Hierarchical spidroin micellar nanoparticles as the fundamental precursors of spider silks
Hierarchical spidroin micellar nanoparticles as the fundamental precursors of spider silks
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DOI：
10.1073/pnas.1810203115
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发表时间：
2018-11-06
影响因子：
11.1
通讯作者：
Holland, Gregory P.
中科院分区：
文献类型：
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作者：
Parent, Lucas R.;Onofrei, David;Holland, Gregory P.
蜘蛛和昆虫产生的许多天然丝是独特的材料，具有特殊的韧性和拉伸强度，同时具有轻质和可生物降解的特性，这些特性是目前合成材料无法比拟的。人们尝试了无数种方法从重组蜘蛛丝蛛丝制备人造丝，但每种方法都未能实现天然材料的有利特性。这是因为对体内蛛丝蛋白-纤维纺丝过程的不完全理解，特别是因为缺乏对前体纺丝原液溶液中蛛丝蛋白纳米结构的真实形态性质以及这些纳米结构转化为微米级丝纤维的机制的了解。在这里，我们确定的物理形式的天然蛛丝蛋白前体纳米结构存储在蜘蛛腺，种子形成他们的丝，并揭示了基本的结构转换过程中发生的挤压途中纤维形成的初始阶段。利用溶液相扩散核磁共振和低温透射电子显微镜的组合（cryo-TEM），我们揭示了直接的证据，即浓缩的蛛丝蛋白作为复杂的、分级的纳米组装体（类似于300 nm直径）存储在黑寡妇蜘蛛的丝腺中，所述纳米组装体由胶束子域、子结构组成，所述子结构本身参与响应于剪切而发生的初始纳米级转变。我们发现，已建立的胶束理论的丝纤维前体存储是不完整的，并在纺丝过程中液晶组织的第一步涉及的纳米级的分级胶束子域的fietization。
Many natural silks produced by spiders and insects are unique materials in their exceptional toughness and tensile strength, while being lightweight and biodegradable-properties that are currently unparalleled in synthetic materials. Myriad approaches have been attempted to prepare artificial silks from recombinant spider silk spidroins but have each failed to achieve the advantageous properties of the natural material. This is because of an incomplete understanding of the in vivo spidroin-to-fiber spinning process and, particularly, because of a lack of knowledge of the true morphological nature of spidroin nanostructures in the precursor dope solution and the mechanisms by which these nanostructures transform into micrometer-scale silk fibers. Herein we determine the physical form of the natural spidroin precursor nanostructures stored within spider glands that seed the formation of their silks and reveal the fundamental structural transformations that occur during the initial stages of extrusion en route to fiber formation. Using a combination of solution phase diffusion NMR and cryogenic transmission electron microscopy (cryo-TEM), we reveal direct evidence that the concentrated spidroin proteins are stored in the silk glands of black widow spiders as complex, hierarchical nanoassemblies (similar to 300 nm diameter) that are composed of micellar subdomains, substructures that themselves are engaged in the initial nanoscale transformations that occur in response to shear. We find that the established micelle theory of silk fiber precursor storage is incomplete and that the first steps toward liquid crystalline organization during silk spinning involve the fibrillization of nanoscale hierarchical micelle subdomains.