Scientists create MRI for nanoscale imaging

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.

Magnetic resonance imaging (MRI) reveals details of living tissues, diseased organs and tumours 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
1 February 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 blood cells. Nanoscale 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 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) centre.