title: Biological reduction of nanoengineered iron(III) oxide sculptured thin films.
abstract: Sculptured thin films (STFs) are assemblies of nominally identical, parallel nanowires with tailored shapes such as chevrons and spirals. A series of iron(lll) STFs were produced with varied crystallinity (from hematite toferrihydrite) and nanowire shapes (slanted columnar, clockwise helical, and counterclockwise helical). When the dissimilatory metal-reducing bacterium Shewanella putrefaciens CN32 was used to measure their bioreducibility, it was found that bioreduction was controlled primarily by oxide crystallinity. STFs were characterized by scanning electron microscopy, atomic force microscopy, and grazing incidence small-angle X-ray scattering. Postbioreduction characterizations determined that mineralogy of the film materials did not change, but surface roughness generally increased. Changes caused by bioreduction were assessed in terms of both transmittance and reflectance of light incident normal to the STFs. The greatest optical changes were obtained with crystalline hematite films. These results underscore the feasibility of an STF-based fiber optic iron(lll) reduction sensor for in situ subsurface deployment.
authors.affiliation: Department of Civil and Environmental Engineering, 212 Sackett Building, The Pennsylvania State University, University Park, Pennsylvania 16802-1408, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Tan
authors.forename: Obiefune K
authors.initials: OK
authors.lastname: Ezekoye
authors.forename: James
authors.initials: J
authors.lastname: Van der Schalie
authors.forename: Mark W
authors.initials: MW
authors.lastname: Horn
authors.forename: Akhlesh
authors.initials: A
authors.lastname: Lakhtakia
authors.forename: Jian
authors.initials: J
authors.lastname: Xu
authors.forename: William D
authors.initials: WD
authors.lastname: Burgos
mesh_terms: D005290:Ferric Compounds / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D036103:Nanotechnology; D020614:Shewanella putrefaciens / Q000378:metabolism*
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide