蜘蛛大壶状腺丝的反复拉伸力学行为和性能

Repetitive Stretching Tensile Behavior and Properties of Spider Major Ampullate Gland Silk

利用电子万能试验机与激光拉曼光谱仪对蜘蛛大壶状腺丝的反复拉伸力学行为及其拉伸后蛋白二级结构的变化进行测试研究。结果表明,大壶状腺丝具有优良的反复拉伸特性,且越拉越硬,但其屈服强度基本保持不变;前后两组分别定伸长间隔15~25 s和5 min拉过屈服点甚至拉伸至加强区的力学行为曲线均重叠良好;前后两组拉伸长时间(≥23 min)间隔后,只需一次拉伸就能不受拉伸历史的影响重现之前的力学行为,表现出类似橡胶的粘弹性力学行为特征;大壶状腺丝被反复拉伸时无规则卷曲之间的氢键断裂,停止拉伸卸载松弛后间隔时间的延长使部分结构恢复,同时形成β-转角或β-弯曲以及PGⅡβ-折叠的新结构,经多次反复拉伸后原有的β-折叠结构逐渐被破坏,断裂时被全部破坏。本研究结果对人们进行新型功能纤维材料的仿生设计具有重要的指导意义。

In order to analyze and explore the changes of deformation, mechanical behavior and structure of spider major ampullate gland silk(abbr: Mas) during repetitive stretching and their relationship,the mechanical behavior of spider Mas and the changes of protein secondary structure after repetitive stretching were tested and investigated through the design of different combinations of loading elongation and the interval relaxation between the two stretching via electronic universal testing machine and laser Raman spectrometer. The results show that spider Mas presents excellent repetitive stretching characteristics with the gradual increase of the initial modulus but the a marginal variation in yield stress;When two groups of spider Mas fibers were stretched in the condition of gradual increase of the set stretching length and the set time intervals as 15~25 s and 5 min respectively, as a result, the acquired tensile curves of the two groups overlapped fairly well, even for the samples were stretched over the yield point, or even over the yield zone and into the strengthening zone as well;It reveals that in case the stretching test of the above two groups of samples has been interrupted for a long time interval of ≥23 min in between two stretching tests,the mechanical behavior of samples may be reproduced as soon as only one stretch again independent from the previous loading history. In other word, the above findings show that the mechanical behavior of spider Mas is similar to those of rubber’s viscoelasticity. The results of Raman spectra showed that with the increase of the number of repetitive stretching and the set stretching length, the hydrogen bond between the random coils was broken. The interval after stretching seems to allow some structures to recover and contribute to the formation of the new β-turn or β-bend and PGⅡ β-sheet structure, After repetitive stretching for many times, the primitive β-sheet structure will be gradually destroyed, and almost all of it will be destroyed when Mas breaks. These findings may be helpful to guide the biomimetic design of novel fiber materials.