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A major challenge in the development of wearable artificial kidneys lies in the efficient removal of urea, which is found at an extremely high concentration in the blood of patients with chronic kidney disease (CKD). Urease is an enzyme that hydrolyzes urea. While it can efficiently remove urea, toxic ammonium is produced as a byproduct. In this study, nanofibers capable of removing both urea and ammonium from blood were fabricated. Specifically, urease was immobilized on electrospun poly(ethylene-co-vinyl alcohol) (EVOH)/chitosan nanofiber membranes via covalent crosslinking. Chitosan not only helped covalent immobilization via its free amino groups, but also improved hemocompatibility by suppressing protein adhesion. The resulting urease-immobilized EVOH/chitosan nanofibers exhibited an outstanding urea removal performance of 690 mg/g per hour. For ammonium removal, EVOH nanofiber membranes containing sodium cobalt(II) hexacyanoferrate(II) (NaCoHCF), an ammonium adsorbent, were prepared. The fabricated EVOH/NaCoHCF membranes exhibited an ammonium adsorption capacity of 135.5 mg/g. The two types of nanofiber membranes were combined to form a double-layered nanofiber membrane that was placed in a filter holder for continuous-flow cycling experiments. Under such conditions, all urea at a concentration similar to that in the blood of CKD patients was degraded within 1 hour, and ammonium production was reduced by approximately 90% of the normal level. This double-layered nanofiber membrane is a novel material that can achieve both urea degradation and ammonium adsorption, and is expected to advance the development of wearable artificial kidneys, a game-changer in the treatment of CKD.

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  This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Materials & Interfaces, copyright © 2024 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsami.4c16068

Keyword: nanofibers, wearable artificial kidney, urease, electrospinning, chitosan

Date published: 2024-12-11

Publisher: American Chemical Society (ACS)

Journal:

• ACS Applied Materials & Interfaces (ISSN: 19448252) vol. 16 issue. 49 p. 67399-67410

Funding:

• Japan Society for the Promotion of Science JP20H05877
• Japan Society for the Promotion of Science JP23KJ0260
• Ministry of Education, Culture, Sports, Science and Technology

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5304

First published URL: https://doi.org/10.1021/acsami.4c16068

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Updated at: 2025-11-25 08:30:15 +0900

Published on MDR: 2025-11-25 08:21:37 +0900