Polyethylenimine modified MoS₂ nanocomposite with high stability and enhanced photothermal antibacterial activity

The widespread bacterial infections accompanied by drug resistance, resulting from the abuse of traditional antibiotics, motivates researchers to develop effective antibacterial substitutes. Current researches have focused on positive antibacterial composites to promote interactions with bacteria, however facing challenges of unstable binding and low antibacterial efficiency. Here, we used covalent bonds to construct polyethylenimine modified Molybdenum disulfide (MoS₂-PEI) nanocomposite to achieve tight combination and improve stability. We employed bifunctional groups including thiol and carboxylate group as a linker to firmly connect MoS₂ and PEI. The covalent bonding strategy not only enhanced the stability of MoS₂-PEI but also promoted the binding of MoS₂-PEI to the surface of bacteria through electrostatic interaction. The distribution of MoS₂-PEI around bacteria studies proved that positively charged MoS₂-PEI could efficiently bind with negative bacteria. These two binding modes achieved accumulation of MoS₂-PEI around bacteria and shortened the distance of reactive oxygen species (ROS) destruction. Moreover, the photothermal property of MoS₂-PEI generated deep-penetrating heat and accelerated the oxidative stress. Under NIR light irradiation, MoS₂-PEI exhibited synergistically prominent antibacterial efficacy against both Escherichia coli and Staphylococcus aureus and displayed long term bactericidal effect after 1 week storage. This work could contribute as an alternative to improve the effectiveness of current disinfection treatments.