Nanostructural Organization of Naturally Occurring Composites—Part I: Silica‐Collagen‐Based Biocomposites

Hermann Ehrlich,René Born,Sascha Heinemann,Vasily V Bazhenov,Christiane Heinemann,Paul Simon,Hartmut Worch,Nikolay P Shapkin,Konstantin R Tabachnick,Thomas Hanke

doi:10.1155/2008/623838

Abstract

Glass sponges, as examples of natural biocomposites, inspire investigations aiming at both a better understanding of biomineralization mechanisms and novel developments in the synthesis of nanostructured biomimetic materials. Different representatives of marine glass sponges of the class Hexactinellida (Porifera) are remarkable because of their highly flexible basal anchoring spicules. Therefore, investigations of the biochemical compositions and the micro‐ and nanostructure of the spicules as examples of naturally structured biomaterials are of fundamental scientific relevance. Here we present a detailed study of the structural and biochemical properties of the basal spicules of the marine glass sponge Monorhaphis chuni. The results show unambiguously that in this glass sponge a fibrillar protein of collagenous nature is the template for the silica mineralization in all silica‐containing structural layers of the spicule. The structural similarity and homology of collagens derived from M. chuni spicules to other sponge and vertebrate collagens have been confirmed by us using FTIR, amino acid analysis and mass spectrometric sequencing techniques. We suggest that nanomorphology of silica formed on proteinous structures could be determined as an example of biodirected epitaxial nanodistribution of amorphous silica phase on oriented fibrillar collagen templates. Finally, the present work includes a discussion relating to silica‐collagen‐based hybrid materials for practical applications as biomaterials.

Highlights

Glass sponges (Hexactinellida: Porifera) provide an abundant source of unusual skeleton structures, which could be defined as natural silica-based nanostructured composite materials
We provide a detailed study confirming our hypothesis that the nanofibrillar organic matrix of collagenous nature within the giant spicules of M. chuni is responsible for their extraordinary mechanical properties
The nanolocalization of the proteinaceous component of the glass sponge spicules was not investigated in detail because of lack of a demineralization method which preserved the organic matrix during desilicification

Summary

Introduction

Glass sponges (Hexactinellida: Porifera) provide an abundant source of unusual skeleton structures, which could be defined as natural silica-based nanostructured composite materials They are intriguing research objects because of the hierarchical organization of their spicules from the nanoscale to the macroscale [1,2,3]. First observations reported by Levi et al [4] on silica-based spicules of a Monorhaphis sponge generated great interest because of their combination of properties, namely, toughness combined with stiffness, and resilience. This sponge species synthesizes the largest biosilica structures on earth [5]. Smallangle X-ray scattering revealed the presence of nanospheres with a diameter of only 2.8 nm as the basic unit of silica

Objectives

Results

Conclusion