| This work was based on the hypothesis that high performance membranes can be developed through macromolecular functionalization of low-resistance microporous media. New generation materials must be more reliable, highly selective and consume less energy. This study focused on biomolecule functionalization to impart tunability, ion-selectivity and protein recognition to open membrane geometries allowing for enhanced productivity compared to conventional processes.; In recent years, our research group has studied polypeptide functionalized membranes for the development of high capacity sorbents. In addition to toxic metal capture, functionalization with charged poly(amino acids) can also provide opportunities where electrostatic and conformational properties can be utilized for charged-based ion exclusion and controlled transport applications. The presence of these charged multi-functional groups within the membrane pore promotes electrostatic interactions with ions far removed from the pore surface. Thus, ion exclusion is enabled using low-resistance materials. Furthermore, immobilization of poly(L-glutamic acid) allows for conformation-based alteration of membrane properties upon changes in the solution environment. These morphological transitions were investigated using a two-region pore model describing solvent transport. Ion transport was modeled using a 2-D approach based on the extended-Nernst Planck equations coupled with the Poisson equation. This analysis allows for evaluation of the fixed membrane charge and estimation of the electrostatic properties of the immobilized species.; Highly permeable ion-selective membranes were also prepared via immobilization of polyelectrolyte multilayers within the pore structure of microporous supports. Electrostatic pore assembly was achieved through alternate adsorption of cationic and anionic polyelectrolytes. Non-stoichiometric immobilization of charged multilayers within a confined pore leads to an enhanced density of ionizable groups in the membrane phase. This increase in the effective charge allows for Donnan exclusion of ionic species using highly permeable materials.; Biomolecule functionalization was also used for the separation of Tat protein from a complex solution using a recognition-based membrane system. Tat accessibility in the feed solution was influenced by the presence of RNAse, protein concentration and ionic strength. Tat protein produced via membrane separation yielded primarily monomeric forms of the oligopeptide, where as, column chromatography produced polymeric forms. These differences resulted in changes in the neurotoxicity and cellular uptake of the two preparations. |
