title: Magnetic nanohybrids loaded with bimetal core-shell-shell nanorods for bacteria capture, separation, and near-infrared photothermal treatment.
abstract: A novel antimicrobial nanohybrid based on near-infrared (NIR) photothermal conversion is designed for bacteria capture, separation, and sterilization (killing). Positively charged magnetic reduced graphene oxide with modification by polyethylenimine (rGO-Fe3 O4 -PEI) is prepared and then loaded with core-shell-shell Au-Ag-Au nanorods to construct the nanohybrid rGO-Fe3 O4 -Au-Ag-Au. NIR laser irradiation melts the outer Au shell and exposes the inner Ag shell, which facilitates controlled release of the silver shell. The nanohybrids combine physical photothermal sterilization as a result of the outer Au shell with the antibacterial effect of the inner Ag shell. In addition, the nanohybrid exhibits high heat conductivity because of the rGO and rapid magnetic-separation capability that is attributable to Fe3 O4 . The nanohybrid provides a significant improvement of bactericidal efficiency with respect to bare Au-Ag-Au nanorods and facilitates the isolation of bacteria from sample matrixes. A concentration of 25 μg mL(-1) of nanohybrid causes 100 % capture and separation of Escherichia coli O157:H7 (1×10(8) cfu mL(-1) ) from an aqueous medium in 10 min. In addition, it causes a 22 °C temperature rise for the surrounding solution under NIR irradiation (785 nm, 50 mW cm(-2) ) for 10 min. With magnetic separation, 30 μg mL(-1) of nanohybrid results in a 100 % killing rate for E. coli O157:H7 cells. The facile bacteria separation and photothermal sterilization is potentially feasible for environmental and/or clinical treatment.
authors.affiliation: Research Center for Analytical Sciences, College of Sciences, Box 332, Northeastern University, Shenyang 110819 (P.R. China); Department of Biochemistry and Molecular Biology, China Medical University, Shenyang 110122 (P.R. China).
authors.forename: Bo
authors.initials: B
authors.lastname: Hu
authors.forename: Ning
authors.initials: N
authors.lastname: Wang
authors.forename: Lu
authors.initials: L
authors.lastname: Han
authors.forename: Ming-Li
authors.initials: ML
authors.lastname: Chen
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Wang
mesh_terms: D004926:Escherichia coli / Q000528:radiation effects*; D006046:Gold / Q000737:chemistry; D006108:Graphite / Q000737:chemistry; D008280:Magnetics; D043942:Nanotubes; D012834:Silver / Q000737:chemistry; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D012834:Silver; D006046:Gold; D006108:Graphite
keywords: gold; magnetic properties; nanostructures; photothermal treatment; silver