Nano Bugle

A window into applied science supported by INL

Taking a (even) closer look at cells

For two decades, scientists have been pursuing a potential new way to treat bacterial infections, using naturally occurring proteins known as antimicrobial peptides (AMPs) that kill bacteria by poking holes in their cell membranes. Now, MIT scientists have recorded the first real-time microscopic images showing the deadly effects of AMPs in live bacteria.
Researchers led by MIT Professor Angela Belcher modified an existing, extremely sensitive technique known as high-speed atomic force microscopy (AFM) to allow them to image the bacteria in real time. Their method, described in the March 14 online edition of Nature Nanotechnology, represents the first way to study living cells using high-resolution images recorded in rapid succession.
Using this type of high-speed AFM could allow scientists to study how cells respond to other drugs and to viral infection, says Belcher, the Germeshausen Professor of Materials Science and Engineering and Biological Engineering and a member of the Koch Institute for Integrative Cancer Research at MIT.
It could also be useful in studying cell death in mammalian cells, such as the nerve cell death that occurs in Alzheimer’s patients, says Paul Hansma, a physics professor at the University of California at Santa Barbara who has been developing AFM technology for 20 years. “This paper is a highly significant advance in the state-of-the-art imaging of cellular processes,” says Hansma, who was not involved in the research.
Atomic force microscopy, invented in 1986, is widely used to image nanoscale materials. Its resolution (about 5 nanometers) is comparable to that of electron microscopy, but unlike electron microscopy, it does not require a vacuum and thus can be used with living samples. However, traditional AFM requires several minutes to produce one image, so it cannot record a sequence of rapidly occurring events.
In recent years, scientists have developed high-speed AFM techniques, but haven’t optimized them for living cells. That’s what the MIT team set out to do, building on the experience of lead author Georg Fantner, a postdoctoral associate in Belcher’s lab who had worked on high-speed AFM at the University of California at Santa Barbara.

The image was taken by Georg Fantner with atomic force microscopy. It shows E. coli bacteria after they have been exposed to the antimicrobial peptide CM15. The peptides have begun destroying the bacteria’s cell walls.

You can read the full article here

Source: MIT News office

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March 15, 2010 - Posted by | Nano News

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