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Biomineralization products

Electron microscopic image of mandibles from Calanoides acutus (SE-Image 2,0 keV, WD 8,0 mm)
Electron microscopic image of mandibles from Calanoides acutus (BSE-Image)

Biominerals with outstanding properties are synthesized by nature under moderate conditions. Up to now only in few cases biosynthetic pathways are completely enlightened and even for these materials reproduction of the synthesis under laboratory conditions is very difficult. For or during this synthesis a bioaccumulation of trace elements often takes place together with the formation of biocomposite materials in which inorganic and organic materials are combined at the nanometer scale in a certain way. These products are responsible for the resulting improvements in hardness, flexibility, specific weight, colour or haptics, to name only few.  Thus a detailed investigation of composition and structure of these materials down to the nanometer scale is a prerequisite to understand the mechanism of their formation.

Copepods are usually the dominant members of the zooplankton, and are major food organisms for small fish. Copepods are important to global ecology and the carbon cycle, therefore investigation of their nutrition behavior helps to understand the ecological importance for the region in question. The mandibles at the end of the gnathobases of the copepods are especially important since they play a particular role in the acquisition of food. The morphology of these gnathobases, but also composition of the biomaterial from which they are built differ in dependence on the diet (herbivorous, carnivorous, omnivorous). Several species which feed on hard diet are able to enrich silica at the tip of the mandibles thus producing much harder, long-life teeth and tips zo catch, hold and cutting off the pray.

For an investigation of these biomaterials at the µm- and sub-µm scale sensitive analytical methods are required. Solid state analysis could be performed with Proton/Particle induced X-ray emission (PIXE) and laser ablation coupled to inductively coupled plasma mass spectrometry (LA-ICP-MS) with LODs in the µg/g region or below. External quantification with matrix-matched reference materials (CaCO3/Chitin/Chitosan) guaranties correct results due to comparable interaction of proton or laser beam with the materials in sample and reference. Sample preparation is demanding due to the irregular shape and small size (50-200 µm) of the gnathobases which have to be separated from the copepod body under the microscope prior to fixation on a suitable sample holder.

 

 

Images left column 300 x 300 µm, right column enlargement oft he two outermost teeth, image size 50 x 50 µm. (PIXE Analysis at Hochenergie Ionennanosonde LIPSION (Uni Leipzig) 2.25 MeV; 100-300 pA

For an investigation of these biomaterials at the µm- and sub-µm scale sensitive analytical methods are required. Solid state analysis could be performed with Proton/Particle induced X-ray emission (PIXE) and laser ablation coupled to inductively coupled plasma mass spectrometry (LA-ICP-MS) with LODs in the µg/g region or below. External quantification with matrix-matched reference materials (CaCO3/Chitin/Chitosan) guaranties correct results due to comparable interaction of proton or laser beam with the materials in sample and reference. Sample preparation is demanding due to the irregular shape and small size (50-200 µm) of the gnathobases which have to be separated from the copepod body under the microscope prior to fixation on a suitable sample holder.

Investigations in this study concentrate on preparation of proper reference materials for elemental mapping, quantification by µ-PIXE and LA-ICP-MS and comparison of results for species from different origin, with different diet, sex and age.

 

 

Analytical Methods

  • Field emission electron microscopy (FE-SEM)
  • Electron beam micro analysis (ESMA)
    Energydispersive X-ray spectroscopy (EDX)
  • Micro X-ray fluorescence spectroscopy (µXRF)
  • Particle-/ Proton induced X-ray emission spectroscopy (PIXE)
  • Laser ablation coupled to inductively coupled plasma mass spectrometry (LA-ICP-MS)

Publications

  • G. C. Schwartze, Mikrobereichsanalytik an marinen Biomineralisationsprodukten. Copepoden des Südpolarmeeres und der Nordsee, Diplomarbeit (2010), GRIN Verlag GmbH, München, 2011, ISBN 978-3640854387
  • K. Bechstein, J. Michels, J. Vogt, G. C. Schwartze, C. Vogt, Position-resolved determination of trace elements in mandibular gnathobases of the Antarctic copepod Calanoides acutus using a multimethod approach, Anal. Bioanal. Chem., 399: 501-508, 2011, DOI:10.1007/s00216-010-4373-5

Cooperation partners

  • Dr. Jan Michels, Zoologisches Institut, Christian-Albrechts-Universität zu Kiel
  • Stiftung Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven