Thousands of researchers are seeking ways to capture human health within a simple probe. Why? Every person is unique – in the personality as well as in terms of health. And the task of defining the healthy state at a populational level is just colossal. In the face of this, it is crucial to detect aberrations in health as soon as only possible, raising the alarm that a disease is sneaking into one’s body. Many diseases could be better coped with if we were alarmed earlier, as they only start developing. Especially cancer. This is where less invasive ways of disease detection come into play.

In a very inter-disciplinary team at the laser physics department of the LMU Munich, we believe to have made a step in this direction: We analyzed a fluid that connects all the organs – blood. The idea is familiar to anyone from medical check-ups, and it has recently been used for profiling with modern omics techniques. In our case, however, we exposed tiny amounts of blood to infrared light and captured the vibrations originating from the soluble biomolecules. In collaborative work with medical doctors from the LMU Comprehensive Pneumology Center, we set up a proof-of-principle clinical study to collect blood of individuals that were definitely known to have lung cancer, and in parallel from generally healthy, comparable individuals. We measured their blood samples with infrared spectroscopy. And finally - with quite high certainty - we succeeded to tell apart whether a person had lung cancer or not. From a mere drop of blood.

Eureka? Well, we want to go even further. While infrared fingerprints may distinguish lung cancer, they do not yet inform us about the individual blood components that make up the difference. Nevertheless, it would be good to know their identity to be able to further improve the method. This is what we demonstrated in a new study just published in Angewandte Chemie (DOI: 10.1002/anie.202103272). It is all about a combination of two techniques that are usually applied separately: mass spectrometry and infrared spectroscopy. The aim was to decode the actual chemical changes behind the previously “black box” infrared fingerprints of lung cancer. Now, with mass spectrometry of blood samples performed at the Max Planck Institute of Biochemistry in Munich, we identified a set of 12 proteins that account for the spectral signature of lung cancer, where early diagnostic markers are currently missing. All of these proteins were known since a long time. Now - like old dogs playing new tricks - the combinatorial protein signature that we defined turns a new page in diagnostic efforts. And this signature can be measured in a matter of minutes using infrared light!

So are we now one step closer to capturing disease and defining health? Certainly so. Especially as laser scientists at our department are engineering new ways of delivering ever shorter and more precise pulses of light for spectroscopic investigations. Metaphorically, this is like a magnifying lens that allows us to inspect the molecular zoo in our blood at once – in a snapshot. Finally, the results are of broader relevance for many disciplines, as one may generalize our findings to detection of other diseases that leave their traces in blood.

Yet, while we are working on new advances in capturing human health by shining light through drops of blood, we are bearing in mind the notion of Isaak Newton: “What we know is a drop, what we don’t know is an ocean.”.