation of curcumin (Cur) into the mesopores and onto the surface through the π-π stacking interactions. This organic-inorganic hybrid system exhibits superior photothermal conversion efficiency alongside notable antioxidant capabilities. Upon exposure to NIR light, the photothermal effect facilitates the generation of reactive oxygen species (ROS) by both Bi ₂ S ₃ and MPDA, leading to effective bacterial eradication. Conversely, in the absence of light stimulation, the intrinsic antioxidant properties of MPDA and curcumin enable rapid scavenging of excessive ROS, thereby conferring anti-inflammatory benefits. The pH and NIR dual-responsive release behavior of curcumin has been experimentally validated. Antibacterial assays demonstrate that the BSMC nanoparticles achieve inhibition rates of 98.5% against Staphylococcus aureus ( S. aureus ) and 92.4% against Escherichia coli ( E. coli ) under 808 nm laser irradiation. The antibacterial mechanism involves increased permeability of bacterial membranes and leakage of bacterial contents, which is caused by localized hyperthermia and ROS generation. This work offers novel insights into the design of multifunctional biomaterials that integrate antioxidant, antibacterial, and photothermal therapeutic functionalities.