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


Photo: Dr. Patrick Happel

Dr. Patrick Happel; © RUB

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.

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.

How are the lattice defects embedded in the diamonds?

: There are two known options for fluorescent defects: on the one hand, you can already specifically embed impurities during the production process, which lead to lattice defects. On the other hand, defects can also be embedded later through irradiation with ions in ion accelerators. Within the scope of the current VolkswagenStiftung sponsored project "Functionalized nanodiamonds for biomedical research and therapy", we are investigating whether and to what extent similar methods can be used to also embed detectable markers in nanodiamonds in SPECT or MRI.
Photo: Nanodiamand

Nanodiamonds with fluorescent lattice defects (shown in red) in cells from the HeLa cell line (marked with a white border); © RUBION – Ruhr University Bochum

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.

Do the well-known imaging procedures still need to be adapted or is any device able to detect the signals?

: Technically the procedures don’t need to be adapted. Our goal is to be able to detect the nanoparticle with the currently available technology. Of course, there might be devices where individual components need to be retrofitted.

When do you anticipate the procedure to be field ready?

: We are currently working on developing the basic tool for medical application. If we succeed, the devil will be in the details for every single potential application. Unfortunately, this is why a realistic prediction is impossible.

Foto: Simone Ernst; Copyright: B. Frommann

© B. Frommann

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