Aspects of the Morphology of Dragline Silk of <i>Nephila clavipes</i>

Samples of golden orb-weaver dragline silk were observed to undergo large tensile and compressive deformations (~40%) without evidence of fracture in tension or kinking in compression. The absence of kinking is consistent with the absence of a fibrillar structure within the fiber such as those microfibrils observed in high performance polymer fibers. Therefore, the lack of failure prompted an examination of the morphology of the silk. Low voltage high resolution scanning electron microscopy (LVHRSEM) and atomic force microscopy (AFM) were used to examine as-spun, fractured and abraded fibers. The images yielded a rich variety of features. These were examined by the original height profiles of the AFM images and by Fourier transforms of the profiles. A broad range of dimensions of features is present. These features occur on the surface of as-spun silk as well as on the surfaces exposed through abrasion and liquid nitrogen fracture.