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Abstract

This thesis presents a study of different nanoscale functional properties of Mo6S9-XIx nanowires and
demonstrates a straight-forward functionalization route based on self-assembly. In order to ascertain their
basic functional properties, studies of dispersion and electromobility under different conditions were
performed. It was found that the nanowire bundles, due to their large diameters and long lengths, cannot
travel through electrophoresis gel like DNA, CNTs and other familiar entities. The gel pores are too small,
thus the individual thicker Mo6S9-XIx bundles and especially the agglomerated networks and meshes
become trapped in the wall of the gel pockets, blocking the pores completely. Despite the fact that the
nanowires exhibited no travel through the gel, their definite movement towards the positive wall of the gel
pocket revealed their negative charge in aqueous solution. Dielectrophoresis was used to manipulate
Mo6S9-XIx nanowires and to construct point-field emitters. Mo6S9-XIx emitters proved to be comparable in
performance, durability and current stability to SWCNTs emitters.
Dispersability of Mo6S9-XIx nanowires in different pH has been tested by performing sedimentation
studies and microscopic characterization. It was found that decreasing the solution pH also resulted in
significant diameter reduction of the nanowires. However, the quantity of the sediments seemed to increase
as well, implying disintegration of structures. The most stable dispersion showed a neutral pH.
Armed with the results from dispersion studies, a functionalization of Mo6S9-XIx nanowires in aqueous
solution with different (bio) molecules was obtained, and nanowires with gold colloids in two, three and
even in multi-terminal connectors were functionalized. The bond between the nanowires and the gold
colloids appears to be a covalent bond facilitated by the compatible distances between Au-Au and the Mo-
Mo atoms in the nanowire. In the next step, the attachment of thyroglobulin and green fluorescent protein
to two different types of nanowires, as-grown nanowires and sulfonated nanowires was successfully
performed. The sulfonated nanowires were seen to be decorated over their entire surface with protein,
whereas in the case of as-grown material the proteins connected to the ends of the nanowires. Topographic
and force-curve AFM measurements enabled the determination of the fingerprints of Mo6S9-XIx nanowires,
proteins and substrates, and made it possible to distinguish between different types of nanostructures which
self-assemble in solution.