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Updated: May 12, 2025
08:04
Preparation and Observation of Thick Biological Samples by Scanning Transmission Electron Tomography
Published on: March 12, 2017
9.2K
Comprehensive Comparison Between STEM-HAADF and TEM Bright-field Mode for Imaging Resin Embedded Biological Samples
Kayla Lynne Haberman1, Jelena Danilovic Lukovic2, Snezana Kovacevic2
1Department of Biology, Baylor University, One Bear Place #97388, Waco 76798-7388, TX, USA.
Summary
Scanning transmission electron microscopy (STEM) with a high-angle annular dark-field (HAADF) detector offers superior image quality for biological samples compared to traditional bright-field transmission electron microscopy (TEM). This advanced technique enhances contrast and signal-to-noise ratio, making post-staining unnecessary for many samples.
Area of Science:
- Electron microscopy
- Biological imaging
- Materials science
Background:
- Transmission electron microscopy (TEM) in bright-field mode is standard for resin-embedded biological samples.
- Modern TEMs offer scanning TEM (STEM) mode with high-angle annular dark-field (HAADF) detection.
Purpose of the Study:
- To compare image quality between TEM bright-field and STEM-HAADF modes for various biological samples.
- To evaluate the necessity of post-contrasting for biological samples in different imaging modes.
Main Methods:
- Resin-embedded biological samples (yeast, algae, plant leaves, human cells, animal tissues) were imaged using both TEM bright-field and STEM-HAADF modes.
- Image quality was assessed based on contrast, brightness, and signal-to-noise ratio.
- Comparison included samples with and without post-contrasting (uranyl acetate, lead citrate).
Main Results:
- STEM-HAADF mode generally yielded superior image quality (contrast, brightness, signal-to-noise ratio) compared to TEM bright-field.
- Samples without post-contrasting showed significantly reduced graininess in STEM-HAADF mode.
- STEM-HAADF mode provided better image quality for unstained algae, MCF7, and liver cells, with absence of artifacts seen in TEM mode.
Conclusions:
- STEM-HAADF mode presents significant advantages for imaging resin-embedded biological samples, especially those with low intrinsic contrast or unstained sections.
- Post-contrasting may be rendered unnecessary for certain biological samples when using STEM-HAADF, simplifying sample preparation.
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