Hybrid nano titania: molecular formation mechanisms and applications in nanotechnology.

Nanomaterials are defined as materials with one dimension smaller than 100 nm. At this size, exotic properties start to emerge, making them interesting for a wide range of applications including catalysis, electronics, theranostics, and “smart materials”. Particularly engineered metal oxide nanoparticles have found advanced applications in medical therapy and catalysis. Because of the small size and required homogeneity of these materials, bottom-up synthesis starting from molecular precursors is often the preferred way of production. The present work was initiated with the main purpose to bring insight in the whole chain in materials design and application – from precursor chemistry in the synthesis to physical chemical and biological characteristics of the resulting nanomaterials. It is thus an interdisciplinary project, covering the fields of both chemistry and biology. The chemical part presents synthesis, self-assembly, and chemical characterization of titania nanopowders, hollow titania spheres, and nanotitania-nanocellulose hybrid materials. The biological part primarily evaluates titania-nanocellulose hybrid materials for drug delivery applications using in vitro bacterial cultures and immunological (coagulation-related) responses in human whole blood. Not unexpectedly, titania-nanocellulose hybrids generally induced strong coagulation via the contact activation system. An extensive part of the thesis is dedicated to the solution behavior, stability, and transformation of heteroleptic titanium oxo-alkoxides into nanotitania, using a variety of characterization techniques. The observations support the MTSAL mechanism for formation of metal oxide nanoparticles. No hydrolytic stability, however, from ligandmodification of titanium (oxo-) alkoxides could be observed.