Nanodiamonds: "Our goal is not to be able to diagnose a specific disease, but to offer medicine a universal tool"

Interview with Dr. Patrick Happel, RUBION - Ruhr University Bochum

They are not just "a girl's best friend"1, but are also important helpers in medicine: diamonds. Yet the latter are so tiny that they are not visible to the naked eye. Dr. Patrick Happel at the Ruhr University Bochum in Germany studies so-called nanodiamonds. Someday soon, they are supposed to help in significantly improving medical imaging.


Photo: Patrick Happel

Dr. Patrick Happel; © RUBION - Ruhr-Universität Bochum

Why are nanodiamonds the ideal candidates for tracking in the body?

Patrick Happel
: In most cases, only a marker renders the detection of nanoparticles possible. It is generally located on the surface of the nanoparticle. Such a bond can be broken however. Although you always know while measuring that a detected signal comes from the marker, you cannot be sure that the marker is still bonded to the nanoparticle. Therefore, it is unclear whether you detect the nanoparticles or just the marker itself.

In contrast, nanodiamonds offer the chance to integrate the marker inside by embedding foreign atoms in the lattice of the nanocrystal. You then talk about so-called defects. The fact that it is possible to detect three different markers with different methods has already been demonstrated with macroscopic diamonds: fluorescent defects are visible with special microscopes; defects from unstable isotopes emit ionizing radiation that is visible in SPECT for example, and the embedding of isotopes that respond to external magnetic fields enables detection with magnetic resonance.

It makes sense that these marker options can also be transferred to nanodiamonds. If we succeed in this, you could detect nanodiamonds on virtually all relevant scales of biomedical research, ranging from the individual cell and its compartments all the way to organs without altering their surface and therefore their biochemical behavior. So far, this is not possible with any other nanoparticle.
Photo: Nanodiamond

During the production process, nanodiamonds are heated under pressure of less than 0.00001 mbar for 24 hours to 700°C; © RUBION – Ruhr University Bochum

How many nanodiamonds would you need for diagnostic purposes?

: It is almost impossible to predict this. On the one hand, if possible the markers should be so intensive that even an individual nanodiamond could be detected; on the other hand, an individual nanodiamond still does not deliver diagnostically usable information. However, when we talk about the absolute number of nanoparticles, we should generally remember how incredibly tiny these particles are. With today’s technology, you can produce nanodiamonds that are approximately five nanometers in size. If you assumed for simplicity’s sake that nanodiamonds have the shape of a cube, the number of nanodiamonds in a one-milliliter cube would already amount to a 24-digit number. The absolute number of nanodiamonds will be very high.

For which diseases would this method most likely be used?

: Our goal is not to be able to diagnose a specific disease, but to offer medicine a universal tool. As far as I know, there has not been any research on whether marked nanodiamonds prefer to penetrate a specific type of tissue without subsequent modification in the body.

Are additional features meant to be set up on the surface of nanodiamonds?

: That depends on what you are using the nanoparticles for. One obvious option is to functionalize the surface of nanodiamonds with specific antibodies. Multiple functionalizations with an antibody and a drug are also a possibility. Ultimately, nearly all previously conducted approaches with nanoparticles that are based on surface functionalization are also conceivable for nanodiamonds. If we succeed in transferring the marking processes from macroscopic diamonds to nanodiamonds, for the first time ever, nanodiamonds would offer the chance to track the application with imaging both on the cellular and the organ level. This in turn would make it possible to optimize individual therapy treatments and diagnostic procedures, to reduce side effects and to actually research new procedures.

Has this procedure already been tested in animal experiments?

: Nanodiamonds have already been embedded in the Caenorhabditis elegans nematode, which showed no unusual response after treatment. I also know of several current projects where nanodiamonds are being tested in vertebrates and mammals. However, these studies have not been completed and published yet, so that I don’t want to speculate on the results at this point.

1: Extracted from the song: Diamonds Are a Girl’s Best Friend by Leo Robin
Foto: Simone Ernst; Copyright: B. Frommann

© B. Frommann

The interview was conducted by Simone Ernst and translated by Elena O'Meara.