title: Ag colloids and Ag clusters over EDAPTMS-coated silica nanoparticles: synthesis, characterization, and antibacterial activity against Escherichia coli.
abstract: To produce better antibacterial water-insoluble nanocomposites of silver (Ag), silver-silicon dioxide (Ag-SiO(2)) hybrid and silver colloid (Ag-c) nanoparticles (NPs) were studied. Ag-c NPs were synthesized using reduction of AgNO(3), and Ag-SiO(2) composites were prepared on a core of silica NPs functionalized with ethylenediamino-propyltrimethoxysilane, where Ag clusters were fabricated on amino groups using seed-mediated growth and characterized by transmission electron microscopy and ultraviolet-visible absorption spectroscopy. Antibacterial effectiveness of the Ag-SiO(2) NPs was tested against general Escherichia coli (E. coli ATCC 25922) and E. coli O157:H7 by measuring the growth based on optical density and digital counting of live-dead cells using a fluorescent microscope, and a field emission scanning electron microscope. Minimum inhibitory concentration values were studied against four representative bacteria along with E. coli O157:H7. Results showed that Ag NPs of 6.6 ± 4.5 nm were attached to the surface of SiO(2) NPs (74 ± 13.5 nm), and the Ag-c NPs (3.5 ± 2 nm) showed excellent antibacterial properties.
  
  
  BACKGROUND
  In this paper, the synthesis of Ag colloids and Ag clusters over EDAPTMS-coated silica nanoparticles is reported. Both NPs were examined for antibacterial effectiveness against representative bacteria including E. coli O157:H7 and found to have excellent antibacterial properties.
authors.affiliation: Biosensors and Nanotechnology Application Laboratory (BNAL), University of Idaho, Coeur D'Alene, Coeur d'Alene, Idaho, USA. srastogi@uidaho.edu
authors.forename: Shiva K
authors.initials: SK
authors.lastname: Rastogi
authors.forename: Veronica J
authors.initials: VJ
authors.lastname: Rutledge
authors.forename: CharLene
authors.initials: C
authors.lastname: Gibson
authors.forename: David A
authors.initials: DA
authors.lastname: Newcombe
authors.forename: Josh R
authors.initials: JR
authors.lastname: Branen
authors.forename: A Larry
authors.initials: AL
authors.lastname: Branen
mesh_terms: D000900:Anti-Bacterial Agents / Q000138:chemical synthesis* / Q000494:pharmacology*; D003102:Colloids; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000648:ultrastructure; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D008856:Microscopy, Fluorescence; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D012821:Silanes / Q000737:chemistry*; D012822:Silicon Dioxide / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D012834:Silver / Q000494:pharmacology*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000900:Anti-Bacterial Agents; D003102:Colloids; D012821:Silanes; C492568:propyltrimethoxysilane; D012834:Silver; D012822:Silicon Dioxide