Page:Nanostructural Organization of Naturally Occurring Composites Part II.pdf/1

 Hindawi Publishing Corporation Journal of Nanomaterials Volume 2008, Article ID 670235, 8 pages doi:10.1155/2008/670235

Research Article =Nanostructural Organization of Naturally Occurring Composites—Part II: Silica-Chitin-Based Biocomposites=

Hermann Ehrlich,1 Dorte Janussen,2 Paul Simon,3 Vasily V. Bazhenov,4 Nikolay P. Shapkin,4 Christiane Erler,1 Michael Mertig,1 René Born,1 Sascha Heinemann,1 Thomas Hanke,1 Hartmut Worch,1 and John N. Vournakis5

1 Max Bergmann Center of Biomaterials and Institute of Materials Science, Dresden University of Technology, 01069 Dresden, Germany 2 Forschungsinstitut und Naturmuseum Senckenberg, Senckenberganlage 25, 60325 Frankfurt am Main, Germany 3 Max Planck Institute of Chemical Physics of Solids, 01187 Dresden, Germany 4 Institute of Chemistry and Applied Ecology, Far Eastern National University, 690650 Vladivostok, Russia 5 Marine Polymer Technologies, Inc., Danvers, MA 01923, USA

Correspondence should be addressed to Hermann Ehrlich, hermann.ehrlich@tu-dresden.de

Received 2 November 2007; Accepted 26 February 2008

Recommended by Donglu Shi

Investigations of the micro- and nanostructures and chemical composition of the sponge skeletons as examples for natural structural biocomposites are of fundamental scientific relevance. Recently, we show that some demosponges (Verongula gigantea, Aplysina sp.) and glass sponges (Farrea occa, Euplectella aspergillum) possess chitin as a component of their skeletons. The main practical approach we used for chitin isolation was based on alkali treatment of corresponding external layers of spicules sponge material with the aim of obtaining alkali-resistant compounds for detailed analysis. Here, we present a detailed study of the structural and physicochemical properties of spicules of the glass sponge Rossella fibulata. The structural similarity of chitin derived from this sponge to invertebrate alpha chitin has been confirmed by us unambiguously using physicochemical and biochemical methods. This is the first report of a silica-chitin composite biomaterial found in Rossella species. Finally, the present work includes a discussion related to strategies for the practical application of silica-chitin-based composites as biomaterials.

Copyright © 2008 Hermann Ehrlich et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

1. INTRODUCTION
This is the second paper on naturally occurring silica-based biocomposites of sponges origin. The initial paper [1] studied the presence of fibrillar collagen as a component of glassy anchoring spicule of Monorphaphis sp. glass sponge. Biocomposites of marine origin including sponge skeletal formations are a constant source of inspiration for finding solutions to a variety of technical challenges in bionics, architecture, optics, engineering, as well as materials science and biomedicine (reviewed in [2, 3]). The biomimetic potential of marine sponges seems to be a goldmine to material scientists. Several main aspects relating to sponges as biomaterials and biocomposites are recently described as follows [3]: (i) hexactinellid spicules as natural glass-based composites with specific mechanical properties [4, 5]; (ii) skeleton of Euplectella sp. (Hexactinellida) as a hierarchical natural structural material of remarkable design [6, 7]; (iii) basal spicules of Hexactinellida as biological glass fibers with specific optical properties [8–10]; (iv) silicatein-based biocatalitic formation of nanocomposite materials (reviewed in [11]); (v) biomimetically inspired hybrid materials based on silicified sponge collagen [12–14]. In case of hexactinellid spicules, it is reported that they are highly flexible and tough, possibly not only because of their layered structure and the hydrated nature of the silica as suggested earlier [15], but of the presence of collagen [16] or chitin [17]. According to paleontological and molecular data, the sponge class Hexactinellida may be the oldest