When trying to use light and conventional optics to image a biological sample at great detail, one eventually encounters the fact that objects smaller than the light’s wavelength cannot be resolved. While technological tricks have been developed to overcome this limitation in some ways, a team of researchers from MIT and Harvard have instead focused on swelling the sample so it is large enough to be examined in detail using light microscopy.
The technique, called expansion microscopy, increases the volume of small biological samples about 100 fold. This brings a huge set of things, that were previously only seen under an electron microscope, into view with conventional microscopy. Not only is the cost of light microscopy significantly smaller than electron microscopy, the type and quality of imaging offered by a light microscope can provide information on the sample that electron microscopy simply cannot.
Expansion microscopy works by placing a sample to be imaged within a special, carefully produced polymer. Unwanted proteins that hold the tissue intact are chemically removed, while other molecules are essentially glued to the polymer. When water is added, the polymer swells and the embedded sample swells along with it.
The team demonstrated the technology by imaging breast lesions for signs of cancer and identifying the existence of kidney disease by imaging samples at resolutions previously only done with electron microscopy.
Here’s an MIT video about expansion microscopy:
Here’s a website the team setup with all the protocols to get you started: ExpansionMicroscopy.org…