title: Ex situ formation of metal selenide quantum dots using bacterially derived selenide precursors.
abstract: Luminescent quantum dots were synthesized using bacterially derived selenide (Se(II-)) as the precursor. Biogenic Se(II-) was produced by the reduction of Se(IV) by Veillonella atypica and compared directly against borohydride-reduced Se(IV) for the production of glutathione-stabilized CdSe and β-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological Se(II-) formed smaller, narrower size distributed QDs under the same conditions. The growth kinetics of biologically sourced CdSe phases were slower. The proteins isolated from filter sterilized biogenic Se(II-) included a methylmalonyl-CoA decarboxylase previously characterized in the closely related Veillonella parvula. XAS analysis of the glutathione-capped CdSe at the S K-edge suggested that sulfur from the glutathione was structurally incorporated within the CdSe. A novel synchrotron based XAS technique was also developed to follow the nucleation of biological and inorganic selenide phases, and showed that biogenic Se(II-) is more stable and more resistant to beam-induced oxidative damage than its inorganic counterpart. The bacterial production of quantum dot precursors offers an alternative, 'green' synthesis technique that negates the requirement of expensive, toxic chemicals and suggests a possible link to the exploitation of selenium contaminated waste streams.
authors.affiliation: School of Earth, Atmospheric and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, Williamson Building, University of Manchester, Oxford Road, Manchester, M13 9PL, UK. Jonathan.Fellowes@manchester.ac.uk
authors.forename: J W
authors.initials: JW
authors.lastname: Fellowes
authors.forename: R A D
authors.initials: RA
authors.lastname: Pattrick
authors.forename: J R
authors.initials: JR
authors.lastname: Lloyd
authors.forename: J M
authors.initials: JM
authors.lastname: Charnock
authors.forename: V S
authors.initials: VS
authors.lastname: Coker
authors.forename: J F W
authors.initials: JF
authors.lastname: Mosselmans
authors.forename: T-C
authors.initials: TC
authors.lastname: Weng
authors.forename: C I
authors.initials: CI
authors.lastname: Pearce
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D019187:Cadmium Compounds / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D049449:Luminescence; D043586:Methylmalonyl-CoA Decarboxylase / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D036103:Nanotechnology; D010084:Oxidation-Reduction; D010316:Particle Size; D045663:Quantum Dots; D018036:Selenium Compounds / Q000378:metabolism*; D017356:Synchrotrons; D014678:Veillonella / Q000378:metabolism; D056928:X-Ray Absorption Spectroscopy
chemical_list: D001426:Bacterial Proteins; D019187:Cadmium Compounds; D018036:Selenium Compounds; C058667:cadmium selenide; D043586:Methylmalonyl-CoA Decarboxylase; D005978:Glutathione