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Effect of bore fluid composition on microstructure and performance of a microporous hollow fibre membrane as a cation-exchange substrate

Accepted version
Peer-reviewed

Repository DOI


Type

Article

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Authors

Lazar, Radu Alexandru 
Mandal, Isphita 
Slater, Nigel KH 

Abstract

Micro-capillary film (MCF) membranes are effective platforms for bioseparations and viable alternatives to established packed bed and membrane substrates at the analytical and preparative chromatography scales. Single hollow fibre (HF) MCF membranes with varied microstructures were produced in order to evaluate the effect of the bore fluid composition used during hollow fibre extrusion on their structure and performance as cation-exchange adsorbers. Hollow fibres were fabricated from ethylene-vinyl alcohol (EVOH) copolymer through solution extrusion followed by nonsolvent induced phase separation (NIPS) using bore fluids of differing composition (100wt.% N-methyl-2-pyrrolidone (NMP), 100wt.% glycerol, 100wt.% water). All HFs displayed highly microporous and mesoporous microstructures, with distinct regions of pore size <1μm, 5-15μm and up to 50μm in diameter, depending upon proximity to the bore fluid. Scanning electron microscopy (SEM) revealed skins of pore size <1μm at the inner surface of HFs produced with water and glycerol, while NMP bore fluid resulted in a skinless inner HF surface. The HFs were modified for chromatography by functionalising the polymer surface hydroxyl groups with sulphonic acid (SP) groups to produce cation-exchange adsorbers. The maximum binding capacities of the HFs were determined by frontal analysis using lysozyme solutions (0.05-100mgml(-1)) for a flow rate of 1.0mlmin(-1). The NMP-HF-SP module displayed the largest maximum lysozyme binding capacity of all the fibres produced (40.3mg lysozyme/ml adsorbent volume), a nearly 2-fold increase over the glycerol and 10-fold increase over the water variants at the same sample flow rate. The importance of NMP as a bore fluid to hollow fibre membrane performance as a result of inner surface porosity was established with a view to applying this parameter for the optimisation of multi-capillary MCF performance in future studies.

Description

This is the author accepted manuscript. The final version is available via Elsevier at http://www.sciencedirect.com/science/article/pii/S002196731500432X.

Keywords

Cation-exchange, Ion-exchange, Chromatography, Hollow fibre, Microporous, Separation

Journal Title

Journal of Chromatography A

Conference Name

Journal ISSN

Volume Title

1394

Publisher

Elsevier
Sponsorship
The authors would like to acknowledge the financial support of the University of Cambridge CHESS scheme. The authors would like to thank Dr. Jeremy Skepper for help with SEM imaging and assistance by Dr. Bart Hallmark and Matthew Townsend.