竹纤维柱辅助断裂法在制备水凝胶冷冻扫描电子显微镜样品中的应用

Novel Fine Bamboo Pillar Assisted Freeze-Fracture Method for Hydrogel Sample Preparation of Cryogenic Scanning Electron Microscope

  • 摘要: 冷冻扫描电子显微镜(cryogenic scanning electron microscopy, cryo-SEM)是观察样品含水状态下真实微观形貌不可替代的分析手段,其中样品的冷冻断裂步骤是获得理想测试结果的关键步骤之一. 水凝胶样品由于含水量丰富,质地柔软难以成形,在利用常规冷刀断裂方法进行冷冻断裂时,存在难以获得理想断裂面、断裂效率低等问题. 因此创新性地提出了一种竹纤维柱辅助断裂方法,在样品冷冻固定前,将细小的竹纤维柱插入水凝胶样品顶端. 冷冻断裂时,冷刀不直接作用在样品上,而是通过撬动与样品相连的竹纤维柱,实现样品与纤维柱接触部位的冷冻断裂. 可轻松获得大范围可观测断裂面,且样品应力损伤小,无表面样品碎屑干扰,还可实现多个样品一次性同时断裂,是一种高质、高效的水凝胶冷冻断裂方法.

     

    Abstract: Cryogenic scanning electron microscopy (cryo-SEM) is an irreplaceable approach to investigate the real surface morphology and microstructure of hydrated samples. The freeze-fracture of samples is one of the most important pretreatments to obtain ideal results. Due to the high content of water, hydrogel samples are very soft and difficult to handle when performing cryo-SEM sample preparation. During the freeze-fracture procedure using conventional fracture method with cold knife, it is difficult to obtain high-quality fractured surface and the efficiency is rather low. Therefore, a novel method of the freeze-fracture for hydrogel samples by employing fine bamboo pillars for assistance has been proposed. Before the cryo-fixation of samples, fine bamboo pillars were inserted at the top of the hydrogel samples. During freeze-fracture process, the cold knife would pry the fine bamboo pillars away and make a cleavage of hydrogel sample instead of hitting the sample directly to achieve freeze-fracture in the area of contact between the sample and the fine bamboo pillar. By the method, a large area of fractured surface could be revealed for SEM investigation. The damage to sample caused by stress was reduced, and a clear sample surface free of debris was provided. Meanwhile, multiple samples were fractured simultaneously at one time, which significantly enhanced the efficiency of freeze-fracture.

     

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