Identifikation und Charakterisierung von Zirkoniumdioxid-affinen Peptiden zur Mineralisation von Zirkoniumdioxid
Final Report Abstract
Biomineralization processes for the generation of materials is a highly recognized multidisciplinary research field. To include technical relevant inorganic materials in the synthesis using biomineralization processes, specific organic effector molecules have to be identified which control the mineralization process. In this project the peptides as biological effector molecules for the biomineralization of ZrO2 were identified and investigated. The identified peptides were further applied for the bioinspired mineralization of ZrO2-based materials form aqueous precursor solutions. In the scope of this project questions concerning the organic-inorganic interaction and the influence of the peptides on material synthesis and properties were addressed. Mainly, the following topics were investigated. The target material which was used for the isolation of peptides from a random peptide library by phage display was characterized not only in terms of elemental composition, crystal structure, and surface roughness, but also for the zeta potential which plays a major role for the binding of peptides. Commercially available, single crystalline ZrO2 substrates are synthesized with Y2O3 for stabilizing the cubic crystal structure. To elucidate the influence of Y2O3 on the selection of peptides pure ZrO2, Y2O3, and yttria-stabilized zirconia (YSZ) powders were included as target substrates for phage display. In this connection the use of powder vs. single crystal substrates was investigated. The peptides isoelectric point (pI) was correlated with the target substrates surface charge. The isolated ZrO2-binding peptides were computationally analyzed with regard of the amino acid composition in order to the identification of a binding motive based on conserved peptide sequences. Since the peptide sequences were too diverse, no consensus sequence could be deduced. To evaluate the binding quality of individual ZrO2-binding peptides, which were selected based on enriched amino acid residues, an assay based on individual phage clones was establish to evaluate the binding strength of the peptides. A biomineralization procedure in which the inorganic-binding peptides were integrated was established. Exclusively, aqueous reaction solutions based on different Zr-containing salts were tested and the influence of the peptide on the biomineralization process was determined. In this context the interaction of inorganic-binding peptide within the inorganic phase was of high interest. The question whether the peptides were integrated or adsorbed on biomineralized particles was answered. Additionally, since natural hybrid-biominerals show material properties which deviate from their inorganic counterparts, the photoluminescence properties of the bioinspired zirconia were analyzed and showed photoluminescence which was not present in the inorganic material only. The ZrO2 binding peptides allow the tuning of the optoelectronic properties by the generation of defined organic-inorganic interfaces.
Publications
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Generation of luminescence in biomineralized zirconia by zirconia-binding peptides. CrystEngComm, 2015, 17, 1783 - 1790
D. Rothenstein, D. Shopova-Gospodinova, G. Bakradze, L. P. H. Jeurgens and J. Bill
