Ligand modification of Pluronic F108 for use in immobilized metal affinity separation of bio-macromolecules

Van Kralingen, Leon (2002-03)

Thesis (MSc)--Stellenbosch University, 2002.

Thesis

ENGLISH ABSTRACT: Inthis work we aim to put into place a system to separate or immobilise biomacromolecules by means ofimmobilised transition metal ions like nickel(II) or copper(II). Although the concept of immobilised metal affmity chromatography (IMAC) has been around since the early 1960's, the metal ions were always immobilised by covalent modification of the support matrix. Recently the concept of IMAC was applied to membranes, and again the metal ion was immobilised by covalent modification of the membrane surface. Inthis study we covalently modified the support matrix by attaching a linear, EDTA type ligand to the hydroxy end groups of a tri-block copolymer (polyethylene oxide (PEO)m = 129 - polypropylene oxide (PPO)n = 56 - polyethylene oxide (PEO)m= 129), Pluronic® F108. The middle block of this polymer, which is hydrophobic, will non-covalently adsorb onto the membrane surface through hydrophobic interaction. The hydrophilic outer blocks, with the ligand modified end groups, will associate with the aqueous substrate exposing the chelated metal ion for interaction with the bio-macromolecules. This affords a system which is recyclable, without replacing the membranes, simply by stripping the expired ligand modified-polymer and adsorbing fresh polymer. A series of model ligands and their complexes were synthesised and characterised, to study the coordination of the ligand around the metal ions. The model compounds were also essential in characterising the final product - the ligand modified Pluronic. Finally the ligand modified Pluronic was tested for its metal binding capabilities. This was done in aqueous solution by qualitatively comparing the UV-VIS spectra of the modified Pluronic with that of the model ligands and complexes. The spectra indicate that metal coordination does take place.

AFRIKAANSE OPSOMMING: In die studie het ons beoog om 'n sisteem daar te stel vir die skei en immobilisering van bio-makromolekules deur middel van oorgangsmetale soos nikkel(II) en koper(II). Alhoewel die beginsel van geïmmobiliseerde Metaal-ioon Affmiteits Chromatografie (IMAC) reeds sedert die vroeë 1960's bekend is, is die metaal ione geïmmobiliseer deur kovalente modifikasie van die draermaterial. Onlangs is die beginsel van IMAC uitgebrei na membrane en ook hierin is die metaalione geïmmobiliseer deur kovalente modifikasie van die membraanoppervlaktes. In die projek het ons die draermateriaal kovalent gemodifiseer deur 'n lineêre EDT A-tipe ligand te koppel aan die hidroksie eindgroepe van 'n tri-blok ko-polimeer (poli-etileen oksied (PEO)m = 129 - poli-propileen oksied (PPO)n = 56 - poli-etileen oksied (PEO)m = 129), Pluronic® FI08. Die middelste blok van die polimeer, wat hidrofobies is, sal nie-kovalent aan die membraan oppervlakte adsorbeer d.m. v hidrofobiese interaksie. Die hidrofiliese buite blokke, met die ligand-gemodifiseerde eindgroepe, sal assosieer met die waterige substraat en die metal ioon blootstel vir interaksie met die biomakromolekules. Dit stel dus 'n sisteem in plek wat herbenut kan word, sonder om die membrane te vervang, deur eenvoudig die ligand-gemodifiseerde polimeer wat verval het te stroop en te vervang met nuwe polimeer. 'n Reeks modelligande en hul komplekse was gesintetiseer en gekarakteriseer om die koördinasie van die ligande rondom die metaal ione te bestudeer. Dié model verbindings was van groot belang in die karakterisering van die finale produk - die ligand-gemodifiseerde Pluronic. Laastens is die ligand-gemodifiseerde Pluronic getoets vir sy metaal bindings vermoeë. Dit is gedoen deur die UV-VIS spectra van die gemodifiseerde Pluronic kwalitatiefte vergelyk met die spectra van die modelligande en komplekse, in waterige oplossings. Die spectra dui aan dat metaalbinding wel plaasvind.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/52918
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