title: X-ray diffraction study of nanocrystalline and amorphous structure within major and minor ampullate dragline spider silks.
abstract: Synchrotron X-ray micro-diffraction experiments were carried out onNephila clavipes(NC) andArgiope aurantia(AA) major (MA) and minor ampullate (MiA) fibers that make up dragline spider silk. The diffraction patterns show a semi-crystalline structure with β-poly(l-alanine) nanocrystallites embedded in a partially oriented amorphous matrix. A superlattice reflection 'S' diffraction ring is observed, which corresponds to a crystalline component larger in size and is poorly oriented, when compared to the β-poly(l-alanine) nanocrystallites that are commonly observed in dragline spider silks. Crystallite size, crystallinity and orientation about the fiber axis have been determined from the wide-angle X-ray diffraction (WAXD) patterns. In both NC and AA, the MiA silks are found to be more highly crystalline, when compared with the corresponding MA silks. Detailed analysis on the amorphous matrix shows considerable differences in the degree of order of the oriented amorphous component between the different silks studied and may play a crucial role in determining the mechanical properties of the silks.
authors.affiliation: Department of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, AZ, 85287-1604, USA.
authors.forename: Sujatha
authors.initials: S
authors.lastname: Sampath
authors.forename: Thomas
authors.initials: T
authors.lastname: Isdebski
authors.forename: Janelle E
authors.initials: JE
authors.lastname: Jenkins
authors.forename: Joel V
authors.initials: JV
authors.lastname: Ayon
authors.forename: Robert W
authors.initials: RW
authors.lastname: Henning
authors.forename: Joseph P R O
authors.initials: JP
authors.lastname: Orgel
authors.forename: Olga
authors.initials: O
authors.lastname: Antipoa
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Yarger