Nanofluidic chips for reproducible cryo-EM sample preparation with picoliter sample volumes

Cryogenic transmission electron microscopy (cryo-EM) is a technique for high-resolution imaging of radiation-sensitive biological macromolecules under near-native conditions.

Cryo-EM sample preparation techniques rely on rapid cooling of an aqueous suspension of biological macromolecules to obtain a thin layer of amorphous ice containing the solute.

Problems associated with current implementations are considered a major bottleneck to realizing the full potential of cryo-EM: excessive sample consumption, the difficulty to reproducibly obtain ice conditions suitable for high-resolution imaging and the extensive contact of solute molecules with a large air-water interface result in only a small fraction of the imaged molecules contributing useful information for the final 3D reconstruction.

Poor time resolution of these methods furthermore precludes the visualization of dynamic structural changes that provide critical biological insight. In our laboratory we have developed technology to design nanofluidic MEMS devices suitable for cryo-EM imaging.

We here propose to explore product development of a nanofluidic chip for reproducible sample preparation with picoliter volumes.

The sample is contained in nanochannels formed between membranes of an electron-transparent material, thereby controlling ice thickness and avoiding formation of an air-water-interface.

This method has all features to push cryo-EM to new frontiers: it requires minute amounts of sample, robustly provides uniform and customizable thickness gradients across the sampling area at a time resolution that is limited only by the vitrification process itself.

Our CryoChip will provide entirely new opportunities for time-resolved cryo-EM imaging and high-throughput applications in structure-based drug design for pharmaceutical industry.

We will liaise with an industrial partner experienced in MEMS probe fabrication to explore processoptimization and viability of larger-scale production.