用电子显微镜对比厚厚的生物样本
These videos have been matched automatically. Contact us if they are not relevant.
These videos have been matched automatically. Contact us if they are not relevant.
在PubMed上查看摘要
概括
此摘要是机器生成的。这项研究探讨了T4菌体等厚生物样本的电子显微镜相位和振幅对比. 在玻璃体冰中的生物结构的高分辨率成像中,STEM成像显示了与TEM相比的潜在优势.
科学领域
- 电子显微镜
- 生物成像
- 材料科学
背景情况
- 一致的相位对比度和不一致的振幅对比度对于成像厚厚的生物样本至关重要.
- 了解它们的贡献对于推进冷电子显微镜 (cryo-EM) 技术至关重要.
- 目前方法的局限性需要探索先进的成像方式.
研究的目的
- 对于厚厚的生物标本来说,研究连贯的明亮场相和不连贯的暗场幅度对比的贡献.
- 模拟和比较传输电子显微镜 (TEM) 和扫描传输电子显微镜 (STEM) 的成像能力.
- 在低剂量条件下评估电子能量损失和噪声对图像质量的影响.
主要方法
- 为图像模拟而构建了一个T4菌体模型.
- 在TEM和STEM相对比模拟中使用多切片代码.
- 佩内洛佩蒙特卡洛代码模拟了不连贯的幅度对比.
- 从玻璃体冰中测量了电子能量损失光谱以量化电子分数.
主要成果
- 对于TEM,相对比成像在厚样本中受到电子能量损失峰值的限制.
- 即使在高电子暴露下,噪声也显著限制了冷电磁特征的辨别能力.
- 在振幅和相对比方面,STEM比TEM具有潜在的优势,特别是在弱相极限之外.
结论
- STEM成像显示在厚的生物样本 (例如,1μm冰中的菌体) 中具有成像特征,采集角度优化.
- 建议使用高加速度电压 (约700keV) 进行最佳对比.
- 这些发现有助于优化电子显微镜技术的高分辨率生物成像.
相关概念视频
The wavelengths of visible light ultimately limit the maximum theoretical resolution of images created by light microscopes. Most light microscopes can only magnify 1000X, and a few can magnify up to 1500X. Electrons, like electromagnetic radiation, can behave like waves, but with wavelengths of 0.005 nm, they produce significantly greater resolution up to 0.05 nm as compared to 500 nm for visible light. An electron microscope (EM) can create a sharp image that is magnified up to 2,000,000X.
To be visualized by an electron microscope, either transmission or scanning, biological samples need to be fixed (stabilized) so the electron beam does not destroy them and dried thoroughly (desiccated/dehydrated) so the vacuum does not affect them. Fixation needs to be done as quickly as possible because the sample properties will start changing as soon as it is removed from its natural environment. For example, in a tissue sample, the oxygen levels begin decreasing, causing an altered...
Phase-Contrast Microscopes
In-phase-contrast microscopes, interference between light directly passing through a cell and light refracted by cellular components is used to create high-contrast, high-resolution images without staining. It is the oldest and simplest type of microscope that creates an image by altering the wavelengths of light rays passing through the specimen. Altered wavelength paths are created using an annular stop in the condenser. The annular stop produces a hollow cone of...
Transmission electron microscopy (TEM) can be used to determine the 3D structure of biological samples with the help of techniques such as electron microscope tomography and single-particle reconstruction. While single-particle reconstruction can examine macromolecules and macromolecular complexes in vitro conditions only, tomography permits the study of cell components or small cells in vivo.
Electron Tomography
Electron tomography can be performed either in TEM or STEM (scanning transmission...
Three-dimensional imaging techniques are essential in cell biology, allowing researchers to visualize intricate cellular structures with high resolution. Two prominent methods, Differential Interference Contrast Microscopy (DIC) and Confocal Scanning Laser Microscopy (CSLM), provide distinct advantages for imaging live and thick specimens, respectively.Differential Interference Contrast MicroscopyDIC microscopy enhances contrast in transparent, unstained samples by converting phase...
Two basic types of preparation are used to visualize specimens with a light microscope: wet mounts and fixed specimens.
The simplest type of preparation is the wet mount, in which the specimen is placed in a drop of liquid on the slide. A liquid specimen can be directly deposited on the slide using a dropper. Solid specimens, such as skin scraping, can be placed on the slide before adding a drop of liquid to prepare the wet mount. Sometimes the liquid is simply water, but stains are often added...