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.
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 quantum computing. In particular, they used minute imperfections in diamonds.
Diamonds are crystals made up almost entirely of carbon atoms. When a nitrogen atom lodges next to a spot where a carbon atom is missing, however, it creates a defect known as a nitrogen-vacancy (NV) center.
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.
“Ultimately,” said Professor Meriles, “One will use a nitrogen-vacancy mounted on the tip of an atomic force microscope – 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.”
This story is reprinted from material from The City College of New York, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.