Theoretical study on the multi-mechanism synergistic bactericidal effect of asymmetric Janus AuNPs–PS microspheres

With the overuse of antibiotics and the emergence of increasingly complex application scenarios, single-strategy bactericidal approaches are proving increasingly inadequate in today's environment. How to simultaneously attack multiple "targets" from multiple dimensions has become one of the hot topics in current research. This study proposes a multi-mechanism synergistic antibacterial platform based on Janus polystyrene-gold nanoparticle (AuNPs-PS) microspheres using COMSOL 6.3. This platform achieves the displacement motion of Janus AuNPs-PS microspheres through the UV-induced photothermal effect (PTT), and combines dielectrophoretic force (DEP) to enable controlled enrichment and directional arrangement of the microspheres. It achieves enhanced sterilization efficiency through the synergistic interaction of the photothermal effect and DEP based on Janus AuNPs. The study first simulated the light absorption-scattering model of AuNPs-PS microspheres under UV irradiation, verifying that the microspheres can generate a temperature field <i>via</i> the photothermal effect. Subsequently, the motion of the microspheres under thermophoresis and their effective separation under DEP were simulated to assess their feasibility in practical applications. Finally, the paper compares the bactericidal rates achieved by the microspheres under UV irradiation alone <i>versus</i> under multi-mechanism synergy. Simulation results indicate that the synergistic effect of multiple mechanisms yields a bactericidal efficacy approximately 30% higher than that of a single strategy. Among these, UV itself has a bactericidal effect. Relevant literature indicates that AuNPs can generate high temperatures under the photothermal effect, thereby disrupting bacterial membrane structures to a certain extent. Furthermore, the photocatalytic effect on the AuNP surface can catalyze the production of large amounts of reactive oxygen species (ROS) under appropriate conditions, facilitating the inactivation of certain bacteria. The PS matrix serves as an ideal carrier for AuNPs, with its excellent functionalization and dielectric properties providing the foundation for DEP manipulation. Furthermore, the spatial targeting and enrichment effect of DEP significantly enhances the local microsphere concentration and contact efficiency with bacteria. This multi-synergistic approach combining "physical enrichment-photothermal-photocatalysis" offers a potential strategy for overcoming bacterial resistance barriers. Under simulated conditions, it demonstrates promising removal potential against persistent biofilms, providing a theoretical mechanism for combating drug-resistant bacterial infections without readily inducing resistance. However, this inference requires validation through biological experiments. The study aims to provide theoretical foundations and simulation guidance for developing highly efficient sterilization technologies.