Self-assembled peptide template directed synthesis of one-dimensional inorganic nanostructures and their applications
Author(s)
Advisor
Güler, Mustafa ÖzgürDate
2012Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
Engineering at the nano scale has been an active area of science and technology
over the last decade. Inspired by nature, synthesis of functional inorganic materials
using synthetic organic templates constitutes the theme of this thesis. Developing
organic template directed synthesis approach for inorganic nanomaterial synthesis
was aimed. For this purpose, an amyloid like peptide sequence which is capable of
self-assembling into nanofibers in convenient conditions was designed and decorated
with functional groups showing relatively high affinity to special inorganic ions,
which are presented at the periphery of the one-dimensional peptide nanofiber. These
chemical groups facilitated the deposition of targeted inorganic monomers onto the
nanofibers yielding one-dimensional organic-inorganic core-shell nanostructures. The physical and chemical properties of the synthesized peptide nanofibers and
inorganic nanostructures were characterized using both qualitative and quantitative
methods.
First, silica nanotubes were obtained by silica mineralization around these peptide
nanofiber templates for the construction of sensors for explosives. The fluorescence
dye was used to coat the silica nanotubes to detect explosive vapor. The surface of
the silica nanotubes were porous enough to adsorb more dye compared to the silica
nanoparticles and silica film, and causes faster fluorescence quenching in the
presence of explosives like trinitrotoluene and dinitrotoluene. The silica nanotubes
which synthesized with this peptide nanofiber templates can be used in catalysis and
sensors in which high surface area is advantageous. In the second part of the thesis,
titanium dioxide nanotubes were obtained from titania mineralization. They are wellknown
with their fascinating properties as a result of the one-dimensional
nanostructure, such as more efficient electron transfer and less electron-hole
recombination. The sufficient photoactivity of titanium dioxide makes them suitable
materials for Dye-Sensitized Solar-Cell construction. It is demonstrated that the
peptide nanofiber templated titanium dioxide nanotubes have more than two times
more efficiency compared to template-free synthesized titanium dioxide particles.
Finally, designed peptide sequence was conducted to a multi-step seeding mediated
growth method for gold mineralization around peptide nanofibers. The gold-peptide
hybrid nanostructures with different packing characteristics and sizes were
synthesized and fully characterized. Further, it was demonstrated that the dry film of
these nanostructures showed a resistive switching dominant conductivity, due to the nanogaps in between gold nanoparticles as a result of particle alignment driven by
the peptide nanofiber.
The results obtained in this thesis encourage use of a new “bottom-up” synthesis
approach. Specially designed peptides with desired properties and functional groups
were synthesized and peptide nanofibers formed were further used as templates for
inorganic mineralization. Not only it is possible to synthesis high amount of
nanostructure with this approach, but also formed one-dimensional nanostructures
show advance functionalities used in several applications as a part of the thesis
scope. This methodology is suitable for many metals and metal oxide based
applications.
Keywords
Biomimetic mineralizationNanomaterials
Peptide
Self-assembly
One-Dimensional Nanostructures
Template Directed Synthesis