Characterization of natural and biomimetic spider silk fibers

Spider silk produced by orb-weaving spiders reveals fascinating mechanical properties, in particular, its unique combination of high tensile strength and elasticity, distinguishing it from most other natural or man-made fibers. Here, mechanical characteristics of dragline silk fibers of Araneus diadematus were determined after forcibly silking at varying reeling speeds, humidity, as well as in the presence of water. In comparison, fibers of a recombinant silk protein (eADF3(AQ24NR3)) using solely aqueous solutions was produced. Mechanical properties of these biotech fibers were in the range of other artificial silk fibers made from proteins with comparable molecular weight. Structural investigations by Fourier-transform infrared spectroscopy revealed that the ß-sheet content of the biotech fibers is lower and the ß-sheets are less oriented in comparison to native dragline silks. The results suggest that pulling fibers from aqueous solutions in combination with postspin techniques will help to produce artificial silk fibers with mechanical properties for distinct technical or medical applications.