Single-particle cryo-EM: alternative schemes to improve dose efficiency.

Area of Science:

• Structural Biology
• Microscopy Techniques
• Biophysics

Background:

• Ionizing radiation, used in electron microscopy (EM), causes radiation damage to biomolecules, altering their structure and composition.
• This damage restricts electron dose in cryogenic electron microscopy (cryo-EM), leading to low signal-to-noise ratios (SNR) and loss of high-resolution details.
• Radiation damage limits the analysis of small particles and heterogeneous samples in EM.

Purpose of the Study:

• To review alternative transmission electron microscopy (TEM) techniques that can overcome the limitations of radiation damage.
• To discuss methods that maximize information transfer and improve SNR for a given electron dose.
• To evaluate the prospects of these techniques for obtaining more structural information from biological samples.

Main Methods:

• Review of advanced TEM techniques including phase plate, multi-pass TEM, off-axis holography, ptychography, and quantum sorter.
• Analysis of how these methods mitigate radiation damage effects on biomolecular imaging.
• Discussion of SNR enhancement and information recovery strategies.

Main Results:

• Alternative TEM techniques offer potential for improved structural analysis despite radiation damage.
• Methods like phase plates and ptychography can enhance contrast and resolution.
• These techniques may allow for imaging of smaller particles and more heterogeneous samples.

Conclusions:

• Radiation damage is an inherent challenge in electron microscopy of biomolecules.
• Exploring and implementing advanced TEM techniques is crucial for pushing the boundaries of structural determination.
• Future research should focus on optimizing these alternative methods for routine cryo-EM applications.