ORIGINAL ARTICLE Oleg Prymak Æ Henry Tiemann Æ Ilka So¨tje Julia C. Marxen Æ Arndt Klocke Æ Ba¨rbel Kahl-Nieke Felix Beckmann Æ Tilman Donath Æ Matthias Epple Application of synchrotron-radiation-based computer microtomography (SRlCT) to selected biominerals: embryonic snails, statoliths of medusae, and human teeth Received: 14 March 2005 / Accepted: 16 August 2005 / Published online: 27 September 2005 Ó SBIC 2005 Abstract Synchrotron-radiation-based computer micro- tomography (SRlCT) was applied to three biominera- lised objects First, embryonic snails of the freshwater snail Biomphalaria glabrata, second, rhopalia (complex sense organs) of the medusa Aurelia aurita, and third, human teeth. The high absorption contrast between the soft tissue and mineralised tissues, i.e. the shell in the first case (consisting of calcium carbonate) and the statoliths in the second case (consisting of calcium sulphate hemihydrate), makes this method ideal for the study of biomineralised tissues. The objects can be non-destructively studied on a micrometre scale, and quantitative parameters like the thickness of a forming a snail shell or statolith crystal sizes can be obtained on a length scale of 1–2 lm. Using SRlCT, the dentin– enamel border can be clearly identified in X-ray dense teeth. Keywords Synchrotron radiation Microtomography Æ Biomineralisation Bioinorganic chemistry Introduction Biomineralisation denotes the utilisation of inorganic minerals by living organisms [1–4]. Typical examples are exoskeletons of molluscs (like shells from snails or mussels), teeth and bone, statoliths, spines, and min- eralised plant leaves. The underlying processes are still poorly understood, despite significant efforts from the sides of both materials science and biology. However, it is accepted that a delicate interplay between the growing inorganic crystal and the underlying organic matrix (consisting of biomacromolecules like proteins and sugars) is the main parameter in this process [5–7]. This occurs on the molecular length scale, and finally min- eralised tissues of the order of millimetres and centime- tres are formed, like bone and teeth that contain calcium phosphate [8, 9]. The three-dimensional structure of such biominera- lised organs on the intermediate length scale (i.e. tens and hundreds of a micrometre) lies between these two extremes of, say, ions and molecules and, for example, the final snail shell, tooth, or bone. In order to correlate these two length scales, it is therefore of interest to study mineralised tissues on a micrometre scale. Synchrotron-radiation-based computer microtomog- raphy (SRlCT) [10] offers a convenient way to distin- guish between mineralised tissues (containing the mineral) and the surrounding organic tissue because the absorption of X-rays is strongly different for these two phases [11, 12]. Moreover, tissues can be studied without the need for destruction (as it is always necessary for microscopic and histological techniques), and virtual cuts can be performed once a three-dimensional dataset has been obtained. For instance, Nuzzo et al. [13] analysed the three- dimensional structure and mineralisation of human bone, and Martin-Badosa et al. [14] compared histo- morphometric results with quantitative SRlCT data on mouse bone. Stock et al. [15, 16] studied bone formation O. Prymak Æ M. Epple (&) Institute for Inorganic Chemistry, University Duisburg–Essen, Universita¨tsstrasse 5-7, 45117 Essen, Germany E-mail: matthias.epple@uni-essen.de H. Tiemann Æ I. So¨tje Æ J. C. Marxen Biocenter Grindel, University of Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany A. Klocke Æ B. Kahl-Nieke Department of Orthodontics, University Hospital Hamburg–Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany F. Beckmann Æ T. Donath GKSS Research Center Geesthacht, Institute for Materials Research, Max-Planck-Strasse 1, 21502 Geesthacht, Germany J Biol Inorg Chem (2005) 10: 688–695 DOI 10.1007/s00775-005-0023-3