Shewanella-mediated synthesis of selenium nanowires and nanoribbons

Amorphous selenium nanospheres, originally produced by Shewanella sp. strain HN-41 under anaerobic conditions, can be rapidly transformed into extensive, long and thin, polycrystalline Se nanowires and nanoribbons (>100 mu m x 57 nm) in 80% DMSO with bacterial pellets at physiological temperature. Scanning and transmission electron microscopic analyses indicated that the Se nanowires and nanospheres were crystalline structures indexed into the hexagonal plane of Se. The structures possessed an unusually high crystalline peak ( 100), suggesting a preferential [ 001] growth direction. Electron micrographic analyses and incubation studies suggested that the cell membrane of the Shewanella sp. strain HN-41 likely plays an important role in the formation of amorphous Se nanospheres from soluble Se(IV) and the formation of long and thin h-Se nanowires and nanoribbons. The formation of zero- and one-dimensional h-Se nanostructures by this bacterium may provide a facile strategy to recover soluble Se(IV) from the environment and generate new materials that will be useful for advanced nanotechnologies.