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(Chem) Atomic Force Microscopy: Atom-sized Biology

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PostPosted: Thu Feb 16, 2006 8:11 am    Post subject: (Chem) Atomic Force Microscopy: Atom-sized Biology Reply with quote

New Technique Photographs Atom-sized Biology
By Scott Fields
Special to LiveScience
posted: 15 February 2006
02:00 pm ET

Scientists have successfully imaged tiny biological structures that are normally hidden by surrounding material.

The structures are less than 150 nanometers across. The details in these images can be less than 10 nanometers. That's 10 billionth of a meter, just the width of a handful of atoms laid end-to-end.

This technology can pinpoint structures normally hidden among other, similar structures, almost like taking a snapshot of the proverbial needle in a haystack while passing overhead in a jumbo jet. And someday this work may allow medical technicians to process biopsies more efficiently.

The structure in question was a single protein fiber that was embedded in tooth enamel. But this technique could work with any human, animal, or plant tissues, says Sergei Kalinin, a research scientist at the Oak Ridge National Laboratories in Oak Ridge, Tennessee.

Kalinin and his colleagues at North Carolina State University in Raleigh form the images by harnessing the piezoelectric effect. Piezoelectric materials either move when an electric current is applied to them or produce an electric current when they are compressed. Perhaps the best known piezoelectric materials are quartz crystals, whose electricity-prodded vibrations controlled oscillators in watches and early radios.

Many biological materials, such as bones, tendons, and wood, also move slightly when electrically shocked.

Using a custom-built tip extension for a scanning force microscope, the scientists direct a tiny voltage, which alternates polarity 50,000 times per second, at small groups of piezoelectric-sensitive molecules. The molecules then vibrate 50,000 times per second while the surrounding non-piezoelectric materials remain still.

By tracking patterns the vibrating molecules make, the scientists produce images of tiny structures that otherwise would be lost among other, non-piezoelectric, materials, such as hydroxyapatite, which is a type of calcium.

This technology, Kalinin says, works at a material's surface. Although the most likely near-future applications are in fundamental research, he says, it is possible that someday it will allow faster and cheaper analysis of biopsy samples. Current imaging technologies require technicians to spend time staining biopsy samples. The new technique wouldn't require a stain.

Another possible future application would be to image and then use the same tool, at a higher voltage, to selectively zap viral contaminants from biological samples.

"One of the things we have done recently is to use electrical bias to selectively modify, for example, the tobacco mosaic virus," Kalinin explained. The virus affects flowers and vegetables worldwide.

"If we have viruses on the surface, we can see them," he said. "Secondly, we can select the viruses we don't like and blow them up by applying a high enough electric field."


Questions to explore further this topic:

What are piezoelectrics?

What are some examples of piezoelectric materials?

What are some of the known applications of piezoelectric materials?

How are piezoelectric materials used in atomic force microscopy?

What is an atomic force microscope?

A virtual tour of scanning probe microscopes

A gallery of atomic images


Last edited by adedios on Sat Jan 27, 2007 4:12 pm; edited 2 times in total
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PostPosted: Fri Aug 04, 2006 12:46 pm    Post subject: Technique finds application in neuroscience Reply with quote

University of California - Riverside
3 August 2006

Technique used commonly in physics finds application in neuroscience

Method can help develop high-sensitive microsensors
Riverside, Calif. -- To understand how brain cells release compounds (or transmitters) used when the cells communicate with each other, Vladimir Parpura, associate professor of neuroscience, and Umar Mohideen, professor of physics at UC Riverside, devised a new technique, used commonly in physics, that can be applied now to the study of a wide range of biological processes and interactions.

The researchers, who performed their experiments on brain proteins called SNAREs, published their results in the July issue of Biophysical Journal.

The technique, commonly referred to as Atomic Force Microscopy, uses the deflection of microfabricated membranes of silicon nitride, about 100 times thinner than the human hair, to measure very small forces. Using this technique on rat brain proteins, the researchers were able to measure the bonding between single protein molecules that are involved in the release of the neurotransmitters. They also were able to classify the strength of the molecular interactions (bonding) between 3 of the SNARE proteins that participate in the process.

SNARE proteins are located on vesicles (tiny membrane-encased packets that contain neurotransmitters or enzymes) and the plasma membrane of brain cells. These proteins are thought to play a key role in the final fusion of the synaptic vesicle with the plasma membrane, a process that makes communication between cells possible.

"Our results shed new light on how these proteins are involved in exocytosis - the process by which a biological cell releases substances into its environment," Parpura said. "We now understand better how these proteins interact at the molecular level and we can apply this to improve our detection of toxins acting on these proteins."

The researchers used the technique also to develop a sensor for detecting botulinum toxin, responsible for an often fatal type of food poisoning.

"Our sensor is extremely sensitive because it is capable of detecting interactions between two single molecules," Mohideen said. "As a result, the sample size you need for testing can be extremely small, of the order of a few molecules."

The UCR technique paves the way for developing high-sensitive microsensors for the rapid detection of neurotoxins.

The research team also included UCR's W. Liu and Vedrana Montana and the University of Wisconsin's Jihong Bai and Edwin R. Chapman.

The research was funded by grants from the National Institutes of Health, the American Heart Association, the National Institute of Standards and Technology, and the Department of Defense/Defense Advanced Research Planning Agency/Defense Microelectronics Activity.

The University of California, Riverside is a major research institution. Key areas of research include nanotechnology, health science, genomics, environmental studies, digital arts and sustainable growth and development. With a current undergraduate and graduate enrollment of more than 16,600, the campus is projected to grow to 21,000 students by 2010. Located in the heart of Inland Southern California, the nearly 1,200-acre, park-like campus is at the center of the region's economic development. Visit or call 951-UCR-NEWS for more information. Media sources are available at
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