Bioinspred hybrid nanomaterials based on self-assembling proteins

Many 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 (figure 1) bind toxic metals and metalloids and thusly protect the cells from being damaged by these elements and their compounds. On other cells, S-layers 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 defense of host organism, by other bacteria or by lytic enzymes. These properties makes S-layer, together with their capability to self-assemble in suspension, on surfaces and at interfaces, very interesting building blocks for the construction of new bioinspired nanomaterials for different technical applications. Using the two-dimensional protein arrays, different kinds of surfaces can be nanostructured and multiple functionalized by a layer-by-layer technique. This interdisdisciplinary approach allows the design of novel bio-inorganic hybrid materials. Currently under development are three kinds of materials, namely metal filters, nanocatalysts and sensors. Regarding metal filters the aim is the development of selective materials for the removal of toxic metals and metalloids or the recovery of precious metals. In the case of nanocatalysts, the research is focused on the development of highly efficient catalysts or photocatalysts on the basis of immobilized and regular arranged metal or metal oxide nanoparticles for organic synthesis or the elimination of organic pollutants. S-layer based biosensors were under development to detect chemicals or pharmaceuticals by combining highly specific receptors like aptamers with stable fluorescence dyes.