title: Internal structure of sponge glass fiber revealed by ptychographic nanotomography.
abstract: Sponge glass spicules have solicited great interest due to their mechanical and optical properties. Herein we use ptychographic nanotomography to obtain detailed insights into the internal structure of an anchor spicule from the Venus flower basket. The obtained dataset has 90nm resolution in 3D and provides quantitative determination of the electron density. The data reveal significant variations in electron density across the spicule. The central organic filament is found to be slightly but significantly displaced from the spicule central axis. Analysis of the electron density affords an estimate of a protein volume fraction in the organic filament of about 70%. In the highly mineralized part of the spicule, the electron density is seen to display circular symmetry and be neigh independent of position along the spicule long axis. Variations in the electron density beyond those included in current models of spicule mechanics are observed.
authors: iNANO and Department of Chemistry, Aarhus University, 14 Gustav Wieds Vej, 8000 Aarhus, Denmark.
authors: Mie E
authors: ME
authors: Birkbak
authors: Paul Scherrer Institut, 5332 Villigen PSI, Switzerland.
authors: Manuel
authors: M
authors: Guizar-Sicairos
authors: Paul Scherrer Institut, 5332 Villigen PSI, Switzerland.
authors: Mirko
authors: M
authors: Holler
authors: iNANO and Department of Chemistry, Aarhus University, 14 Gustav Wieds Vej, 8000 Aarhus, Denmark. Electronic address: hbirkedal@chem.au.dk.
authors: Henrik
authors: H
authors: Birkedal
mesh_terms: D000818:Animals; D003952:Diagnostic Imaging / Q000379:methods; D005898:Glass / Q000737:chemistry*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008855:Microscopy, Electron, Scanning; D011161:Porifera / Q000737:chemistry* / Q000648:ultrastructure; D012822:Silicon Dioxide / Q000737:chemistry*; D055114:X-Ray Microtomography / Q000379:methods*
chemical_list: C009753:fiberglass; D012822:Silicon Dioxide
keywords: Biomineralization; Ptychography; Silica; Sponge; X-ray imaging