title: The antibacterial properties of a novel chitosan-Ag-nanoparticle composite.
abstract: Escherichia coli expressing recombinant green fluorescent protein was used to test the bactericidal efficacy of a newly synthesized chitosan-Ag-nanoparticle composite. The composite was found to have significantly higher antimicrobial activity than its components at their respective concentrations. The one-pot synthesis method led to the formation of small Ag nanoparticles attached to the polymer which can be dispersed in media of pH< or =6.3. The presence of a small percentage (2.15%, w/w) of metal nanoparticles in the composite was enough to significantly enhance inactivation of E. coli as compared with unaltered chitosan. Fluorescence spectroscopy indicated that bacterial growth stopped immediately after exposure of E. coli to the composite, with release of cellular green fluorescent protein into the medium at a faster rate than with chitosan. Fluorescence confocal laser scanning and scanning electron microscopy showed attachment of the bacteria to the composite and their subsequent fragmentation. Native protein gel electrophoresis experiments indicated no effect of the composite on bacterial proteins.
authors.affiliation: Centre for Nanotechnology, Indian Institute of Technology-Guwahati, Guwahati, India.
authors.forename: Pallab
authors.initials: P
authors.lastname: Sanpui
authors.forename: A
authors.initials: A
authors.lastname: Murugadoss
authors.forename: P V Durga
authors.initials: PV
authors.lastname: Prasad
authors.forename: Siddhartha Sankar
authors.initials: SS
authors.lastname: Ghosh
authors.forename: Arun
authors.initials: A
authors.lastname: Chattopadhyay
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D048271:Chitosan / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D049452:Green Fluorescent Proteins / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000648:ultrastructure; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D036103:Nanotechnology; D010316:Particle Size; D011108:Polymers; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D011108:Polymers; D049452:Green Fluorescent Proteins; D012834:Silver; D048271:Chitosan