Hierarchical Architecture of Sponge Spicules: Bio-inspired assembly of multifunctional structures by biocatalytically active and structure-guiding proteins

点击翻译按钮获取中文摘要

The hierarchically structured skeletons of the siliceous sponges, the Demospongia and the Hexactinellida (glass sponges), and of the calcareous sponges, the Calcarea, with their exceptional opto-mechanical properties have turned out to be excellent models for biomimetic approaches. The biosilica of the siliceous sponges is formed by a unique group of enzymes, the silicateins, that turned out to show both biocatalytic and structure-guiding/forming activity. The species-specific 3D structure of their skeleton is controlled both on gene level, by a sequential gene expression of silicatein and silicatein interacting proteins, and by the specific interaction and assembly of these proteins to filamentous structures, as well as by cellular processes. In the first funding period, fundamental insights have been gained in the inorganic-organic hybrid structure of the spicules and in the mechanism of biosilica formation which was unequivocally proven to occur enzymatically. In the second funding period, new silicatein interactors (silintaphins) have been discovered and functionally characterized, allowing an understanding of the regulation not only of silicatein assembly/activity but also of the formation of the extracellular cylinder-like organic scaffold guiding the longitudinal and appositional growth of the spicules. Moreover, the processes of syneresis and hardening/ageing of the enzymatically formed soft biosilica to solid silica rods have been demonstrated for the first time, opening new avenues for biomimetic/bio-inspired applications of sponge biosilica. In the third period, we will use these tools for the generation of hierarchically structured and multifunctional nanomaterials, applying bio-inspired molecular switches and mimicking precision biosilica molding processes realized in sponges in nature. Among others, the effect of silicatein on the formation of CaCO3/silicatein hybrid fibers (synthetic spicules) shall be studied. The close collaboration between groups from inorganic chemistry and molecular biology shall allow it to exploit the self-assembly, structure-directing and biocatalytic capabilities of the sponge proteins involved in biomineralization, along with nanoparticles of calcium carbonate and metal oxides, for the generation of biomimetic nanostructured materials with new property combinations, whose mechanical and optical properties shall be examined as a function of their composition.