Van Heerden, E.Albertyn, J.Erasmus, Mariana2015-09-012015-09-012010-052010-052010-05http://hdl.handle.net/11660/1110English: 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 “greener” 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.Afrikaans: Ontwikkelings in die biosintese van nanopartikels het gedurende die laaste paar jaar aansienlik verhoog as gevolg van die toenemende belangstelling in die unieke eienskappe van nanopartikels. Hierdie partikels is uitsonderlik klein en het ‘n groot oppervlakte tot volume verhouding. Op hierdie skaal gee dit aan hulle unieke fiesiese en chemiese eienskappe wat, aansienlik verskil van die gebruik daarvan in groter vorme. Hierdie uitsonderlike eienskappe word in ‘n wye verskeidenheid toepassings gebruik wat veroorsaak het dat nanotegnologie ‘n multidissiplinêre veld geword het. Ondersoek na toepassing-struktuur-tipes word daagliks uitgebrei, en as gevolg daarvan, sal die volgende paar jaar krities wees soos wat toepassings in die nanomateriaalbedryf waarskynlik behoort toe te neem. Goud nanopartikels ontvang meer en meer aandag as gevolg van die wye verskeidenheid van gebruike in optiese, elektroniese, magnetiese, katalitiese, en biomediese toepassings, maar veral omdat hulle die mees stabielste van al die metaal nanopartikels is. Verskeie metodes word gebruik om die metaal nanopartikels te produseer, maar giftige chemikalieë word meestal gebruik in die produksie proses wat skadelik is vir die omgewing en vir menslike gesondheid. Om hierdie probleem te oorkom maak navorsers gebruik van meer "groener" alternatiewe deur die gebruik van biologiese sisteme en mikroörganismes in die nanowetenskap en nanotegnologie. Hierdie mikroörganismes het unieke potensiaal in die vervaardiging van nanopartikels wat omgewingsvriendelik is en lei tot verskillende vorms, groottes en verspreiding van nanopartikels. Tussen die verskillende mikro-organismes wat gebruik word, ontvang bakterieë die meeste aandag in die nanopartikel produksie proses, maar is nie so suksesvol soos chemiese sintese in die produsering van egalig verspreide edel metaal nanopartikels. In hierdie studie was suksesvolle goud reduksie en nanopartikel vorming met verskillende vorms, groottes en verspreiding verkry, maar hierdie deeltjies is nie egalig Opsomming 203 verspreid nie. Dit is bereik met ‘n termostabiele proteïen van ± 70 kDa wat as ‘n ABCvervoerder- peptied-bindings-proteïen geïdentifiseer is. Hierdie proteïen is gesuiwer vanuit Thermus scotoductus SA-01, ‘n ekstremofiele en termofiele bakterie wat in grondwater monsters van Mponeng (‘n diep Suid-Afrikaanse goudmyn aan die Witwatersrand Supergroep, beheer deur AngloGold Ashanti) op ‘n diepte van 3,2 km met omringende rots temperatuur van 60ºC geïsoleer is. Die proteïen is uitgedruk in Escherichia coli en Thermus thermophilus HB27, ‘n mesofieliese en ‘n termofieliese uitdrukkingsgasheer onderskeidelik. Dit is bevind dat die uitdrukkingsgasheer ‘n invloed het op die manier waarop die proteïen is gevou en dus die vorming van nanoprtikels beïnvloed het. Uitdrukking studies is ook gedoen op die proteïen wat of ‘n Histidienaanhangsel of ‘n leierpeptied of beide bevat het. Dit is egter gevind dat nie die Histidienaanhangsel of die leierpeptied enige invloed gehad het op die nanopartikels wat verkry is nie.Goud reduksie en nanopartikel vorming is verkry deur die reduksie van ‘n disulfied binding, geleë op die oppervlak van die ABC-vervoerder-peptied-bindings-proteïen, met behulp van natrium ditioniet as elektron skenker en reduseermiddel. In die algemeen is daar gevind dat nanopartikels se vorming afhanklik is van die omgewingsparameters, maar beheer van hierdie proses is nie volledig nie. Chemiese reduksie het in sommge gevalle ‘n invloed gehad op die vorming van nanopartikels, maar in geheel kan dit gesien word dat die teenwoordigheid van die proteïen ‘n baie belangrike rol speel in die vertraging van die reaksietempo. Dit kan sorg vir ‘n mate van beheer oor die vorming van nanopartikels en lei tot ‘n meer omgewingsvriendelike, biologiese proses vir die produksie van goud nanopartkels.enMesophilic and thermophilic expression hostPeptide-binding proteinABC transporterThermus scotoductus SA- 01Gold reductionBiosynthesisMetal nanoparticlesNanostructured materialsBiosynthesisTransmission electron microscopyProteins -- SynthesisNanotechnologyDissertation (M.Sc. (Microbial, Biochemical and Food Biotechnology))--University of the Free State, 2010DissertationUniversity of the Free State