Comparison of the Spinning of Selachian Egg Case Ply Sheets and Orb Web Spider Dragline Filaments
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- 作者：David P. Knight and Fritz Vollrath
- 刊名：Biomacromolecules
- 出版年：2001
- 出版时间：June 2001
- 年：2001
- 卷：2
- 期：2
- 页码：323 - 334
- 全文大小：1268K
- 年卷期：v.2,no.2(June 2001)
- ISSN：1526-4602
文摘
Liquid crystal spinning appears to be widespread in the animal kingdom, utilizing protein dopes to givematerials with a range of different secondary structures including 
fchars/beta2.gif" BORDER=0 ALIGN="middle">-pleat, fchars/alpha.gif" BORDER=0>-helix and collagen-fold. Herewe seek to identify the essential design features used in natural liquid crystal spinning by comparing thespinning of two very different materials: the egg case wall of Selachians (dogfish, rays, and their allies)and the dragline silk of orb web spiders. The fish extrudes a "sea and island" composite in which theislands consist of flat ribbons of carefully orientated collagen and the sea, small quantities of an amorphousmatrix. Dragline silk filaments are largely constructed from spidroin, a fchars/beta2.gif" BORDER=0 ALIGN="middle"> protein and have a skin and corestructure together with two to three coats. The essential design features common to both systems appear tobe the following: (i) intracellular co-storage of a hexagonal columnar liquid crystalline component and aperoxidase within the same secretory vesicles; (ii) luminal storage of a highly concentrated liquid crystallinedope; (iii) use of a dope containing immiscible droplets; (iv) hyperbolic extrusion dies; (v) control of pHand water content of the dope; (vi) preorientation of dope molecules before assembly into fibrils; (vii)combination of extrusion die, treatment/coating bath, and solvent recovery plant within a singlemicrominiaturized device; (viii) slow natural spinning rates. The most important difference is that spidersproduce a tough material by unfolding and hydrogen-bonding their silk dope molecules while Selachianfish do it by covalently cross-linking the molecules without unfolding them.
fchars/beta2.gif" BORDER=0 ALIGN="middle">-pleat, fchars/alpha.gif" BORDER=0>-helix and collagen-fold. Herewe seek to identify the essential design features used in natural liquid crystal spinning by comparing thespinning of two very different materials: the egg case wall of Selachians (dogfish, rays, and their allies)and the dragline silk of orb web spiders. The fish extrudes a "sea and island" composite in which theislands consist of flat ribbons of carefully orientated collagen and the sea, small quantities of an amorphousmatrix. Dragline silk filaments are largely constructed from spidroin, a fchars/beta2.gif" BORDER=0 ALIGN="middle"> protein and have a skin and corestructure together with two to three coats. The essential design features common to both systems appear tobe the following: (i) intracellular co-storage of a hexagonal columnar liquid crystalline component and aperoxidase within the same secretory vesicles; (ii) luminal storage of a highly concentrated liquid crystallinedope; (iii) use of a dope containing immiscible droplets; (iv) hyperbolic extrusion dies; (v) control of pHand water content of the dope; (vi) preorientation of dope molecules before assembly into fibrils; (vii)combination of extrusion die, treatment/coating bath, and solvent recovery plant within a singlemicrominiaturized device; (viii) slow natural spinning rates. The most important difference is that spidersproduce a tough material by unfolding and hydrogen-bonding their silk dope molecules while Selachianfish do it by covalently cross-linking the molecules without unfolding them.