Single-molecule fluorescence can be used to image the dynamics of a cell. However, this technique has two major limitations: the current fluorescent labels are not optically stable, which means they can only be followed for a fraction of a second, and larger labels hinder the functioning of the cell. A research team under the leadership of Dr. John van Noort (LEI) proposes studying the cells with the aid of gold nanorods. They believe that this will resolve both of the aforementioned problems. The golden rods emit clear optical signals that do not flash or extinguish. And the rods can move throughout the cell without causing any damage, as they are not much bigger than a large protein.

The team is made up of researchers from various departments of the Cell Observatory of Leiden University. Van Noort: "In this project we will combine technical, physical, chemical and biological knowledge. One party knows a lot about spectroscopy, another about cell dynamics, whereas a third party has the chemical expertise needed to construct the gold particles. By consolidating our strengths we can tackle the most relevant challenges in cell biology and biophysics." According to Van Noort the new imaging technique will yield spectacular opportunities for biological physics.

The rods, measuring several tens of nanometres, can move freely throughout the cell and will be used to stain specific proteins. The nanorods are so clear that their position can be tracked to an accuracy of several nanometres for many tens of minutes. That makes it possible to follow individual molecules in a cell over a long period of time and consequently to map the processes that these undergo at a molecular scale. It is even possible to pick up and move the rods using strongly focussed light. How these techniques can be applied in the cell will be investigated during this FOM Programme.