Fe3O4–Au–polydopamine hybrid microcapsules with photothermal–photodynamic synergistic anti-bacterial performance

Infectious diseases associated with drug-resistant bacteria increasingly threaten public health. Effective antibacterial nanoplatforms are of special importance for treating bacterial infections. In this work, a novel magnetic Fe3O4–Au–PDA hybrid microcapsule with both photothermal (PTT) and photodynamic (PDT) anti-bacterial functions was developed. First, the Fe3O4@Au/PDA core/shell microspheres with hollow nature were obtained by a simple in situ redox–oxidize polymerization method. Then, they were etched in acid to improve the hollow interior and porous shell. Finally, the tetracarboxyzinc phthalocyanine (ZnPc) was used as the photosensitizer to be loaded into the above Fe3O4–Au–PDA hybrid microcapsule. Owing to the dual-mode photothermal Au–PDA hybrid shell and the ZnPc photosensitizer, the final Fe3O4–Au–PDA/ZnPc hybrid microcapsule serves as a wonderful photothermal/photodynamic (PTT/PDT) synergistic therapy agent. The experimental results show that the Fe3O4–Au–PDA/ZnPc microcapsule possesses excellent photothermal sterilization effect (808 nm laser irradiation) against Escherichia coli, and the experimental results further demonstrate good photodynamic behavior under Xenon lamp irradiation. The product exhibits much higher antibacterial performance by combining the PTT/PDT treatment, which demonstrates that this work provides a novel dual-mode phototheranostic nano-agent for an effective treatment of bacterial infections.