Cryo-Transmission Electron Microscope (Cryo-TEM)

Glacios 2 Cryo-TEM
Glacios 2 is a 200 kV, FEG Cryo Transmission Electron Microscope (Cryo-TEM), for the investigation of biological samples in the fields of structural biology and cell biology. In particular, versatility of a 200 kV system allows:

• Single Particle Analysis (SPA) high-resolution data acquisition and sample quality assessment.
• Micro-Electron Diffraction (Micro-ED) studies of crystalline samples whose sizes are too small for X-ray diffraction experiments.
• Cryo-Electron Tomography (Cryo-ET) to investigate both particles (tomography of reconstructed systems) and cellular/fixed samples (tomography of cellular-lamella systems). The microscope has high level of automation and user guidance of experimental settings, enabling scientists to efficiently unravel protein structures in 3D, as well as understand their functional context in the biological cell.
  
  Microscope
• Extreme high-brightness field emission gun (X-FEG) with a flexible accelerating voltage from 80 to 200 kV to generate an appropriate operational electron beam with high brightness, high coherence, and high stability for high resolution imaging.
• Objective lens designed to guarantee high contrast on both thick and thin samples, for cryo-tomography, Single Particle Analysis (SPA), and Micro Electron Diffraction (Micro-ED) applications.
• Cryogenic sample holder and automatic loading system for automated and contamination-free loading for up to 12 sample grids, operating with a single vacuum interruption. This automatic loader design enables high sample throughput.
  
  Detector
• High DQE electron detector.
• 16-megapixel digital camera designed for imaging and diffraction applications is retractable and mounted under the microscope in an on-axis position. Camera has 4K x 4K pixels, with 14x14 μm² pixel size.
• Native file format of the camera is EER (Electron Event Representation), which is a lossless, highly efficient data compression format that offers users the option to store full temporal and spatial (super) resolution or convert directly into dose-fractions for storage in traditional MRC or LZW TIFF images. During EER, only counted electron events are stored, thus significantly reducing the size of the files without losing critical information.
  
  Performance
  Extremely stable sample stage under cryogenic conditions. The improved drift ensures faster and more reliable data collection.
  Maximum drift values after specimen exchange:
• 2 min: 1.2 nm/s (Grid Atlas)
• 5 min: 0.4 nm/s (Target Areas)
• 15 min: 0.1 nm/s (Start Tomo)
• 30 min: 0.05 nm/s (Start EPU)
• 60 min: 0.035 nm/s (Drift Settling)
  During measurement, transmission loss due to the effect of ice growth is ≤ 2% per 24 h.
• Geometrical distorsion: < 0.5%
• Chromatic distorsion: < 0.4%
• Non-isochromaticity: < 1.0 eV
  
  Software
• Automated sample screening software that allows the acquisition of grid atlas overviews of a selection of the grids that are stored in the autoloader.
• Software can also categorize the properties of the ice films in the grid squares, providing initial data for a specimen quality assessment by the user.
• Software enables queuing multiple automatic sessions for the different grids in the autoloader, to automatically set-up and execute multiple unattended sessions. Software also facilitates efficient scheduling of work for multi-user facilities, and it facilitates fast screening with queuing short runs to be executed overnight.
• The software acts as a single user interface for setting up and executing the Single-Particle Analysis workflow on the microscope. This workflow includes the required (auto) alignment routines, and setup parameters for screening or high-resolution data acquisition.

📍The system is located at CNR-IOM.

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