Direct observation of unstained biological specimens in water by the frequency transmission electric-field method using SEM.

Scanning electron microscopy (SEM) is a powerful tool for the direct visualization of biological specimens at nanometre-scale resolution. However, images of unstained specimens in water using an atmospheric holder exhibit very poor contrast and heavy radiation damage. Here, we present a new form of...

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Main Author: Toshihiko Ogura
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2014-01-01
Series:PLoS ONE
Online Access:http://europepmc.org/articles/PMC3961424?pdf=render
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author Toshihiko Ogura
author_facet Toshihiko Ogura
author_sort Toshihiko Ogura
collection DOAJ
description Scanning electron microscopy (SEM) is a powerful tool for the direct visualization of biological specimens at nanometre-scale resolution. However, images of unstained specimens in water using an atmospheric holder exhibit very poor contrast and heavy radiation damage. Here, we present a new form of microscopy, the frequency transmission electric-field (FTE) method using SEM, that offers low radiation damage and high-contrast observation of unstained biological samples in water. The wet biological specimens are enclosed in two silicon nitride (SiN) films. The metal-coated SiN film is irradiated using a focused modulation electron beam (EB) at a low-accelerating voltage. A measurement terminal under the sample holder detects the electric-field frequency signal, which contains structural information relating to the biological specimens. Our results in very little radiation damage to the sample, and the observation image is similar to the transmission image, depending on the sample volume. Our developed method can easily be utilized for the observation of various biological specimens in water.
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spelling doaj.art-0b6086f3ec9a44c6935e7d64594a43412022-12-21T20:45:14ZengPublic Library of Science (PLoS)PLoS ONE1932-62032014-01-0193e9278010.1371/journal.pone.0092780Direct observation of unstained biological specimens in water by the frequency transmission electric-field method using SEM.Toshihiko OguraScanning electron microscopy (SEM) is a powerful tool for the direct visualization of biological specimens at nanometre-scale resolution. However, images of unstained specimens in water using an atmospheric holder exhibit very poor contrast and heavy radiation damage. Here, we present a new form of microscopy, the frequency transmission electric-field (FTE) method using SEM, that offers low radiation damage and high-contrast observation of unstained biological samples in water. The wet biological specimens are enclosed in two silicon nitride (SiN) films. The metal-coated SiN film is irradiated using a focused modulation electron beam (EB) at a low-accelerating voltage. A measurement terminal under the sample holder detects the electric-field frequency signal, which contains structural information relating to the biological specimens. Our results in very little radiation damage to the sample, and the observation image is similar to the transmission image, depending on the sample volume. Our developed method can easily be utilized for the observation of various biological specimens in water.http://europepmc.org/articles/PMC3961424?pdf=render
spellingShingle Toshihiko Ogura
Direct observation of unstained biological specimens in water by the frequency transmission electric-field method using SEM.
PLoS ONE
title Direct observation of unstained biological specimens in water by the frequency transmission electric-field method using SEM.
title_full Direct observation of unstained biological specimens in water by the frequency transmission electric-field method using SEM.
title_fullStr Direct observation of unstained biological specimens in water by the frequency transmission electric-field method using SEM.
title_full_unstemmed Direct observation of unstained biological specimens in water by the frequency transmission electric-field method using SEM.
title_short Direct observation of unstained biological specimens in water by the frequency transmission electric-field method using SEM.
title_sort direct observation of unstained biological specimens in water by the frequency transmission electric field method using sem
url http://europepmc.org/articles/PMC3961424?pdf=render
work_keys_str_mv AT toshihikoogura directobservationofunstainedbiologicalspecimensinwaterbythefrequencytransmissionelectricfieldmethodusingsem