Free radicals play a role in several processes in healthy individuals including how we defend ourselfes against bacteria or viruses, how cells talk to one another or how our cells age. But they are also present, when a cell responds to stress for instance when a cancer cell is killed by a drug. However, depite their importance it is difficult for the state of the art to measure free radical generation since they are short lived, reactive and low in abundance. In the ERC project we used quantum sensing to measure these free radicals in living cells. The new technology allows us to measure in which organelles free radicals are built during a stress response. By measuring how these special diamonds change their brightness we can extract information that is similar to an MRI. With the difference, that we can see much smaller signals. Using this method we were able to differentiate between young and old cells. This was demonstrated in yeast cells which function as an ageing model. Since our method is based on nanodiamond particles which need to enter the cells, we first optimized particle uptake into yeast cells. While this is trivial for mammalian cells which readily ingest particles, uptake is challenging in yeast since they have a thick cell wall.
We were able to quantify and compare the free radical load in young and old cells. We also investigated different mutant strains which are different in their longevity and found clear differences. Interestingly, mutant cells do not necessarily have a lower radical load but respond to stress differently than wild type cells. Further, we were able to age cells under different conditions which is interesting for ageing research.
We were also able to measure how much of these radicals our immune cells generate when we are stimulating them. More specifically, we were able to target nanodiamonds to specific locations as for instance the mitochondria and measure specifically at these specific organelles.
The versatile technique has since been used for measurements in patient samples, tissues and body fluid. Recently, the startup company QTsense has been founded to exploit the knowledge generated in this project.
