title: Wavelength and orientation dependent capture of light by diatom frustule nanostructures.
abstract: The ecological success of diatoms is emphasized by regular blooms of many different species in all aquatic systems, but the reason behind their success is not fully understood. A special feature of the diatom cell is the frustule, a nano-patterned cell encasement made of amorphous biosilica. The optical properties of a cleaned single valve (one half of a frustule) from the diatom Coscinodiscus centralis were studied using confocal micro-spectroscopy. A photonic crystal function in the frustule was observed, and analysis of the hyperspectral mapping revealed an enhancement of transmitted light around 636 and 663 nm. These wavelengths match the absorption maxima of chlorophyll a and c, respectively. Additionally, we demonstrate that a highly efficient light trapping mechanism occurred, resulting from strong asymmetry between the cribrum and foramen pseudo-periodic structures. This effect may prevent transmitted light from being backscattered and in turn enhance the light absorption. Based on our results, we hypothesize that the multi-scaled layered structure of the frustule improves photosynthetic efficiency by these three mechanisms. The optical properties of the frustule described here may contribute to the ecological success of diatoms in both lentic and marine ecosystems, and should be studies further in vivo.
authors.affiliation: Department of Material Science and Engineering, Norwegian University of Science and Technology NTNU, NO-7491 Trondheim, Norway.
authors.forename: Julien
authors.initials: J
authors.lastname: Romann
authors.affiliation: IM2NP UMR 7334 CNRS, Université de Toulon, P.O. Box 20132, 83957 La Garde Cedex, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Valmalette
authors.affiliation: Department of Biotechnology, Norwegian University of Science and Technology NTNU, NO-7491 Trondheim, Norway.
authors.forename: Matilde Skogen
authors.initials: MS
authors.lastname: Chauton
authors.affiliation: Department of Material Science and Engineering, Norwegian University of Science and Technology NTNU, NO-7491 Trondheim, Norway.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Tranell
authors.affiliation: Department of Material Science and Engineering, Norwegian University of Science and Technology NTNU, NO-7491 Trondheim, Norway.
authors.forename: Mari-Ann
authors.initials: MA
authors.lastname: Einarsrud
authors.affiliation: Department of Biotechnology, Norwegian University of Science and Technology NTNU, NO-7491 Trondheim, Norway.
authors.forename: Olav
authors.initials: O
authors.lastname: Vadstein
mesh_terms: D017377:Diatoms / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D017753:Ecosystem; D008027:Light; D049329:Nanostructures / Q000737:chemistry / Q000648:ultrastructure; D010788:Photosynthesis / Q000502:physiology*; D012822:Silicon Dioxide / Q000737:chemistry / Q000378:metabolism
chemical_list: D012822:Silicon Dioxide