'We are trying the almost impossible. That's what we do here every day.'

Tjerk Oosterkamp, Professor of Experimental Physics, has an ambitious goal: an MRI scanner that can distinguish individual atoms in biological materials. He has received a Vici grant of 1.5 million euros to develop the device.

Biological nano-devices

Oosterkamp: 'Proteins in a living cell are actually biological nano-devices, and in many cases we don't understand what they look like or how they work. But that's information we do need, for example to develop specific medicines. That's particularly true for proteins on cell membranes.' 

Recording with an electron microscope of a wafer-thin silicon needle picking up a magnetic nanosphere. This is the heart of the MRI-AFM under development.

Recording with an electron microscope of a wafer-thin silicon needle picking up a magnetic nanosphere. This is the heart of the MRI-AFM under development.

Scanning the surface of proteins

He is currently developing an atomic scanning microscope (AFM) that also works as an MRI scanner. This device consists of a probe just nanometres in size, that scans the surface of a protein or other large molecule, atom by atom. At the tip of the probe there is a tiny magnetic ball. This ball is able to 'sense' the magnetism of atom nuclei or índividual electrons in the protein molecule, because it is a minute magnet itself. Using MRI (magnetic image resonance), you can selectively reverse the magnet of a limited number of atoms, using a pulse of radiation from outside, so that the needle only registers the nitrogen atoms in a limited part of a protein molecule. 

Fine mechanics

The technical challenges are enormous: any vibration is disastrous, which is why an MRI-AFM has to be suspended from a multi-stage sprung frame, and it has to work at a temperature of just above absolute zero (-273 degrees celsius).

The Vici grant, that is spread over five years, is primarily intended to appoint two PhD candidates, a postdoc and a technical specialist. 'I can't build this equipment without professional fine-mechanical and electronics specialists,' Oosterkamp stresses. 'Leiden University has no funds to hire such people itself.'

The atomic scanning microscope is built on a chip in the lowest section. The other compartments contain the refrigeration and measuring equipment. The complete device will be suspended in a cryogenic state, in a large thermos vessel with liquid helium.

The atomic scanning microscope is built on a chip in the lowest section. The other compartments contain the refrigeration and measuring equipment. The complete device will be suspended in a cryogenic state, in a large thermos vessel with liquid helium.

Emotional problem

Experimental physicists have to have a high frustration tolerance. In many instances, what you have built doesn't work, and you can't find out why not. Oosterkamp: 'That can be a major emotional problem, particularly for PhD candidates: how do you manage to keep going for so long on a project when for months you have made no progress? It's something I find easier these days: I have several PhD candidates and postdocs, and there's always at least one pot still bubbling away.' Oosterkamp himself believes there's a 75% chance that the MRI-AFM will in the end achieve a resolution of about one nanometer (some 5 atoms broad) and there's a 50% chance that it will distinguish atoms in a random biological molecule.

Better than the best

This goal is at least ten years in the future. So, how do you manage to maintain the impetus of such research? 'You have to keep asking yourself what the benefit will be for the Netherlands Limited. We are trying to do something that's almost impossible. But saying 'it can't be done' isn't the way I look at life. I always tell PhD candidates and postdocs: think of something that is better than the best that's currently available. It's possible, because that's what we do here every day. We have also set up a company that will get the equipment we develop in a state wher eit can be used by other institutions as quickly as possible. Then other people don't need to reinvent the wheel. This will multiply our research output, although it won't appear on my publication list. That's not a problem, though. I am a believer; I am not doing this just for myself.'

(19 February 2013)

See also

Studying in Leiden

Bachelor's
Natuurkunde

Master's
Physics

Fundamentals of Science is ione of the six themes for research at Leiden University.


Last Modified: 25-02-2013