title: Core-shell-shell nanorods for controlled release of silver that can serve as a nanoheater for photothermal treatment on bacteria.
abstract: A novel bactericidal material comprising rod-shaped core-shell-shell Au-Ag-Au nanorods is constructed as a nanoheater in the near-infrared (NIR) region. The outer Au shell melts under laser irradiation and results in exposure of the inner Ag shell, facilitating the controlled release of the antibacterial Ag shell/layer or Ag(+). This results in the Au-Ag-Au nanorods having a favorable bactericidal ability as it combines the features of physical photothermal ablation sterilization of the outer Au shell and the antibacterial effect of the inner Ag shell or Ag(+) to the surrounding bacteria. The sterilizing ability of Au-Ag-Au nanorods is investigated with Escherichia coli O157:H7 as a model bacterial strain. Under low-power NIR laser irradiation (785 nm, 50 mW cm(-2)), the Au-Ag-Au nanoheater exhibits a higher photothermal conversion efficiency (with a solution temperature of 44°C) with respect to that for the Au-Ag nanorods (39°C). Meanwhile, a much improved stability with respect to Au-Ag nanorods is observed, i.e., 16 successive days of monitoring reveal virtually no change in the ultraviolet-visible spectrum of Au-Ag-Au nanorods, while a significant drop in absorption along with a 92 nm red shift of Localized Surface Plasmon Resonance is recorded for the Au-Ag nanorods. This brings an increasing bactericidal efficiency and long-term stability for the Au-Ag-Au nanorods. At a dosage of 10 μg ml(-1), a killing rate of 100% is reached for the E. coli O157:H7 cells under 20 min of irradiation. The use of Au-Ag-Au nanorods avoids the abuse of broad-spectrum antibiotics and reduces the damage of tissues by alleviating the toxicity of silver under controlled release and by the use of low-power laser irradiation. These features could make the bimetallic core-shell-shell nanorods a favorable nanoheater for in vivo biomedical applications.
authors.affiliation: Research Center for Analytical Sciences, College of Sciences, Northeastern University, Box 332, Shenyang 110819, People's Republic of China.
authors.forename: Bo
authors.initials: B
authors.lastname: Hu
authors.affiliation: Research Center for Analytical Sciences, College of Sciences, Northeastern University, Box 332, Shenyang 110819, People's Republic of China.
authors.forename: Ning
authors.initials: N
authors.lastname: Wang
authors.affiliation: Research Center for Analytical Sciences, College of Sciences, Northeastern University, Box 332, Shenyang 110819, People's Republic of China.
authors.forename: Lu
authors.initials: L
authors.lastname: Han
authors.affiliation: Research Center for Analytical Sciences, College of Sciences, Northeastern University, Box 332, Shenyang 110819, People's Republic of China. Electronic address: chenml@mail.neu.edu.cn.
authors.forename: Ming-Li
authors.initials: ML
authors.lastname: Chen
authors.affiliation: Research Center for Analytical Sciences, College of Sciences, Northeastern University, Box 332, Shenyang 110819, People's Republic of China; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300071, People's Republic of China. Electronic address: jianhuajrz@mail.neu.edu.cn.
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Wang
mesh_terms: D065966:Absorption, Physicochemical; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000737:chemistry; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D003692:Delayed-Action Preparations / Q000008:administration & dosage / Q000737:chemistry*; D004058:Diffusion; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects*; D006358:Hot Temperature; D053769:Nanocapsules / Q000008:administration & dosage / Q000737:chemistry / Q000648:ultrastructure; D058608:Nanopores / Q000648:ultrastructure; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D016062:Porosity; D012834:Silver / Q000008:administration & dosage* / Q000737:chemistry; D013242:Sterilization / Q000379:methods*
chemical_list: D000900:Anti-Bacterial Agents; D003692:Delayed-Action Preparations; D053769:Nanocapsules; D012834:Silver
keywords: Controlled release; Gold–silver–gold nanorods; NIR photothermal treatment; Rod-shaped core–shell–shell nanomaterials