From nature for nature – bioinsipred nanocomposite materials for environmental technology

Microorganisms like bacteria developed during evolution highly effective mechanisms and structures to survive at the most forbidding, uninviting places on Earth. One example, intensively studied at the Institute of Radiochemistry of the Forschungszentrum Dresden-Rossendorf, is the binding of heavy metals and actinides by cell surface proteins of uranium mining waste pile isolates. The so called surface layer (S-layer) proteins prevent the uptake and any sustainable damage of the cell by toxic and/or radioactive metals. The S-layers itself form highly ordered and mono-molecular envelopes around bacterial and archaeal cells. Noteworthy is their ability to self-assemble in suspension, on surfaces and at interfaces. Furthermore S-layers of different bacteria are able to fulfil different functions and thus may act as immobilization matrix for exoenzymes, as molecular sieve, as ion and molecule trap or they protect the cell from being affected by the immune defence of host organism, by other bacteria or by lytic enzymes. By combining these unique features of S-layer proteins, smart coatings on many different surface can be realized. Currently at the Institute of Radiochemistry, S-layer based functional coatings are under development for the production of (photo)catalytic active materials, metal selective filters or highly specific biosensors. Therefore possible applications are the elimination of pharmaceuticals and germs, the detoxification of metals, the removal of toxic metals, the recovery of noble metals or the detection of pharmaceuticals and other organic matter in water. Additionally, combinations of functionalities are possible using a layer-by-layer technique, offering a wide field for the development of new nanostructured biocomposites for environmental technology.