Sponges as natural composites: from biomimetic potential to development of new biomaterials

Abstract

Investigations of the compositions and the microstructures of the sponge skeletons as examples for natural structural biomaterials are of fundamental scientific relevance. Recently, we show that some demosponges (Verongula gigantea, Aplysina sp.) and glass sponges (Farrea occa) possess chitin as a component of their skeletons. The main practical approach we used for chitin isolation was based on alkali treatment of corresponding exoskeletal sponge material with the aim of obtaining alkaliresistant compounds for detailed analysis. Here, we present a detailed study of the structural and physico-chemical properties of skeletal fragments of the glass sponge Euplectella aspergillum. The structural similarity of chitin derived from this sponge to invertebrate alpha-chitin has been confirmed by us unambiguously using physico-chemical and biochemical methods. This is the first report of a silica-chitin composite biomaterial found in Euplectella species. Finally, the present work includes a discussion relating to strategies for the practical application of sponges as biomaterials. A comprehensive understanding of collagen- and chitin-based sponge skeletons with respect to chemical composition and structure may prove to be a novel model for biomimetic synthesis of three-dimensional collagen- and chitin-based composites with specific mechanical, optical and bioactive properties for applications in different modern technologies, including materials science and biomedicine.