Non-destructive observation of intact bacteria and viruses in water by the highly sensitive frequency transmission electric-field method based on SEM
Non-destructive observation of intact bacteria and viruses in water by the highly sensitive frequency transmission electric-field method based on SEM
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DOI：
10.1016/j.bbrc.2014.07.062
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发表时间：
2014-08-08
影响因子：
3.1
通讯作者：
Ogura, Toshihiko
中科院分区：
文献类型：
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作者：
Ogura, Toshihiko
通过扫描电子显微镜 (SEM) 对生物样本进行高分辨率结构分析具有多种优势。到目前为止，湿细菌标本都是使用大气样品架进行检查的。然而，使用这些支架在水中未染色样本的图像表现出非常差的对比度和严重的辐射损伤。最近，我们开发了频率传输电场（FTE）方法，该方法有助于在水中对生物标本进行扫描电镜观察而不会造成辐射损伤。然而，信号检测系统的灵敏度较低。因此，需要高电子束电流才能产生清晰的图像，从而降低空间分辨率并引起样品的热损伤。这里针对FTE方法开发了高灵敏度检测系统，将输出信号幅度增强了数百倍。当电压施加到氮化硅薄膜上的金属层时，检测信号大大增强。这种增强减少了 EB 电流并提高了空间分辨率和信噪比。高灵敏度 FTE 系统的空间分辨率为 41 nm，大大高于以前的 FTE 系统。新的 FTE 系统可轻松用于检查水中各种未染色的生物样本，例如活细菌和病毒。 (C) 2014 年作者。由爱思唯尔公司出版
The high-resolution structural analysis of biological specimens by scanning electron microscopy (SEM) presents several advantages. Until now, wet bacterial specimens have been examined using atmospheric sample holders. However, images of unstained specimens in water using these holders exhibit very poor contrast and heavy radiation damage. Recently, we developed the frequency transmission electric-field (FTE) method, which facilitates the SEM observation of biological specimens in water without radiation damage. However, the signal detection system presents low sensitivity. Therefore, a high EB current is required to generate clear images, and thus reducing spatial resolution and inducing thermal damage to the samples. Here a high-sensitivity detection system is developed for the FTE method, which enhances the output signal amplitude by hundredfold. The detection signal was highly enhanced when voltage was applied to the metal layer on silicon nitride thin film. This enhancement reduced the EB current and improved the spatial resolution as well as the signal-to-noise ratio. The spatial resolution of a high-sensitive FTE system is 41 nm, which is considerably higher than previous FTE system. New FTE system can easily be utilised to examine various unstained biological specimens in water, such as living bacteria and viruses. (C) 2014 The Author. Published by Elsevier Inc.