Direct observation of unstained wet biological samples by scanning-electron generation X-ray microscopy

Journal Article · Fri Jan 01 00:00:00 EST 2010 · Biochemical and Biophysical Research Communications

DOI:https://doi.org/10.1016/J.BBRC.2009.11.031· OSTI ID:22199961

Ogura, Toshihiko ^[1]

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1. Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

Analytical tools of nanometre-scale resolution are indispensable in the fields of biology, physics and chemistry. One suitable tool, the soft X-ray microscope, provides high spatial resolution of visible light for wet specimens. For biological specimens, X-rays of water-window wavelength between carbon (284 eV; 4.3 nm) and oxygen (540 eV; 2.3 nm) absorption edges provide high-contrast imaging of biological samples in water. Among types of X-ray microscope, the transmission X-ray microscope using a synchrotron radiation source with diffractive zone plates offers the highest spatial resolution, approaching 15-10 nm. However, even higher resolution is required to measure proteins and protein complexes in biological specimens; therefore, a new type of X-ray microscope with higher resolution that uses a simple light source is desirable. Here we report a novel scanning-electron generation X-ray microscope (SGXM) that demonstrates direct imaging of unstained wet biological specimens. We deposited wet yeasts in the space between two silicon nitride (Si{sub 3}N{sub 4}) films. A scanning electron beam of accelerating voltage 5 keV and current 1.6 nA irradiates the titanium (Ti)-coated Si{sub 3}N{sub 4} film, and the soft X-ray signal from it is detected by an X-ray photodiode (PD) placed below the sample. The SGXM can theoretically achieve better than 5 nm resolution. Our method can be utilized easily for various wet biological samples of bacteria, viruses, and protein complexes.

• OSTI ID: 22199961
• Journal Information: Biochemical and Biophysical Research Communications, Vol. 391, Issue 1; Other Information: Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0006-291X
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
60 APPLIED LIFE SCIENCES
BACTERIA
COMPLEXES
COMPUTERIZED SIMULATION
ELECTRIC POTENTIAL
ELECTRON BEAMS
ELECTRON SCANNING
ELECTRONS
ENERGY ABSORPTION
LIGHT SOURCES
MICROSCOPES
MONTE CARLO METHOD
PROTEINS
SCANNING ELECTRON MICROSCOPY
SILICON NITRIDES
SOFT X RADIATION
SPATIAL RESOLUTION
TITANIUM
VIRUSES