Microcapillary membranes for purification of biomolecules
University of Cambridge
Department of Chemical Engineering and Biotechnology
Doctor of Philosophy (PhD)
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Mandal, I. (2016). Microcapillary membranes for purification of biomolecules (Doctoral thesis). https://doi.org/10.17863/CAM.16085
Opportunities exist for alternative chromatography separation media which possess high binding capacity and throughput, avoid column packing, are economically feasible for single-use disposability and work with standard chromatography systems. Two types of microcapillary membranes, hollow fibre membranes (HFM) and microporous walled microcapillary film (MMCF) membranes have been previously studied for a diverse range of filtration applications. The MMCF membranes unique geometry has not yet been studied for separation of biomolecules. The aim of this thesis is to develop microcapillary membranes for proof-of-concept biomolecule separations through various chromatography module constructions, surface chemistries and matrix composition modifications. The microcapillary membranes used in this work have been produced through a non-solvent induced phase separation process using ethylene vinyl alcohol copolymer. The matrices are constructed into two types of modules, straight columns and helical columns, and the flow behaviour and dynamic binding capacity of each is studied. The matrix surface is modified using sulfonic acid groups for cation-exchange chromatography and quaternary amines for anion-exchange chromatography. The straight MMCF module operates on standard AKTATM chromatography systems at pressures of up to 1.5 MPa and linear velocities of up to 54,000 cm h-1. A sharp column breakthrough is observed with a dynamic binding capacity at 10% breakthrough of 13.8 mg lysozyme/ml adsorbent volume. Frontal analysis bio-separation studies of lysozyme and BSA show a purification of 98.8% of lysozyme in the eluted sample. The anion functionalised straight MMCF module has a dynamic binding capacity of 10% breakthrough of 1.26 mg ovalbumin/ ml adsorbent volume, isolating BSA from lysozyme to the limit of detection of the gel assay used. The concept of activated carbon (AC) in membranes for removal of impurities is applied to the HFM matrix geometry by modifying the NIPS process to form AC-HFM mixed-matrix membranes. AC-HFMs with AC compositions of 0.7%, 3.2%, 6.3%, 11.8% and 21.1% by mass are extruded. Generally, as the AC composition of the HFM increases, the average pore size across the capillary membrane decreases, and the overall amount of adsorption of test molecules methylene blue and humic acid increases. This thesis contributes to the study of microcapillary membranes as a chromatography medium which is high capacity, high throughput, and pressure tolerant whilst avoiding column packing. This thesis sets the research area for advanced bioprocessing studies by optimising the porosity and permeability of the microcapillary membranes, studying affinity chromatography, and advanced large biomolecule studies using mixed-matrix microcapillary membrane studies.
This record's DOI: https://doi.org/10.17863/CAM.16085