Biological synthesis of gold nanoparticles by yeasts
| dc.contributor.advisor | Van Heerden, Esta | |
| dc.contributor.advisor | Piater, Lizelle | |
| dc.contributor.author | Fuku, Sandile Lawrence | |
| dc.date.accessioned | 2018-04-19T10:37:25Z | |
| dc.date.available | 2018-04-19T10:37:25Z | |
| dc.date.issued | 2008-09 | |
| dc.description.abstract | English: Biological systems are used to build nanoparticles of specific morphology and function (Eustis and EI-Sayed, 2005). The difficulty in synthesizing nanoparticles of the desired size, shape and monodispersity directs research into new and redefined synthetic methods. The microbial interaction with metals might also supply eco-friendly methods for metal nanoparticle production. Various yeast species obtained from UNESCO MIRCEN Yeast culture collection at UFS were evaluated for their ability to reduce Au3 + ions into elemental gold nanoparticles by visual analysis. Colour intensity and time taken for the biomass to turn purple were used to select for those organisms which are able to reduce gold. The ability of whole cells to reduce Au3+ ions was dependent on concentration of gold(III) ions and (contact) time. Transmission electron microscopy (TEM) micrographs of Candida viswanathii, Geotrichum fermentans and Rodotorula graminis showed cell bound nanoparticles. Cell free extracts of the above mentioned three species showed enhanced gold reduction over a shorter period. Physicochemical parameters such as pH, gold concentration and temperature influenced the reduction and particle formation. From sub-cellular fractionation, the cytoplasm showed higher gold reduction activity. Partial purification was achieved in two anion exchange chromatography steps and 15 fold nanoparticle gold reduction activity as well as 20 fold nitrate reductase activity. The partially purified fraction exhibited both nanoparticle formation and nitrate reductase activity. The nanoparticles formed were confirmed to be gold by EDS analysis and electron diffraction patterns were characteristic of polycrystalline material. The average size of the formed gold nanoparticles was 15 nm. | en_ZA |
| dc.description.abstract | Afrikaans: Biologiese sisteme word gebruik om nanopartikels te bou met spesifieke morfologie en funksie. Die moeilikheidsgraad in die sintese van nanopartikels met die verlangde grootte, vorm en monodispersiteit rig navorsing na nuwe en hergedefinieerde sintetiese metodes. Die mikrobiese interaksie met metale mag ook eko-vriendelike metodes verskaf vir metaal nanopartikel produksie. Verskeie gisspesies verkry vanaf UNESCO MIRCEN Giskultuurversameling by UVS is geëvalueer vir hul vermoë om Au3 + ione te reduseer na elementêre goud nanopartikels deur visuele analise. Kleurintensiteit en tydsverloop totdat die biomassa na pers verkleur het, is gebruik om te selekteer vir organismes wat goud kon reduseer. Die vermoë van heel selle om Au3 + ione te reduseer was afhanklik van die konsentrasie van die Au3 + ione en kontak tyd. Transmissie eletron mikroskopie (TEM) mikrograwe van Candida viswanathii, Geotrichum fermentans en Rodutorula graminis het assosiasie van nanopartikels met die sitoplasma getoon en sommige was seloppervlakgebonde. Dit mag 'n aanduiding wees dat elke organisme 'n unieke, eiesoortige meganisme het om oormatige goud in sy eie omgewing te verwerk. Sel-vrye ekstrakte van bogenoemde drie spesies het verhoogde goudreduksie getoon in 'n korter tydsperiode met hoër konsentrasies goud. Fisiochemiese parameters soos pH, goudkonsentrasie en temperatuur het reduksie en partikelvorming beïnvloed. Vanaf sub-sellulêre fraksionering het die sitoplasma hoër goudreduksie aktiwiteit getoon. G. fermentans is gekies vir finale karakterisering van die nanopartikel meganismes gebruik deum hierdie gisspesie.Gedeeltelike suiwering van die proteïen/ensiem betrokke in nanopartikel-vorming is gedoen in twee anioon-uitruilingskromatografie stappe. 'n 15-voud nanopartikel goudreduksie aktiwiteit asook 'n 20-voud nitraat reduktase aktiwiteit is getoon met die finale proteïenfraksie. Die gevormde nanopartikels is bevestig as suiwer goud deur (Energie dispersiewe X-straal spektroskopie) EDS analise en die elektron diffraksiepatrone was lI kenmerkend van polikristallyne materiaal. Die gemiddelde grootte van die ,; gevormde goud nanopartikels was 15nm. | af |
| dc.identifier.uri | http://hdl.handle.net/11660/8215 | |
| dc.language.iso | en | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Ions | en_ZA |
| dc.subject | G. fermentans | en_ZA |
| dc.subject | Gold | en_ZA |
| dc.subject | Nanoparticles | en_ZA |
| dc.subject | Reductase | en_ZA |
| dc.subject | Nanoparticles -- Synthesis | en_ZA |
| dc.subject | Nanotechnology | en_ZA |
| dc.subject | Fungi -- Biotechnology | en_ZA |
| dc.subject | Dissertation (M.Sc. (Microbial, Biochemical and Food Biotechnology))--University of the Free State, 2008 | en_ZA |
| dc.title | Biological synthesis of gold nanoparticles by yeasts | en_ZA |
| dc.type | Dissertation | en_ZA |