Hierarchies in the structural organization of spider silk-a quantitative model

The unsurpassed mechanical properties of major ampullate spider silk are quantitatively explained by a hierarchical model of its structural organization. Based on combined time-resolved mechanical and Fourier-transform infrared measurements, we show that the core of native silk fibers is strongly prestressed. The prestress is released during wetting, allowing the fibers to shrink, changing permanently the mechanical properties. Prestress is, therefore, the controlling parameter of silk properties.