guest ::
%0 Thesis %A Wang, Huihui %T Enzymatic synthesis of silicon dioxide capsules with tunable size, morphology and functionality %I Aachen, Techn. Hochsch. %V Dissertation %C Aachen %M RWTH-2015-04554 %D 2016 %Z Veröffentlicht auf dem Publikationsserver der RWTH Aachen University 2016 %Z Aachen, Techn. Hochsch., Diss., 2015 %X In the process of biomineralization, the formation of the mineral phase and the final structure depend on involved proteins because of their catalytic activities, specific sizes and colloidal behaviors. This natural synthetic pathway inspired this work to use similar approaches which lead to the formation of various synthetic protein-silica hybrid structures.In this research work SiO2 micro-/ nanocapsules were enzymatically synthesized, using Pickering emulsions as template for capsules. Recombinant silicatein (a natural protein specific for the Biosilicification), Lysozyme (a natural hydrolase with a similar active site as silicatein) and a synthetic polymer PNIPAAm (an analogue of the enzyme) were applied as enzyme / catalyst. The special feature of this method is that the enzymes are not only enzymatically active but also interfacially active: they self-assemble at the interfaces and form oil-in-water emulsion (SiO2 precursor as an oil-phase and enzyme solution as aqueous phase) and at the same time catalyze the condensation of the precursor at the interfaces.Hybrid capsules with tunable size, shell-thicknesses and surface morphology were achieved by using different emulsification methods (mechanical or ultrasonic mixing), different ratio of precursor to protein in solution or by changing the buffer type and composition with the addition of various salts or ionic surfactants. Furthermore, a one-step approach to introduce additional reactivity in the form of primary amine-functionalities on the capsule surface was performed, which makes the system more versatile for possible post-modifications. This research offers insights into the biomimetic mineralization processes using native protein functions and bio-inspired systems. The environmentally friendly straightforward synthesis approach combining the catalytic and interfacial activities of proteins (or analogues of proteins) displays high versatility for the formation of hybrid silica capsules with tunable size, morphology and functionality. This work also opens new pathways for the synthesis of novel silica materials with high efficiency. %F PUB:(DE-HGF)11 %9 Dissertation / PhD Thesis %R 10.18154/RWTH-2015-04554 %U https://publications.rwth-aachen.de/record/482000