We aim to understand the mechanisms of assembly and function of soft biological interfaces, to advance knowledge and for applications in the life sciences. We are particularly interested in extracellular matrices that are rich in glycans; these microscopic hydrogel-like assemblies are important regulators of cell function and inter-cellular communication. Another main object of our research is the nuclear pore permeability barrier, a nanoscopic meshwork of intrinsically disordered proteins that makes macromolecular transport between the cytosol and nucleus of cells selective and is crucial for orderly gene expression. Resolving how these systems work provides new approaches to prevention, diagnosis and treat disease, and inspiration for the design of new functional materials. To understand how biological functions emerge from the assembly and dynamic reorganization of biomolecules, we adopt a multidisciplinary approach that combines living cells and tissues with well-controlled models of tunable complexity. Exploiting surface science and engineering tools, we tailor-make model systems by the directed self-assembly of purified components on solid supports. For the quantitative analysis of these biomimetic systems, we develop a toolbox of physico-chemical in situ analysis techniques including quartz crystal microbalance (QCM-D), atomic force microscopy (AFM), spectroscopic ellipsometry (SE) and advanced optical microscopy methods. We use concepts from biological and soft matter physics to rationalize the properties of soft biological matter, and collaborate closely with biochemists and biologists to integrate our bottom-up biosynthetic approach with work at the levels of molecules, cells and living organisms.