Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/161530
Title: Aquaporin-based membranes made by interfacial polymerization in hollow fibers: visualization and role of aquaporin in water permeability
Authors: Sharma, Loveena
Ye, Li
Yong, Clare
Seetharaman, Ramya
Kho, Kailing
Surya, Wahyu
Wang, Rong
Torres, Jaume
Keywords: Science::Biological sciences
Engineering::Environmental engineering
Issue Date: 2022
Source: Sharma, L., Ye, L., Yong, C., Seetharaman, R., Kho, K., Surya, W., Wang, R. & Torres, J. (2022). Aquaporin-based membranes made by interfacial polymerization in hollow fibers: visualization and role of aquaporin in water permeability. Journal of Membrane Science, 654, 120551-. https://dx.doi.org/10.1016/j.memsci.2022.120551
Project: RT13/19 
Journal: Journal of Membrane Science 
Abstract: Aquaporins are water channel proteins with high permeability and solute rejection, making them ideal components for the preparation of desalination biomimetic membranes. In one strategy, E. coli aquaporin Z (AqpZ) proteoliposomes are immobilized in a polyamide layer formed by interfacial polymerization at the inner surface of hollow fibers. However, once polymerization occurs, the system is almost a black box where it is difficult to disentangle the relative contribution to performance of (i) water permeation through AqpZ channels and (ii) the possible modification of the properties or structure of the polymer layer by the mere presence of protein and lipid. Indeed, the fate of protein and lipid once the polymer is formed, and how much of it is actually used, is under debate. Also, the performance of these modules has been reported to be stable over several months. This is intriguing because of the expected degradation of functional AqpZ and lipid with time. Herein, we used lipid and AqpZ, both fluorescently labeled, to unequivocally localize both components only at the inner surface of the hollow fibers. To characterize module performance, we tested about 30 half-inch modules containing five hollow fibers each. Those reconstituted with wild type AqpZ produced higher permeability (∼8.5 ± 0.9 LMH/bar) than those reconstituted with AqpZ mutant (R189A) (∼5.6 ± 1.7 LMH/bar) or lipid-only liposomes (3.7 ± 1.1 LMH/bar). However, while these differences are significant, they are smaller than expected from the comparison of relative permeabilities of membranes incorporating wild-type AqpZ, R189A mutant and only-lipid. In addition, we show that in a five-month long experiment, performance of two of these modules showed only minor deterioration, if any, which is not consistent with the observed rapid degradation of proteoliposomes at room temperature. Overall, these data obtained in this set-up suggests that although both AqpZ and lipid are localized at the inner of the hollow fibers, they mainly behave as additives that modify the properties of the robust polyamide layer. A small contribution of AqpZ channel activity to module performance is possible, but to be significant it would require full coverage and a higher protein density in the proteoliposomes, which at present cannot be achieved in the current protocol.
URI: https://hdl.handle.net/10356/161530
ISSN: 0376-7388
DOI: 10.1016/j.memsci.2022.120551
Schools: School of Biological Sciences 
School of Civil and Environmental Engineering 
Research Centres: Nanyang Environment and Water Research Institute 
Singapore Membrane Technology Centre 
Rights: © 2022 Elsevier B.V. All rights reserved.
Fulltext Permission: embargo_20240722
Fulltext Availability: With Fulltext
Appears in Collections:CEE Journal Articles
NEWRI Journal Articles
SBS Journal Articles

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