Team creates MRI for the nanoscale

Feb 13, 2013
Team creates MRI for the nanoscale
A tiny defect, called a nitrogen vacancy (NV), inside a diamond enabled researchers to detect the magnetic resonance of organic molecules in the same way an MRI produces images of a tissue or an organ. Credit: T. Staudacher and F. Reinhard

Magnetic resonance imaging (MRI) reveals details of living tissues, diseased organs and tumors inside the body without x-rays or surgery. What if the same technology could peer down to the level of atoms? Doctors could make visual diagnoses of a person's molecules – examining damage on a strand of DNA, watching molecules misfold, or identifying a cancer cell by the proteins on its surface.

Now Dr. Carlos Meriles, associate professor of physics at The City College of New York, and an international team of researchers at the University of Stuttgart and elsewhere have opened the door for nanoscale MRI. They used tiny defects in diamonds to sense the magnetic resonance of molecules. They reported their results in the February 1 issue of Science.

"It is bringing MRI to a level comparable to an atomic force microscope," said Professor Meriles, referring to the device that traces the contours of atoms or tugs on a molecule to measure its strength. A nanoscale MRI could display how a molecule moves without touching it.

"Standard MRI typically gets to a resolution of 100 microns," about the width of a human hair, said Professor Meriles. "With extraordinary effort," he said, "it can get down to about 10 microns" – the width of a couple of . MRI would have a resolution 1,000 to 10,000 times better.

To try to pick up magnetic resonance on such a small scale, the team took advantage of the spin of protons in an atom, a property usually used to investigate . In particular, they used minute imperfections in diamonds.

Diamonds are crystals made up almost entirely of . When a lodges next to a spot where a carbon atom is missing, however, it creates a defect known as a nitrogen-vacancy (NV) center.

"These imperfections turn out to have a spin – like a little compass – and have some remarkable properties," noted Professor Meriles. In the last few years, researchers realized that these NV centers could serve as very sensitive sensors. They can pick up the magnetic resonance of nearby atoms in a cell, for example. But unlike the atoms in a cell, the NVs shine when a light is directed at them, signaling what their spin is. If you illuminate it with green light it flashes red back.

"It is a form of what is called optically detected magnetic resonance," he said. Like a hiker flashing Morse code on a hillside, the sensor "sends back flashes to say it is alive and well."

"The NV can also be thought of as an atomic magnet. You can manipulate the spin of that atomic magnet just like you do with MRI by applying a radio frequency or radio pulses," Professor Meriles explained. The NV responds. Shine a green light at it when the spin is pointing up and it will respond with brighter red light. A down spin gives a dimmer red light.

Professor Mireles has written on the theoretical underpinnings of the work and proposed the the project to the team, led by Professor Jörg Wrachtrup—a physicist at the University of Stuttgart in Germany—with the assistance of postdoctoral researcher Friedemann Reinhard and collaborators from the University of Bochum and the University of Science and Technology of China. Professor Wrachtrup heads a leading group studying such defects.

In the lab, graduate student Tobias Staudacher—the first author in this work—used NVs that had been created just below the diamond's surface by bombarding it with nitrogen atoms. The team detected within a film of organic material applied to the surface, just as one might examine a thin film of cells or tissue.

"Ultimately," said Professor Meriles, "One will use a nitrogen-vacancy mounted on the tip of an – or an array of NVs distributed on the diamond surface – to allow a scanning view of a cell, for example, to probe nuclear spins with a resolution down to a nanometer or perhaps better."

Explore further: IHEP in China has ambitions for Higgs factory

More information: Science, 1 February 2013: 561 563. DOI:10.1126/science.1231675

Related Stories

Nanoscale MRI being developed

Feb 01, 2013

(Phys.org)—Two independent groups of scientists in the U.S. and Germany have reduced magnetic resonance imaging (MRI) down to the nanoscale, which may enable them in the future to non-destructively detect ...

New study may lead to MRIs on a nanoscale

Feb 23, 2012

(PhysOrg.com) -- Magnetic resonance imaging (MRI) on the nanoscale and the ever-elusive quantum computer are among the advancements edging closer toward the realm of possibility, and a new study co-authored ...

A new spin in diamonds for quantum technologies

Dec 20, 2011

(PhysOrg.com) -- To explore the future potential of diamonds in quantum devices, researchers from Macquarie University have collaborated with the University of Stuttgart and University of Ulm in Germany towards ...

Recommended for you

IHEP in China has ambitions for Higgs factory

2 hours ago

Who will lay claim to having the world's largest particle smasher?. Could China become the collider capital of the world? Questions tease answers, following a news story in Nature on Tuesday. Proposals for ...

The physics of lead guitar playing

4 hours ago

String bends, tapping, vibrato and whammy bars are all techniques that add to the distinctiveness of a lead guitarist's sound, whether it's Clapton, Hendrix, or BB King.

The birth of topological spintronics

5 hours ago

The discovery of a new material combination that could lead to a more efficient approach to computer memory and logic will be described in the journal Nature on July 24, 2014. The research, led by Penn S ...

The electric slide dance of DNA knots

8 hours ago

DNA has the nasty habit of getting tangled and forming knots. Scientists study these knots to understand their function and learn how to disentangle them (e.g. useful for gene sequencing techniques). Cristian ...

User comments : 0