title: Sequential laser and ultrasonic wave generation of TiO2@Ag core-shell nanoparticles and their anti-bacterial properties.
abstract: Core-shell nanoparticles have unusual physical, chemical and biological properties. Until now, for the Ag and TiO2 combination, only Ag core and TiO2 shell nanoparticles have been practically demonstrated. In this investigation, novel TiO2@Ag core-shell (TiO2 core and Ag shell) nanoparticles were produced via ultrasonic vibration of Ag-TiO2 compound nanoparticles. A bulk Ti/Ag alloy plate was used to generate colloidal Ag-TiO2 compound nanoparticles via picosecond laser ablation in deionised water. The colloidal nanoparticles were then sonicated in an ultrasonic bath to generate TiO2@Ag core-shell nanoparticles. They were characterised using a UV-VIS spectrometer, transmission electron microscopy (TEM), high-angle annular dark-field-Scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The Ag-TiO2 compound and the TiO2@Ag core-shell nanoparticles were examined for their antibacterial activity against Escherichia coli (E. coli) JM109 strain bacteria and compared with those of Ag and TiO2 nanoparticles. The antibacterial activity of the core-shell nanoparticles was slightly better than that of the compound nanoparticles at the same concentration under standard laboratory light conditions and both were better than the TiO2 nanoparticles but not as good as the Ag nanoparticles.
authors.affiliation: Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester, M13 9PL, UK. abubaker.hamad75@yahoo.co.uk.
authors.forename: Abubaker Hassan
authors.initials: AH
authors.lastname: Hamad
authors.affiliation: Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester, M13 9PL, UK.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.affiliation: School of Materials, The University of Manchester, Manchester, M13 9PL, UK.
authors.forename: Zhu
authors.initials: Z
authors.lastname: Liu
authors.affiliation: School of Materials, The University of Manchester, Manchester, M13 9PL, UK.
authors.forename: Xiang Li
authors.initials: XL
authors.lastname: Zhong
authors.affiliation: Faculty of Medical and Human Sciences, The University of Manchester, Manchester, M13 9PL, UK.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects; D007834:Lasers; D008027:Light; D053758:Nanoparticles; D036103:Nanotechnology; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology*; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D000069453:Ultrasonic Waves
chemical_list: D000900:Anti-Bacterial Agents; C009495:titanium dioxide; D012834:Silver; D014025:Titanium
keywords: Ag-TiO2 compound nanoparticles; Antibacterial activity; Laser ablation; TiO2@Ag core-shell nanoparticles