Developments in the biosynthesis of nanoparticles have increased significantly during
the last few years as a result of the growing interest in the unique properties displayed
by nanoparticles. These particles are extremely small in size and have a large surface
to volume ratio, giving them unique physical and chemical properties at this scale that
differs considerably from when they are used in larger form. These exceptional
properties are used in a wide variety of applications, ensuing nanotechnology to become
a multidisciplinary field. Research into application structure types are extended daily and
as a result, the next few years will be crucial as applications for nanomaterials in the
industry are most likely to be increased.
Gold nanoparticles is receiving more and more attention because of its wide variety of
uses in optical, electronic, magnetic, catalytic, and biomedical applications, but even
more due to them being the most stable of all the metal nanoparticles. Several methods
are used to produce these metal nanoparticles, but are mostly making use of toxic
chemicals in the synthesis protocol, which are harmful to the environment and human
health. To overcome this problem, researchers are making use of more âgreenerâ
alternatives through the use of biological systems and microorganisms in nanoscience
and nanotechnology. These microorganisms have unique potential in producing
nanoparticles that are environmentally friendly and display different shapes, sizes and
distributions. Among the different microorganisms used, bacteria have received the
most attention in the nanoparticle production process, but have not been as successful
as chemical synthesis to produce monodisperse noble metal nanoparticles.
In this study, successful gold reduction and nanoparticle formation with different shapes,
sizes and distribution was obtained; however, these particles were not monodisperse.
This was achieved with a thermostable protein of ± 70 kDa that was identified as an ABC
transporter, peptide-binding protein and which was purified from Thermus scotoductus
SA-01; an extremophile and thermophilic bacterium that was isolated from groundwater samples from Mponeng (a deep South African gold mine in the Witwatersrand
Supergroup operated by AngloGold Ashanti) at a depth of 3.2 km with ambient rock
temperature of 60ºC. The protein was expressed in Escherichia coli and Thermus
thermophilus HB27, a mesophilic and a thermophilic expression host respectively. It
was found that the expression host might have an influence on the way the protein is
folded and therefore influence nanoparticle formation. Expression studies was also done
on the protein that either included or excluded Histidine-Tags and a leader peptide, but it
was found that neither the His-Tags nor the leader peptide had any influence on the
nanoparticles produced.
Gold reduction and nanoparticle formation was obtained through reduction of a surface
exposed disulphide bond in the ABC transporter, peptide-binding protein, using sodium
dithionite as electron donor and reducing agent. In general it was found that
nanoparticle formation was dependant on environmental parameters but control of this
process was not complete. Chemical reduction did influence the nanoparticle formation
process in some instances, but overall it could be seen that the presence of the protein
played a significant role in slowing down the reaction rate, yielding a level of control over
the nanoparticles produced and ensuring a more environmentally friendly, biological
process for the production of gold nanoparticles.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-10192011-121457 |
| Date | 19 October 2011 |
| Creators | Erasmus, Mariana |
| Contributors | Prof J Albertyn, Prof E van Heerden |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-10192011-121457/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0023 seconds