A brief history of expansion microscopy

Recommendable! However, I suspect this expansion introduces distortions or other undesirable artifacts.

"... Using methodology ..., researchers around the world are imaging samples that have been swollen to as much as 20 times their original size so their finest features can be seen more clearly.

“It’s a very different way to do microscopy,”  ... “In contrast to the last 300 years of bioimaging, where you use a lens to magnify an image of light from an object, we physically magnify objects themselves.” Once a tissue is expanded, ... researchers can see more even with widely available, conventional microscopy hardware. ...

introduced this approach, which they named expansion microscopy (ExM), in 2015. Since then, they have been refining the method and adding to its capabilities, while researchers at MIT and beyond deploy it to learn about life on the smallest of scales. ...

To develop expansion microscopy, ... team turned to hydrogel, a material with remarkable water-absorbing properties that had already been put to practical use ... hypothesized that hydrogels could retain their structure while they absorbed hundreds of times their original weight in water, expanding the space between their chemical components as they swell.

After some experimentation, ... team settled on four key steps to enlarging tissue samples for better imaging.

First, the tissue must be infused with a hydrogel.

Components of the tissue, biomolecules, are anchored to the gel’s web-like matrix, linking them directly to the molecules that make up the gel.

Then the tissue is chemically softened and 

water is added.

As the hydrogel absorbs the water, it swells and the tissue expands, growing evenly so the relative positions of its components are preserved. ...

Light microscopes can discriminate between objects that are separated by about 300 nanometers — a limit imposed by the laws of physics.

With expansion microscopy, ... reported an effective resolution of about 70 nanometers, for a fourfold expansion. ..."

A brief history of expansion microscopy | MIT News | Massachusetts Institute of Technology "Since an MIT team introduced expansion microscopy in 2015, the technique has powered the science behind kidney disease, plant seeds, the microbiome, Alzheimer’s, viruses, and more."

Synaptic proteins and their associations to neuronal processes in the mouse primary somatosensory cortex, imaged using expansion microscopy.