Research Article

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

Figure 5

proposed model of micro- and nanostructural organisation of the basal spicule of M. chuni with respect to the organic matrix. (a) Collagen nets, surrounding the spicules, showed a tight mat of nanofibrils. Schematic view (b) shows a collagenous fibrillar matrix which could function as a glue between concentric layers. Image (c) represents the region of the axial canal and axial filament. The axial canal of M. chuni possesses a characteristic quadratic opening (c) and contains oriented bundles of unsilicified collagenous nanofibrils. The base material of the walls of the axial canal and concentric layers distributed above it consists of silicified collagen fibrils with a twisted plywood orientation. This kind of fibrillar architecture could be responsible for the remarkable micromechanical properties of the spicule as a biocomposite.
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