The research field "Multiscale Bio-Systems" involves several levels of (self-)organization in biological and bio-inspired systems. These different levels are reflected by the four core areas pursued within the School. The first two core areas focus on molecular processes: Core area 1 elucidates the specific interactions of biopolymers while core area 2 studies molecular processes induced by light. The remaining two core areas 3 and 4 address cell-like as well as tissue-like systems and processes. The long-term goal is to understand, in a quantitative manner, how the latter processes emerge from the physico-chemical interactions at the molecular scale.
Core Area 1: Molecular Recognition of Biopolymers
Research in this core area starts with the synthesis of biopolymers, primarily carbohydrates and proteins, with a well-defined molecular architecture. The mutual interactions of these molecules are then studied by anchoring them to nanoparticles, solid surfaces, lipid monolayers or bilayers. In this way, they become amenable to experimental methods that probe these surfaces with high spatial and/or temporal resolution. These structural methods are complemented by kinetic and thermodynamic measurements as well as by theoretical modelling based on molecular dynamics simulations and Markovian analysis. One focus is provided by the interactions between carbohydrates and proteins which are multivalent in nature and play a crucial role in many biological processes.
Core Area 2: Photo-induced Molecular Processes
Two photo-induced processes are studied in this core area: hydrogen production by photoinduced cleavage of water and photo-induced conformational changes of molecular assemblies. An efficient and green method to produce hydrogen from water and sunlight would provide a very appealing solution to the human demand for energy. The main challenge for such a process is to find appropriate catalysts. Two very efficient catalysts are provided by polymeric carbon nitride and by the enzyme Fe-Fe hydrogenase. A relatively simple class of molecules that undergo photo-induced conformational changes is provided by azobenzene derivatives.These molecules can be anchored to lipid membranes and vesicles. Another photo-switchable biosystem is provided by optimized complexes of DNA and photosensitive surfactants. Likewise, the association and dissocation of certain proteins (phytochromes and cryptochromes) can also be controlled by light.
Core Area 3: Cell-like Systems and Processes
Cells are the basic and universal building blocks of life. From a physico-chemical point of view, cells are micro-compartments that contain a large number of different biomolecules, interacting with each other in multiple ways. The resulting (intra)cellular processes can be studied, to some extent, using biomimetic micro-compartments such as lipid vesicles. The latter compartments are multiresponsive and mimic several functionalities. One basic functionality is the confinement of biomolecules to a certain spatial region, thereby preventing their escape and dilution into the environment. In vivo, these molecules form complex reaction networks which fulfill many different functions. Some enzymatic networks, for example, are responsible for the chemical modification of certain types of biomolecules while others control the growth of biominerals within intracellular vesicles.
Core Area 4: Tissue-like Systems and Processes
When cells assemble into tissue and synthesize extracellular matrix (ECM), new properties emerge. However, the relation between these properties and the architecture of the ECM as well as the cell-ECM relations are poorly understood. In particular, physical interactions based on mechanical forces, e.g., generated by molecular motors or by osmotic gradients, are known to play a decisive role for tissue growth and regeneration, as well as generation and modification of form. An improved understanding of these relationships is important for both biomedical application and bio-inspired materials development.