Scientists at Johannes Gutenberg University Mainz (JGU) in Germany have developed a new method of observing individual proteins.

Detailed knowledge of the dynamics of proteins is necessary to understand the related biological processes that occur on the molecular level.

To date, this information has been obtained by labeling proteins with fluorescent substances, but this changes the proteins under investigation and thus influences the biological processes that are to be observed.

“Our method allows live tracking of individual proteins without having to label them first,” explains Professor Carsten Sönnichsen of the Institute of Physical Chemistry at JGU.

The method uses plasmonic gold nanoparticles, which serve as glowing nanoantennas that, when they detect individual unlabeled proteins, slightly change their frequency (color). These tiny color changes can be observed using the technique developed in Mainz.

It is now possible to precisely observe the dynamics of a protein molecule down to the millisecond, says Sönnichsen.

The opportunity to detect individual protein molecules also allows for tracking the fluctuation of protein population densities and observe protein adsorption processes in real time. “We can see how molecules move, how they dock at particular locations, and how they fold — this has given us a window into the molecular world,” explains Dr. Irene Ament, a member of Sönnichsen’s group.

This new technology may prove to be useful not only in chemistry but also in medicine and biology.

Ref.: I. Ament, et al., Single Unlabeled Protein Detection on Individual Plasmonic Nanoparticles, Nano Letters, 12:2, 1092-1095, 2012; [DOI:10.1021/nl204496g]