‘Artificial atoms’ allow for sensing magnetic fields of individual cells
February 13, 2013
Researchers in Spain and Australia have developed a new technique that similar to MRI but with the high resolution and sensitivity need to scan individual cells.
The researchers, from the Institute of Photonic Sciences (ICFO), in collaboration with the CSIC and Macquarie University in Australia, are led by ICFO Prof. Romain Quidant. They used “artificial atoms” — diamond nanoparticles doped with nitrogen impurity — to probe very weak magnetic fields such as those generated in some biological molecules.
A conventional MRI registers the magnetic fields of atomic nuclei in our bodies which have been previously excited by an external electromagnetic field. The collective response of all of these atoms makes it possible to diagnose and monitor the evolution of certain diseases. However, MRI is limited to a resolution of millimeters.
The new technique extends the resolution at the nanometer scale (nearly one million times smaller than the millimeter), making it possible to measure very weak magnetic fields, such as those created by proteins.
“Our approach opens the door for the performance of magnetic resonances on isolated cells which will offer new sources of information and allow us to better understand the intracellular processes, enabling noninvasive diagnosis,” explains Michael Geiselmann, ICFO researcher who conducted the experiment.
Near-absolute-zero temperatures not required
Until now, it has only been possible to reach this resolution in the laboratory, using individual atoms at temperatures close to absolute zero (approx. -273 degrees Celsius.)
Individual atoms are structures that are highly sensitive to their environment, with a great ability to detect nearby electromagnetic fields. The challenge these atoms present is that they are so small and volatile that in order to be manipulated, they must be cooled to temperatures near absolute zero, making them useless for ordinary medical diagnosis.
Artificial atoms used by Quidant and his team are formed by a nitrogen impurity captured within a small diamond crystal. “This impurity has the same sensitivity as an individual atom but is very stable at room temperature due to its encapsulation. This diamond shell allows us to handle the nitrogen impurity in a biological environment and, therefore, enables us to scan cells,” says Quidant.
To trap and manipulate these artificial atoms, researchers use laser light. The laser works like tweezers, leading the atoms above the surface of the object to study and extract information from their tiny magnetic fields.
The new technique could revolutionize the field of medical imaging, allowing for substantially higher sensitivity in clinical analysis and improved capacity for early detection of diseases.
The research was supported by Cellex Barcelona.