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Biomolecular Movie-Making with Atomic Force Microscopy

Biomolecular Movie-Making with Atomic Force Microscopy | Science Communication from mdashf | Scoop.it

Toshio Ando and co-workers at Kanazawa University have developed and used high-speed atomic force microscopy (HS-AFM) to achieve direct visualization of dynamic structural changes and processes of functioning biological molecules in physiological solution — creating microscopic movies of unprecedented sub-100-ms temporal resolution and submolecular spatial resolution.

 

To produce an image, HS-AFM acquires information on sample height at many points by tapping the sample with the sharp tip of a tiny cantilever and dragging the sharp tip of a tiny cantilever across the sample. Depending on the application, this might involve recording the distance of deflection, the amplitude and phase of oscillations, or the resonant frequency of the cantilever.

 

Ando and co-workers use very small cantilevers that provide 10 to 20 times the sensitivity of larger, conventional cantilevers. Copies of their home-made apparatus are now commercially available through the manufacturer Research Institute of Biomolecule Metrology Co., Ltd in Tsukuba, and record images at least ten times more quickly than their competitors.


Via Dr. Stefan Gruenwald
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DNA directly imaged with electron microscope for the first time

DNA directly imaged with electron microscope for the first time | Science Communication from mdashf | Scoop.it

It's the most famous corkscrew in history. Now an electron microscope has captured the famous Watson-Crick double helix in all its glory, by imaging threads of DNA resting on a silicon bed of nails. The technique will let researchers see how proteins, RNA and other biomolecules interact with DNA.

 

The structure of DNA was originally discovered using X-ray crystallography. This involves X-rays scattering off atoms in crystallised arrays of DNA to form a complex pattern of dots on photographic film. Interpreting the images requires complex mathematics to figure out what crystal structure could give rise to the observed patterns.

 

The new images are much more obvious, as they are a direct picture of the DNA strands, albeit seen with electrons rather than X-ray photons. The trick used by Enzo di Fabrizio at the University of Genoa, Italy, and his team was to snag DNA threads out of a dilute solution and lay them on a bed of nanoscopic silicon pillars.

 

The team developed a pattern of pillars that is extremely water-repellent, causing the moisture to evaporate quickly and leave behind strands of DNA stretched out and ready to view. The team also drilled tiny holes in the base of the nanopillar bed, through which they shone beams of electrons to make their high-resolution images. The results reveal the corkscrew thread of the DNA double helix, clearly visible. With this technique, researchers should be able to see how single molecules of DNA interact with other biomolecules.


Via Dr. Stefan Gruenwald
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