Modern mass spectrometric techniques constitute an indispensable tool in biomedical research and clinical analytics. The research department Biomedical Mass Spectrometry is dedicated to the advancement of the two most important ionization methods for the mass spectrometric analysis of large biomolecules, Matrix-assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS), a technology that was introduced in Münster, and Electrospray Ionization Mass Spectrometry (ESI-MS). In our projects from the area of laser mass spectrometry, we develop, among others, novel postionization techniques for improvedMALDI imaging. mass spectrometry This still young technology enables visualization of the distributions of numerous biomolecules (in particular peptides, lipids, metabolites) in tissue sections at high lateral resolution. By introducing the so-called MALDI-2 technique, by which secondary MALDI-like ionization processes are initiated in the gas phase, we could recently improve the limits of detection of MALDI imaging MS for numerous biomolecules by two orders of magnitude and more. In this way the distribution of liposoluble vitamins e.g. could be visualized for the first time with a lateral resolution of about 10 micrometers. An illustration is given in a video, recorded on the occadion of the "Science Day" of the Medical Faculty.In current third-party funded projects we aim at improving the lateral resolution further to 1 - 2 micrometers and to chemically image single cells. In a closely related project, we work on improving quantitative imaging mass spectrometry in order to obtain absolute figures on the amount of substances within a tissue spot. We want to use the accomplished methodological advances to obtain a deeper insight into the role of signaling and receptor molecules during infection and inflammation processes. By recording a comprehensive chemical profile (metabolome) of microorganisms for example we hope to achieve a better understanding about the chemical communication of bacteria with their environment (e.g. within biofilms). In this way, novel approaches for preventing a contamination of medical surfaces such as those of catheters may be revealed. The surfaces of eukaryotic cells contain numerous glycosylated (i.e., sugar-decorated) molecules. These glycoconjugates play key roles in numerous biological processes like signaling and cell recognition and serve as receptors for bacteria, viruses, and other virulence factors. The structural characterization of glycoconjugates and their binding partners, and, moreover, the structural and thermodynamic analysis of their non-covalent interaction is essential for understanding receptor-ligand binding processes. The development of methods for qualitative and quantitative analysis of glycoconjugates (i.e., glycoproteins, glycolipids and free glycans) and application of these techniques for solving current biomedical research questions constitutes another major focus of our research. In these projects, we apply highly sensitive mass spectrometry, immunochemical, and chromatography methods and techniques. Among others, a Fourier transform-ion cyclotron resonance mass spectrometer (FT-ICR-MS) is used with ESI and other ionization sources such as desorption electrospray ionization enabling the analysis of surfaces. FT-ICR mass spectrometry is characterized by offering an extremely high mass resolving power, high mass accuracy, and means for applying different (multi-stage) fragmentation methods. In this way, the structure of even very complex glycoconjugates can be deciphered.