Silica Nanotubes and Nanohole Arrays Templated by Genetically Engineered Bacterial Flagella
F. Wang, D. Li, C. Mao
University of Oklahoma, US
Keywords: bacterial flagella, nanotubes, silica, nanoholes
Abstract:Bacterial flagellum is a protein nanotube that is helically self-assembled from thousands of a protein subunit called flagellin. The solvent-exposed domain of each flagellin is genetically modifiable in that a foreign peptide can be genetically inserted into this domain, leading to the high-density display of this peptide on the flagella. In this work, wild-type and genetically engineered flagella (inner diameter of ~2 nm and outer diameter of ~14 nm) detached from the surface of Salmonella bacterial cells were used as templates to site-specifically form silica sheath on the flagella surface, resulting in the double-layered silica/flagella nanotubes. The flagella templates inside the silica/flagella nanotubes can be removed to obtain silica nanotubes by calcining the nanotubes at high temperature. The further calcination of the silica nanotubes at a higher temperature leads to the formation of a periodic nanohole array along the silica fibers with a center-to-center nanohole spacing of ~79 nm. Our work suggests that the monodisperse diameter and genetically tunable surface chemistry of the flagella can be exploited for the fabrication of nanotubes with uniform morphologies as well periodic nanohole arrays. The silica/flagella hybrid nanotubes, silica nanotubes and nanoholed silica nanofibers will find potential applications in nanofluidics, photonics and nanomedicine.