title: Electronically transparent graphene replicas of diatoms: a new technique for the investigation of frustule morphology.
abstract: The morphogenesis of the silica cell walls (called frustules) of unicellular algae known as diatoms is one of the most intriguing mysteries of the diatoms. To study frustule morphogenesis, optical, electron and atomic force microscopy has been extensively used to reveal the frustule morphology. However, since silica frustules are opaque, past observations were limited to outer and fracture surfaces, restricting observations of interior structures. Here we show that opaque silica frustules can be converted into electronically transparent graphene replicas, fabricated using chemical vapor deposition of methane. Chemical vapor deposition creates a continuous graphene coating preserving the frustule's shape and fine, complicated internal features. Subsequent dissolution of the silica with hydrofluoric acid yields a free-standing replica of the internal and external native frustule morphologies. Electron microscopy renders these graphene replicas highly transparent, revealing previously unobserved, complex, three-dimensional, interior frustule structures, which lend new insights into the investigation of frustule morphogenesis.
authors.affiliation: 1] College of Engineering, University of Georgia, Athens, GA 30602, USA [2] Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA.
authors.forename: Zhengwei
authors.initials: Z
authors.lastname: Pan
authors.affiliation: Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Sarah J L
authors.initials: SJ
authors.lastname: Lerch
authors.affiliation: 1] College of Engineering, University of Georgia, Athens, GA 30602, USA [2].
authors.forename: Liang
authors.initials: L
authors.lastname: Xu
authors.affiliation: 1] College of Engineering, University of Georgia, Athens, GA 30602, USA [2].
authors.forename: Xufan
authors.initials: X
authors.lastname: Li
authors.affiliation: College of Engineering, University of Georgia, Athens, GA 30602, USA.
authors.forename: Yen-Jun
authors.initials: YJ
authors.lastname: Chuang
authors.affiliation: 1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA [2].
authors.forename: Jane Y
authors.initials: JY
authors.lastname: Howe
authors.affiliation: Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Mahurin
authors.affiliation: Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
authors.forename: Sheng
authors.initials: S
authors.lastname: Dai
authors.affiliation: Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Hildebrand
mesh_terms: D017377:Diatoms / Q000737:chemistry* / Q000378:metabolism; D005740:Gases / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D006858:Hydrofluoric Acid / Q000737:chemistry; D008697:Methane / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D012822:Silicon Dioxide / Q000737:chemistry; D013059:Spectrum Analysis, Raman
chemical_list: D005740:Gases; D012822:Silicon Dioxide; D006108:Graphite; D008697:Methane; D006858:Hydrofluoric Acid