Issue 27, 2024

Biocatalytic PEI–PSS membranes through aqueous phase separation: influence of casting solution pH and operational temperature

Abstract

Biocatalytic membranes combine the separation properties of membranes and the catalytic abilities of enzymes, holding great promise for industries where both purification and conversion are required. In this work, polyelectrolyte complex membranes incorporated with lysozyme were prepared using polyethyleneimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS) through a one-step and mild pH shift aqueous phase separation (APS) approach. The effects of lysozyme addition and casting solution pH on the membrane properties were studied. All the membranes, both with and without added lysozyme, exhibited asymmetric structures with relatively dense top surfaces and porous cross-sections with finger-like macrovoids. The incorporation of lysozyme did not significantly influence the structure and permeability of the formed membranes. The PEI–PSS biocatalytic membranes exhibited temperature dependent enzymatic activity. The activity strongly increased with increased operational temperature, with the highest activity of 4.30 ± 0.15 U cm−2 at 45 °C. This indicates a responsive effect, where a higher temperature leads to some swelling of the polyelectrolyte complex membrane, making the enzyme more accessible to the used substrate. Moreover, the biocatalytic membranes demonstrate desirable enzymatic stability, maintaining 60% activity even after 60 days of storage. This study validates the potential of the water-based APS process as a straightforward approach for integrating enzymes into responsive biocatalytic membranes.

Graphical abstract: Biocatalytic PEI–PSS membranes through aqueous phase separation: influence of casting solution pH and operational temperature

Supplementary files

Article information

Article type
Paper
Submitted
14 Mar 2024
Accepted
17 Jun 2024
First published
21 Jun 2024
This article is Open Access
Creative Commons BY license

Soft Matter, 2024,20, 5425-5434

Biocatalytic PEI–PSS membranes through aqueous phase separation: influence of casting solution pH and operational temperature

L. Li, M. I. Baig, W. M. de Vos and S. Lindhoud, Soft Matter, 2024, 20, 5425 DOI: 10.1039/D4SM00311J

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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