A group of MIT researchers has discovered a technique to enlarge specimens that are easier to image using confocal microscopy.

A group of MIT researchers have come up with a new technique that provides high-resolution images. The method involves embedding tissue sample in a polymer that upon addition of water; swells up and the sample becomes larger.

The researchers suggest that this technique that primarily works using inexpensive, easily accessible chemicals, and microscopes will help many professionals to obtain images with much higher resolution.
The working principle of most microscopes involves use of specific lenses to focus light emitted from the sample into a magnified image.

But one major limitation of this approach remains with the fact that it can’t be used to produce result by visualizing objects that are too smaller than the specific wavelength of the light being used in one particular experiment.

Scientists could finally overcome this limitation, said Ed Boyden, member of MIT’s Media Lab and McGovern Institute for Brain Research. Also, small thin samples work best as far as these super resolution techniques are concerned. “If you want to map the brain, or understand how cancer cells are organized in a metastasizing tumor, or how immune cells are configured in an autoimmune attack, you have to look at a large piece of tissue with nanoscale precision,” added Boyden.

Keeping this in mind, the MIT team decided to come up with ideas that would eventually result in the production of enlarged samples, reported Bioscholar. They first embedded the specimen in a polyacrylate gel. And the sample tissue was labeled with a fluorescent tagged antibody.

After labeling, the precursor was added to the polyacrylate gel and heated. The protein that hold the specimen together were digested causing uniform expansion of it. The specimen was washed in salt-free water to induce a 100-fold expansion in volume.

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With this enlarged specimen, using confocal microscope, the MIT team could obtain resolution down to 70 nanometers. Using this approach, the group also successfully imaged a section of brain tissue 500 by 200 by 100 microns with a standard confocal microscope, it is something difficult to achieve otherwise.

“The other methods currently have better resolution, but are harder to use, or slower,” said Tillberg on behalf of the team. “The benefits of our method are the ease of use and, more importantly, compatibility with large volumes, which is challenging with existing technologies.”

According to the scientists, this technique will be of great help to image brain cells in order to find out the way they connect to each other. Other possible applications of these techniques include in depth analysis of tumor metastasis and angiogenesis and studying autoimmune diseases.

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