Grid batch-dependent tuning of glow discharge parameters.

Area of Science:

• Structural Biology
• Materials Science
• Microscopy

Background:

• Cryo-electron microscopy (cryo-EM) sample preparation is critical for high-resolution 3D reconstructions.
• Inconsistent results, including particle aggregation and altered complex conformation, can arise from suboptimal grid preparation.
• Variations in cryo-EM 3D reconstructions were observed to correlate with specific grid batches.

Purpose of the Study:

• To investigate the causes of systematic variations in cryo-EM 3D reconstructions linked to grid batches.
• To identify and characterize the physical and chemical properties of cryo-EM grids influencing sample preparation outcomes.
• To establish methods for diagnosing and resolving grid preparation-related issues in cryo-EM.

Main Methods:

• Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) for morphological analysis of grid surfaces.
• Auger Electron Spectroscopy (AES) for elemental composition analysis of grid surfaces.
• Infrared Interferometry for assessing surface properties and ice thickness.
• Glow discharge optimization as a parameter adjustment.

Main Results:

• TEM and SEM revealed morphological differences in grid batches.
• AES indicated variations in surface elemental composition across different grid batches.
• Infrared Interferometry provided insights into surface characteristics affecting ice formation.
• Adjusting glow discharge parameters successfully mitigated reconstruction inconsistencies.

Conclusions:

• Grid batch variations can significantly impact cryo-EM sample quality and reconstruction outcomes.
• A multi-technique approach (TEM, SEM, AES, Infrared Interferometry) is effective for diagnosing grid preparation issues.
• Optimized glow discharge treatment is crucial for achieving homogeneous ice and reliable particle distribution in cryo-EM.