3D printed monolith adsorption as an alternative to expanded bed adsorption for protein purification.

Type of content
Theses / Dissertations
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Thesis discipline
Product Design
Degree name
Doctor of Philosophy
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Journal Title
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Language
English
Date
2023
Authors
Pei, Yuanjun
Abstract

The fluid flow and chromatographic performances of various cellulose three-dimensional-printed Monolith Adsorption (PMA) columns designed from a triply periodic minimal surface geometry, the Schoen Gyroid or Schwarz Diamond 2, were compared in this thesis. The structures examined had designed hydraulic diameters between 203 and 458 μm and voidages of 40% ~ 60% and were functionalized with a quaternary amine anion exchange ligand. The tests included four aspects: column efficiency, porosity, static binding capacity and dynamic binding capacity for various load volumes and flow rates. The results show that all Gyroid structures allowed efficient passage of yeast cells (> 97%) over a wide range of interstitial velocities (191 to 1911 cm/h) while maintaining a low pressure drop (< 0.1 MPa). The structure with a voidage of 40% and a hydraulic diameter of 203 μm showed the best performance in all aspects evaluated. Bovine serum albumin (BSA) recoveries for all Gyroid structures (27% ~ 91% when the loaded volume was 180 mL) were significantly affected by hydraulic diameter, mean channel wall thickness, velocity and voidage.

Two anion exchange PMA columns of different structures and lengths were directly compared with commercial Expanded Bed Adsorption (EBA) (Cytiva Streamline Q XL) columns. Compared with a 60% PMA column and the EBA column at 4 and 6 mL/min, whose stationary phase volumes were the same, the 40% PMA column had the highest BSA binding capacity/per CV mL after loading a 4 L sample, regardless of the addition of yeast cells (above 85 mg/per CV mL when with yeast cells) with Height Equivalent to a Theortical Plate values of 0.90 ~ 1.13 cm. The PMA did not have the bed instability issue encountered in EBA and shortened overall operating time compared to that of EBA, because of a wider range of possible flow rates.

Protein A could be immobilized on PMA columns made of agarose hydrogels via three different methods and all of these protein A immobilized columns could effectively bind with human immunoglobulin G (IgG). When the ligand density was 2 ~ 4 mg/per gel mL, a high level of IgG static binding capacity of over 20 mg/per gel mL could be achieved by using site-specific immobilization with spacers.

PMA thus potentially provides an appealing alternative to EBA, retaining the latter’s advantages, while eliminating fluidisation issues and minimising both processing time and buffer consumption.

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