Multifunctional Fe 3 O 4 Nanoparticles Filled Polydopamine Hollow Rods for Antibacterial Biofilm Treatment.

This work reports the use of mesoporous silica rods as templates for the step-wise preparation of multifunctional Fe ₃ O ₄ NPs filled polydopamine hollow rods (Fe ₃ O ₄ @PDA HR). The capacity of as-synthesized Fe ₃ O ₄ @PDA HR as a new drug carrier platform was assessed by its loading and the triggered release of fosfomycin under various stimulations. It was found that the release of fosfomycin was pH dependent with ~89% of fosfomycin being released in pH 5 after 24 h, which was 2-fold higher than that in pH 7. The magnetic properties of Fe ₃ O ₄ NPs and the photothermal properties of PDA enabled the triggered release of fosfomycin upon the exposure to rotational magnetic field, or NIR laser irradiation. Additionally, the capability of using multifunctional Fe ₃ O ₄ @PDA HR to eliminate preformed bacterial biofilm was demonstrated. Upon exposure to the rotational magnetic field, the biomass of a preformed biofilm was significantly reduced by 65.3% after a 20 min treatment with Fe ₃ O ₄ @PDA HR. Again, due to the excellent photothermal properties of PDA, a dramatic biomass decline (72.5%) was achieved after 10 min of laser exposure. This study offers an alternative approach of using drug carrier platform as a physical mean to kill pathogenic bacteria along with its traditional use for drug delivery.