Magnetic-Field-Induced Improvement of Photothermal Sterilization Performance by Fe[sub.3]O[sub.4]@SiO[sub.2]@Au/PDA Nanochains

Due to the abuse of antibiotics, the sensitivity of patients to antibiotics is gradually reduced. This work develops a Fe[sub.3]O[sub.4]@SiO[sub.2]@Au/PDA nanochain which shows an interesting magnetic-field-induced improvement of its photothermal antibacterial property. First, SiO[sub.2] was wrapped on Fe[sub.3]O[sub.4] nanospheres assembled in a chain to form a Fe[sub.3]O[sub.4]@SiO[sub.2] nanocomposite with a chain-like nanostructure. Then, the magnetic Fe[sub.3]O[sub.4]@SiO[sub.2]@Au/PDA nanochains were prepared using in situ redox-oxidization polymerization. Under the irradiation of an 808 nm NIR laser, the temperature rise of the Fe[sub.3]O[sub.4]@SiO[sub.2]@Au/PDA nanochain dispersion was obvious, indicating that they possessed a good photothermal effect. Originating from the Fe[sub.3]O[sub.4], the Fe[sub.3]O[sub.4]@SiO[sub.2]@Au/PDA nanochain showed a typical soft magnetic behavior. Both the NIR and magnetic field affected the antimicrobial performance of the Fe[sub.3]O[sub.4]@SiO[sub.2]@Au/PDA nanochains. Escherichia coli and Staphylococcus aureus were used as models to verify the antibacterial properties. The experimental results showed that the Fe[sub.3]O[sub.4]@SiO[sub.2]@Au/PDA nanochains exhibited good antibacterial properties under photothermal conditions. After applying a magnetic field, the bactericidal effect was further significantly enhanced. The above results show that the material has a broad application prospect in inhibiting the growth of bacteria.