Catching breath: Targeting exhaled breath condensate (EBC) via gas-phase electrophoresis (nES GEMMA instrumentation)
V. U. Weiss, Vienna/AUT, Marija Zora Mišković, Zagreb/CRO, Petr Kuban, Brno/CZE, Sara Lado, Vienna/AUT, Christoph Steininger, Vienna/AUT, M. Marchetti-Deschmann, Vienna/AUT
Assoc. Prof. Dr. Victor U. Weiss, TU Wien, Getreidemarkt 9/164, 1060 Vienna/AUT
Human breath analysis is an attractive alternative strategy for non-invasive retrieval of representative, unbiased samples directly from the lung of a patient. In such a way, information on the health status of a person can be obtained. Significant effort has been put e.g. into volatile organic compounds (VOCs) that show characteristic patterns in lung cancer-related breath samples. Also, VOC analysis via GC-MS has been lately used for SARS-CoV-2 diagnostics.
Gas-phase electrophoresis on a nano electrospray gas-phase electrophoretic mobility molecular analyzer (nES GEMMA) enables the separation and detection of (bio-)material in the nanometer size scale. [1] Analytes are electrosprayed from a liquid solution, followed by drying of droplets and concomitant charge equilibration. Subsequently, analytes are separated according to their surface-dry particle size in a high laminar sheath flow of particle free air and a tunable electric field applied in an orthogonal direction. Detection yields a spectrum of a corresponding sample relating particle size and respective number values. Based on our previous experience with the analysis of proteins, extracellular vesicles, viruses and virus-like particles we therefore reasoned that such an instrument is also capable to contribute to the characterization of particles in exhaled air (PEx), in particular in exhaled breath condensate (EBC).
Indeed, by applying EBC samples to gas-phase electrophoresis we were successful in obtaining corresponding spectra. For one donor, these spectra remained more or less constant over time (different time points of EBC collection). Low sample conductivity made as stable as possible nES conditions in terms of recorded current values a necessary prerequisite for data interpretation. Expanding our sampling strategy to more donors yielded spectra, some of which differed between individual donors and could be clustered via hierarchical cluster analysis. The overall biological and clinical relevance of recorded spectra will have to be targeted in a follow-up study. Likewise, this follow-up study will have to focus on clearly standardized collection, sample storage and measurement conditions.
Experiments presented in this study indicate that PEx detected during our experiments corresponds to unspecific aggregates. Particle collection together with further MALDI MS analysis will help in the future to deepen our knowledge on PEx.
Literature:
[1] S. L. Kaufman, Anal. Chem., 1996, 68, 11.
