title: Monodispersed biocompatible silver sulfide nanoparticles: facile extracellular biosynthesis using the γ-proteobacterium, Shewanella oneidensis.
abstract: Interest in engineered metal and semiconductor nanocrystallites continues to grow due to their unique size- and shape-dependent optoelectronic, physicochemical and biological properties. Therefore identifying novel non-hazardous nanoparticle synthesis routes that address hydrophilicity, size and shape control and production costs has become a priority. In the present article we report for the first time on the efficient generation of extracellular silver sulfide (Ag₂S) nanoparticles by the metal-reducing bacterium Shewanella oneidensis. The particles are reasonably monodispersed and homogeneously shaped. They are produced under ambient temperatures and pressures at high yield, 85% theoretical maximum. UV-visible and Fourier transform infrared spectroscopy, dynamic light scattering, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy measurements confirmed the formation, optical and surface properties, purity and crystallinity of the synthesized particles. Further characterization revealed that the particles consist of spheres with a mean diameter of 9±3.5 nm, and are capped by a detachable protein/peptide surface coat. Toxicity assessments of these biogenic Ag₂S nanoparticles on Gram-negative (Escherichia coli and S. oneidensis) and Gram-positive (Bacillus subtilis) bacterial systems, as well as eukaryotic cell lines including mouse lung epithelial (C 10) and macrophage (RAW-264.7) cells, showed that the particles were non-inhibitory and non-cytotoxic to any of these systems. Our results provide a facile, eco-friendly and economical route for the fabrication of technologically important semiconducting Ag₂S nanoparticles. These particles are dispersible and biocompatible, thus providing excellent potential for use in optical imaging, electronic devices and solar cell applications.
authors.affiliation: Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. sureshak@ornl.gov
authors.forename: Anil K
authors.initials: AK
authors.lastname: Suresh
authors.forename: Mitchel J
authors.initials: MJ
authors.lastname: Doktycz
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Ji-Won
authors.initials: JW
authors.lastname: Moon
authors.forename: Baohua
authors.initials: B
authors.lastname: Gu
authors.forename: Harry M
authors.initials: HM
authors.lastname: Meyer
authors.forename: Dale K
authors.initials: DK
authors.lastname: Hensley
authors.forename: David P
authors.initials: DP
authors.lastname: Allison
authors.forename: Tommy J
authors.initials: TJ
authors.lastname: Phelps
authors.forename: Dale A
authors.initials: DA
authors.lastname: Pelletier
mesh_terms: D001672:Biocompatible Materials; D053768:Metal Nanoparticles; D056951:Photoelectron Spectroscopy; D020592:Shewanella / Q000378:metabolism*; D018030:Silver Compounds / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D018030:Silver Compounds; C013251:silver sulfide