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27. January 2020 | by Thorsten Naeser

Scientists at the Laboratory for Attosecond Physics have developed a unique laser technology for the analysis of the molecular composition of biological samples. Could a combination of laser sciences and molecular detection be cracking the limits of molecular sensing?

The combination of molecules found in body fluids such as blood plasma is unique to each individual, and the composition of this ‘brew’ can provide information on an organism’s state of health. The problem lies in learning to decipher the information it contains. Complete molecular characterization has been impossible up to now, because our instruments are not sensitive enough to identify and quantify the entire range of chemical compounds present. But this goal has now moved a step closer to realization. Researchers at Laboratory for Attosecond Physics (LAP), which is run jointly by the Max Planck Institute for Quantum Optics (MPQ) and Munich‘s Ludwig-Maximilian University (LMU), in cooperation with scientists of the King Saud University and the Hungarian Center for Molecular Fingerprinting have developed a laser-based system – the first of its kind in the world – that is capable of detecting minimal variations in the chemical make-up of biological fluids across the whole spectrum of molecular species.

At the biochemical level, organisms can be thought of as complex collections of different species of molecules. In the course of their metabolism, biological cells synthesize chemical compounds, and modify them in multifarious ways. Many of these products are released into the intercellular medium and accumulate in body fluids like the blood. One major aim of biomedical research is to understand what these immensely complex mixtures of molecules can tell us about the state of the organism concerned. All differentiated cell types contribute to this ‘soup’. But precancerous and malignant cells add their own specific molecular markers – and these provide the first indications of the presence of tumour cells in the body. So far, however, very few of these indicator molecules have been identified, and those that are known appear in minuscule amounts in biological samples. This makes them extremely difficult to detect. It is assumed that many of the most informative molecular signatures comprise combinations of compounds that belong to all the various types of molecules found in cells – proteins, sugars, fats and their diverse derivatives. In order to define them, a single analytical method that is versatile and sensitive enough to detect and measure the levels of all of them is needed.

An interdisciplinary team led by Prof. Ferenc Krausz has now built a new laser-based system that is specifically designed for this purpose. The group is based at the Laboratory for Attoseond Physics (LAP), which is run jointly by the Max Planck Institute for Quantum Optics (MPQ) and Munich‘s Ludwig-Maximilian University (LMU), and it includes physicists, biologists and data scientists. This system enables one to obtain chemical fingerprints in the form of spectra of infrared light, which reveal the molecular compositions of samples of all sorts, including samples of biological origin. The technique offers unprecedented sensitivity and can be used for all known classes of biomolecules.