Ensuring contamination-free lift-out lamellae for cryo-ET with the CERES Clean Station

Jean Daraspe, Electron Microscopy Facility, University of Lausanne (UNIL)

Challenges in Cryo-ET Sample Preparation

Cryo-electron tomography (cryo-ET) requires extreme precision at every step of sample preparation. A persistent challenge for Jean Daraspe, Expert Scientist at the Electron Microscopy Facility (EMF) at the University of Lausanne (UNIL), was ice contamination during the transfer of lamellae from the Thermo Fisher Aquilos cryo-FIB to the Titan Krios microscope.

One of the most frustrating problems was losing imaging surface area due to contamination. Without a fully humidity-controlled environment, which is expensive and difficult to maintain, we constantly struggled with sample degradation.

Integrating the CERES Clean Station

To overcome these challenges, the EMF at UNIL integrated the CERES Clean Station into its workflow. The system provides an extremely dry atmosphere ensuring that sample transfers are conducted in an optimal environment, free from moisture-induced contamination.

At first, working with the Clean Station took some practice, but once we became familiar with it, the improvement was clear. We no longer need to rush our transfers—we can work confidently, knowing that the controlled environment will protect our samples.

The ability to conduct uninterrupted, contamination-free transfers from the Aquilos shuttle to the Titan cassette in the same station has had a measurable impact on research efficiency and data quality.

Measurable Improvements in Research

The CERES Clean Station has provided immediate and visible benefits, especially in maintaining the integrity of grids and lamellae.

Contamination-Free Receiver Grids In cryo-ET workflows, receiver grids are crucial for the cryo-lift-out process, where lamellae are deposited after extraction with a lift-out needle. Any contamination can reduce usable surface area.

Before, contamination on our receiving grids often rendered parts of them unusable. Now, all grid squares remain clean, making the deposition process much easier and more reliable.

This is especially important for SOLIST (Serialized On-Grid Lift-In Sectioning for Tomography), a method that enhances cryo-ET sample preparation for complex specimens like tissues. Implementing the CERES Clean Station has significantly improved the quality of these receiver grids. Its ultra-dry environment ensures that all grid squares remain clean, facilitating a more reliable deposition process.

Enhanced TEM Imaging

In the TEM, contamination used to appear during tilt series acquisition, masking exposure areas and disrupting tracking focus. With the Clean Station, the entire surface of the lamellae is available for imaging, eliminating these issues.

Key Features That Make a Difference

For Daraspe and his team, the most valuable feature of the Clean Station is its ability to facilitate direct, contamination-free transfers.

Being able to move grids directly from the Aquilos shuttle to the Titan cassette in the same station, without contamination, is a game-changer. It removes unnecessary handling steps and exposure to ambient humidity, making a huge difference in sample quality.

A Strong Recommendation for Cryo-ET Researchers

Given the challenges of maintaining a fully humidity-controlled lab, Daraspe sees the CERES Clean Station as an efficient and practical alternative for any facility working with cryo-ET.

I would absolutely recommend the CERES Clean Station to other researchers. While working in a glove box requires some adjustment, it is far better than spending days on Lift-Out projects only to end up with contaminated lamellae. The Clean Station is a compact, energy-efficient solution that solves a major problem in our workflow.

By integrating the CERES Clean Station, the Electron Microscopy Facility at UNIL has achieved more consistent, contamination-free cryo-ET sample preparation, ultimately leading to better imaging results and more reliable data.