Novel thymine-functionalized polystyrenes for applications in biotechnology

This thesis discusses the synthesis and characterization of novel polystyrene microspheres carrying thymine moieties. The novel microspheres were synthesized in free radical emulsion polymerization by two methods. The first method included copolymerizing styrene (St) and 1-(vinylbenzyl)thymine (1-VBT), while the second method was through the substitution of chlorine reactive groups of synthesized poly(styrene-co-p-chloromethylstyrene) copolymers with thymine. Compositional analysis of the functionalized microspheres proved achieving maximum bulk VBT functionality content of 4 mol % and surface content of 20 mol % by the first method, while second method achieved 18 mol % bulk functionality content and 32 mol % surface content. Different investigations were conducted to examine possible applications that thymine moieties imparted to the microspheres. Adsorption of isomers of different phenolic derivatives from hexane was examined, and results demonstrated their chemisorption onto thymine moieties through hydrogen bonding. More preferential adsorption of para isomers was observed than ortho isomers, which was employed to achieve good separation from solution containing both isomers. Next investigation was adsorption of proteins (i.e., BSA and BHb). Results showed that adsorption occurred by both physisorption onto PS backbone and chemisorption via hydrogen bonding onto thymine moieties. Good bioseparation was achieved from solutions containing binary mixtures of BSA and BHb at pH = 7.0. The potential use of the novel microspheres as carriers for Ciprofloxacin HCl was examined. Drug loading was achieved by adsorption at pH = 4.0, while drug release by desorption was demonstrated at pH = 7.0 and 37°C. Finally, a three-phase fluidized bioreactor was design, built and used to demonstrate bioseparation of BSA and BHb proteins from binary mixtures onto commercial anionic resin bearing quaternary amine functionality in chloride form. It is planned to use this bioreactor for protein bioseparation onto the novel thymine functionalized microspheres.