New Technique for Nanoscale Imaging in Cells Using Conventional Microscopes.

MIT researchers have developed a technique to expand tissue 20-fold, enabling high-resolution imaging of synapses and microtubules using a conventional light microscope. In the left image, presynaptic proteins are labeled in red and postsynaptic proteins in blue, with each blue-red "sandwich" representing a synapse.

MIT researchers have developed a groundbreaking method that enables nanoscale imaging of cellular structures using conventional light microscopes. This innovative approach involves expanding tissue samples 20-fold in a single step, making high-resolution imaging accessible to many biology labs without the need for expensive super-resolution microscopes.

Laura Kiessling, Novartis Professor of Chemistry at MIT, emphasized the significance of this method, stating, “This democratizes imaging.” With this technique, researchers can visualize organelles and protein clusters at a resolution of approximately 20 nanometers, revealing details about cellular components that were previously invisible with standard imaging tools.

Evolution of Expansion Microscopy.

Originally introduced in 2015, expansion microscopy involved embedding tissue in a polymer, disrupting the proteins that bind tissues, and then swelling the gel with water to separate biomolecules. The initial method achieved a fourfold expansion, allowing for imaging at around 70 nanometers. Subsequent modifications increased the expansion to 20-fold but required multiple steps.

The new study, led by graduate student Shiwei Wang and Tay Won Shin, aims to simplify the process by achieving the 20-fold expansion in a single step. The researchers designed a robust gel from N,N-dimethylacrylamide (DMAA) and sodium acrylate, which can spontaneously form crosslinks, enhancing its mechanical stability.

Methodology and Advantages.

To optimize gel formation, the researchers removed oxygen from the polymer solution, minimizing side reactions that could compromise crosslinking. Following gel preparation, specific bonds in the tissue are broken, allowing for the addition of water and subsequent expansion.

While the technique involves more sample preparation than some super-resolution methods, it streamlines the imaging process, particularly for three-dimensional imaging. The detailed step-by-step protocol is provided in the study for easy implementation.

Applications and Future Prospects.

Using this method, researchers successfully imaged intricate structures in brain cells, such as synaptic nanocolumns that facilitate neurotransmitter communication. They also explored microtubules and mitochondria in cancer cells, enhancing our understanding of cellular organization.

The researchers envision that this accessible technique could enable any biology lab to conduct high-resolution imaging using standard equipment and readily available chemicals. Wang remarked on the potential impact, suggesting that this advancement will allow labs to achieve nanoscale resolution previously limited to specialized facilities.

The research was supported by various funding bodies, including the U.S. National Institutes of Health and the Howard Hughes Medical Institute, highlighting its broad significance in advancing biological imaging.