The mechanical performance of synthetic can be strongly enhanced by the implementation of structural design principles of biomaterials. The highly flexible giant spicule of sponges is one fascinating example of bio-ceramic rods that exhibit superior mechanical properties under bending stress. The spicule’s hierarchical organization in the form of cylindrically arranged inorganic lamellas connected by an organic component is unique, and ensures a high mechanical flexibility. Mimicking the spicule’s microstructure is a challenging task, which requires an intricate assembly of the nanostructured building blocks across several hierarchical levels.
Here, we report novel preparation methods to fabricate scrolls that mimic the cylindrically shaped lamellas of the sponge spicule. One approach to the scrolls involves the controlled removal of a solid-supported thin film with a razor blade. As an alternative, a thin layer with a different drying gradient is deposited on top of the thin film to induce self-scrolling. In this context, V2O5 nanofiber-based thin films are of particular interest due to their hierarchical arranged, self-assembled microstructure, which imparts a high mechanical flexibility as a perquisite for scrolling up the films into spicule-like rods. Scanning electron microscopy (SEM) revealed a uniform, spiral-like structure of the scrolls, with a length of several millimeter, and a diameter in the micrometer range. Investigation of the mechanical properties of the films by 3-point bending test revealed similar fracture behavior like for the sponge spicule.
The novel approaches to 3D spicule-like scrolls based on 2D thin films open up novel perspectives for the fabrication of nanostructured, biomimetic and multifunctional systems.
 Z. Burghard, A. Leineweber, P. A. van Aken, T. Dufaux, M. Burghard and J. Bill, Advanced Materials, 2013, 25, 2468.