Dipolar-hollowed α-Fe₂O₃@Au/Polydopamine nanospindle for photothermal-photodynamic coupling antibacterial and drug-delivery

With the prevalence of drug-resistant bacteria and the waning effects of antibiotics, nanoplatform has become an effective strategy for fighting infections. This work reports a dipolar-hollowed α-Fe₂O₃@Au/Polydopamine (PDA) nanospindle which possesses both photothermal-photodynamic (PTT-PDT) coupling antibacterial and drug carrying performance. Firstly, the spindle type α-Fe₂O₃@Au/PDA particle was prepared by a simple one-step strategy and then the dipolar-hollow structure was obtained by controlling etching the inside α-Fe₂O₃ core with hydrochloric acid. After further loading the photosensitizer zinc phthalocyanine (ZnPc), the dipolar-hollowed α-Fe₂O₃@Au/PDA-ZnPc nanospindles were obtained. Owing to the dipolar-hollowed interior, the nanospindles are also effective in carrying antitumor drug doxorubicin (DOX) and shows a good drug loading-release behavior. The dipolar-hollowed α-Fe₂O₃@Au/PDA nanospindles exhibits a high antibacterial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under near-infrared (NIR) and Xenon lamp irradiation. When α-Fe₂O₃@Au/PDA-ZnPc nanospindles concentration was increased to 100 μg/mL, the antibacterial rate was close to 100 %. In comparison to the original α-Fe₂O₃@Au/PDA nanospindles, the product achieved a lower effective antibacterial temperature. This triple-mode therapy (PTT/PDT/Drug) provides an interesting design idea for anisotropic therapeutic nanoplatform which can be applied in low-temperature antibacterial and drug delivery.