The basis for the design of micro- and nanostructured, multifunctional materials is molecular organization. It encompasses multi-component materials as well the hierarchical, geometric structure of molded bodies. In our “Micro-/Nanotechnology” department, we pursue experimental approaches in the areas of manufacturing processes and physical characterizations as well as concepts for predicting functions using multiscale models. Structural function, movement and adaptivity through the reinforcement of nano-effects at the macroscopic level thereby facilitate, among other aspects, multifunctional, shape-changing or biointeractive materials.
Our generic approach aims to create bioinstructive cell culture substrates, active implants and artificial muscles simply by varying geometry and structural function with a limited number of materials.
Cross section of a porous microparticle (SEM-image) Photo: Hereon
We are engaged in the processing and development of new multifunctional polymer materials with adjustable properties for use in biomedicine. One focus is on polymer processing technologies based on so-called integrated processes that combine design and functionalization or modification. The basic research on the structure-property relationship of polymers at different length scales from molecule to component is of particular interest to our department.
Another focus is the design of material surfaces in order to control the interaction with cells, proteins and physiological fluids. In this context we apply in particular micro-and nanostructures and molecular polymer layers and explore these polymeric surfaces via microscopic techniques in terms of their structure, chemical composition and mechanical properties.
A key step towards the application of polymeric biomaterials in medicine or medical technology is their processing into a wide variety of devices. We therefore concern ourselves with various polymer processing technologies starting from the polymer melt (e.g. extrusion, injection molding) or the polymer solution (e.g. electrospinning). On the one hand this includes the processing of polymers, blends and composites thereof to simple semi-finished products such as films, monofilaments or tubes and the manufacture of porous foam structures or microparticles as well as the production of very complex components and demonstrators consisting of several materials under cleanroom conditions.
In addition to the processing of plastics we develop methods for modification of polymer components with additional new features, such as shape-memory effects. Upon selection of thermo-mechanical treatments, we can control whether a plastic can memorize one or more shapes, the temperature at which the change in shape takes place and whether it should be reversible or not. In this context, the basic research into the structure-property relationships of polymers on different length scales of the molecular structure to the component is of particular importance for us.
The nature of biomaterial surfaces is of crucial importance for the diverse interactions with proteins, physiological fluids, cells and tissues. In this respect, great versatility is also required in the design and modification of such surfaces. In this context, we pursue to control the adhesion and differentiation of various cell types the approach with the help of targeted micro-and nanoscale patterning of biomaterial surfaces. For structuring surfaces, we use template-based techniques as well as electrospinning approaches. As a technique for the chemical surface modification we apply plasma treatment, which allows the deposition of thin layers on biomaterials.
Another focus is the characterization of micro-and nanostructured surfaces in our department. Here, we apply scanning electron microscopy (SEM), optical profilometry, and atomic force microscopy (AFM) for the analysis of surface structures. Information about the elemental composition of the top 10 nm of the surface as well as the chemical bonding state of these elements is provided by photoelectron spectroscopy (XPS). Particularly important in this context are studies in aqueous environments by means of contact angle and streaming potential measurements and micromechanical studies of biomaterials using AFM.