Solid-state NMR spectroscopic studies of 13 C, 15 N, 29 Si-enriched biosilica from the marine diatom Cyclotella cryptica
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Solid‑state NMR spectroscopic studies of 13C,15N,29Si‑enriched biosilica from the marine diatom Cyclotella cryptica Felicitas Kolbe1 · Helena Leona Ehren2 · Simon Kohrs1 · Daniel Butscher1 · Lukas Reiß1,3 · Marc Baldus2 · Eike Brunner1 Received: 25 June 2020 / Accepted: 20 November 2020 © The Author(s) 2020 OPEN
Abstract Diatoms are algae producing micro- and nano-structured cell walls mainly containing amorphous silica. The shape and patterning of these cell walls is species-specific. Herein, the biosilica of Cyclotella cryptica, a centric marine diatom with a massive organic matrix, is studied. Solid-state NMR spectroscopy is applied to gain deeper insight into the interactions at the organic–inorganic interface of the cell walls. The various organic compounds like polysaccharides as well as proteins and long-chain polyamines (LCPAs) are detected by observation of heteronuclei like 13C and 15N whereas the silica phase is studied using 29Si NMR spectroscopy. The sensitivity of the NMR experiments is strongly enhanced by isotope-labeling of the diatoms during cultivation with 13C, 15N and 29Si. The presence of two different chitin species in the biosilica is demonstrated. This observation is supported by a monosaccharide analysis of the silica-associated organic matrix where a high amount of glucosamine is found. Moreover, the Rotational Echo Double Resonance (REDOR) experiment provides distance information for heteronuclear spins. 13C{29Si} REDOR experiments reveal proximities between different organic compounds and the silica phase. The closest contacts between silica and organic compounds appear for different signals in the 13C-chemical shift range of 40–60 ppm, the typical range for LCPAs. Keywords Solid-state NMR spectroscopy · REDOR · Diatoms · Cyclotella cryptica · Chitin Abbreviations 2D Two-dimensional ASW Artificial seawater C. cryptica Cyclotella cryptica CP Cross polarization EDTA Ethylenediaminetetraacetic acid EI Electron impact ESI Electronic supporting information GC Gas chromatography GFP Green fluorescent protein
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s43939-020-00003-7) contains supplementary material, which is available to authorized users. * Eike Brunner, eike.brunner@tu‑dresden.de; Felicitas Kolbe, felicitas.kolbe@tu‑dresden.de; Helena Leona Ehren, [email protected]; Simon Kohrs, [email protected]; Daniel Butscher, daniel.butscher@tu‑dresden.de; Lukas Reiß, reiss@hfbk‑dresden.de; Marc Baldus, [email protected] | 1Chair of Bioanalytical Chemistry, Faculty of Chemistry and Food Chemistry, TU Dresden, 01062 Dresden, Germany. 2NMR Spectroscopy, Bijvoet Center for Biomolecular Research Utrecht University, 3584 CH Utrecht, The Netherlands. 3Present Address: Hochschule Für Bildende Künste (HfBK) Dresden, Güntzstraße 34, 01307 Dresden, Germany. Discover Materials
(2021) 1:3
| https://doi.org/10.1007/s43939-020-00003-7
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Discover Materials
(2021) 1:3
| https://doi.org/10.1007/s43939-020-00003-7
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