Recyclable and well-dispersed Fe3O4@SiO2@polydopamine@Ag nanocomposite with enhanced photothermal effect for synergistic antibacteria effect

Bacterial infections represent one of the foremost threats to global human health. Furthermore, the misuse of antibiotics has exacerbated the public health crisis. Therefore, the development of high-performance novel antibacterial materials is of utmost importance. However, there are still several issues regarding the antibacterial performance and recyclability of existing antibacterial materials. To address these issues, this study synthesized a core@shell@shell@satellite structured Fe 3 O 4 @SiO 2 @polydopamine (PDA)@tannic acid (TA)@Ag nanocomposite, aiming to achieve excellent photothermal effect and synergistic antibacterial activity with silver. The composite particles exhibited improved dispersibility due to the SiO 2 coating. The modification of TA on the Fe 3 O 4 @SiO 2 @PDA achieved the uniform loading of silver nanoparticles (NPs), which significantly enhanced the photothermal conversion efficiency (η) of up to 74.9 %. Additionally, the superparamagnetic property facilitated magnetic separation, ensuring the efficient recovery and reutilization of the nanocomposites. Under low concentration and low-power near-infrared (NIR) light irradiation (808 nm, 1.0 W cm −2 ), the nanocomposite demonstrated excellent synergistic antibacterial activity, achieving efficient eradication of Escherichia coli (100 %) and Staphylococcus aureus (98 %). Furthermore, the material could be recycled up to five times without significant loss of antibacterial activity. Overall, our approach demonstrates the potential of novel multifunctional composite NPs in the treatment of bacterial infections and the sustainable application of antibacterial agents.