Brussels, 13 November 2025 – Researchers at the VIB-VUB Center for Structural Biology have developed a new microfluidics-based workflow that enables high-resolution cryogenic electron microscopy (cryo-EM) structure determination from extremely small quantities of starting material. Their study, published in Nature Methods, introduces the MISO (microfluidic protein isolation) platform, which integrates protein purification and cryo-EM grid preparation into a single streamlined process. This approach reduces sample requirements by 100- to 1,000-fold compared to conventional workflows.

Cryo-EM has become a core method for visualizing biological macromolecular structures at near-atomic resolution. Yet, current workflows typically require large-scale protein production and extensive purification steps, even though only picogram quantities of protein are finally imaged. By miniaturizing purification and delivering purified protein directly onto cryo-EM grids, MISO bridges this gap and enables the entire workflow to be carried out in just a few hours from cell lysis to vitrified grids.

“MISO fundamentally changes what is possible in structural biology,” said Prof. Rouslan Efremov (VIB-VUB), senior author of the study. “We can now move from cells to a near-atomic resolution structure in the same day, using a fraction of the biological starting material normally required.”

The study demonstrates that MISO can deliver high-resolution cryo-EM structures for both soluble and membrane proteins. β-galactosidase was successfully purified and resolved starting from the biomass of a single E. coli colony. Structures of the proton-activated chloride channel TMEM206 were obtained from the equivalent of only half of a single mammalian cell culture dish.

The researchers, including members from the lab of Janine Brunner (VIB-VUB) and Novartis, further showed that MISO can support protein discovery workflows. In one case, an unknown membrane protein purified using MISO was identified directly from its cryo-EM map, highlighting the platform’s potential for characterizing low-abundance or previously uncharacterized complexes.

According to Dr. Gangadhar Eluru (VIB-VUB), first author of the study, “This represents a major step toward making cryo-EM more accessible and more efficient. For many projects, the challenge is not microscopy, but obtaining enough high-quality protein. MISO addresses this challenge directly.”

Looking ahead, the researchers anticipate that further miniaturization of the purification and sample-handling steps may enable cryo-EM structure determination from even smaller biological inputs, potentially reaching the scale of primary cells, organoids, or biopsy samples.

Funding

This work was supported by VIB, FWO, and ERC.