Bioinspired oxide ceramics

Oxide ceramics exhibit a broad field of application in modern advanced technologies due to their electrical, optical and mechanical performance. Because of their properties modern oxide ceramics contribute to the evolution of new fields of technology.
 The synthesis of those advanced ceramics needs elaborated manufacturing routes, which involve both complex process engineering and extreme reaction conditions. This results in constraints or even the impossibility to synthesize complex, multifunctional materials.
 Therefore, the search for low-temperature synthesis processes is currently a main goal in materials science research.
 Nature provides amazing examples of Biomineralization. By means of biomineralization organic-inorganic hybrid materials with remarkable functional properties are synthesized with apparently little effort under ambient conditions. For example, this is demonstrated by the remarkable mechanical performance of nacre (mother of pearl). Although, nature did not evolve concepts for technical relevant oxide ceramics, biomineral structures seems to be a suitable starting point to engineer synthesis routes for oxide ceramics in vitro and possibly by means of microorganisms in vivo.

 Synthesis of functional materials by microorganisms
 Biomineralization processes in some model organisms are investigated in detail, focusing the protein- and polysaccharide-mediated mineralization processes. Model organisms will be selected from algae and bacteria. We are aiming at the in vivo integration of non-biogenic elements in biominerals by microorganisms in the course of biomineralization processes. Furthermore, biomineralization relevant proteins should be isolated and corresponding genes should be identified and cloned.

 Templating biomineralization with bioorganic molecules and structures
 Biomineralization proteins are applied to initiate the in vitro deposition of oxide ceramics from aqueous solutions. Hence, the identified biomineralization proteins from microorganisms are added to mineralization reactions.
 Biomineralization relevant domains of the proteins, like mineral binding stretches, should be identified by means of molecular modelling (Working package 4). The optimization of these domains for the binding of non-biogenic elements is done using molecular genetic techniques.

 Characterization and Properties
 Natural biominerals as well as in vitro and in vivo synthesized bioinspired materials is analysed concerning structure and elemental composition. The crystalline structure is characterized by using X-ray diffraction (XRD). The mineral composition and morphology of the materials can be examined under different types of electron microscopy. Furthermore, investigations using atomic force microscopy can be done.
 The main focus is on the correlation of the structure, the chemical composition and the mechanical properties. Mainly, strength, hardness, Young`s modulus, fracture toughness, and scratch resistance are investigated.

 Modelling of interactions at organic-inorganic interfaces
A sequence and structural database of proteins involved in biomineralization processes is generated based on results form this research project and literature data. Molecular modelling aims at the identification of essential amino acids within a protein, which are necessary for the biomineralization process.  Upon these data peptide sequences are generated which reveal an optimized binding affinity to oxide ceramics promoting the synthesis of these materials.
 The data of molecular modelling are pass over to continuum mechanical modelling. Here the mechanical performances of the materials are modelled to optimize the systems, considering the influence of interfaces under mechanical load.