Design of robust hollow fiber membranes using an advanced co-extrusion technology for enhanced hemodialysis

Abstract

Tailoring an efficient hollow fiber (HF) membrane for enhanced hemodialysis requires precise control over membrane morphology, wall thickness, porosity, and pore size on both the lumen and shell sides. Herein, we fabricated the hollow fibers with a simple but effective method of involving a two-phase flow composed of a dope solution and a solvent, co-discharged from the inner and outer channels of a triple orifice spinneret, respectively. Altering the composition of the center bore and the outer channel allowed us to optimize the morphology and pore size of both the lumen and shell sides of the HF synergistically, aiming to improve the removal of uremic toxins. Gradually increasing the fraction of N-methyl-2-pyrrolidone (NMP) in the center bore fluid promoted porosity and enlarged pore size on the lumen side. Concurrently, controlling the composition of the outer channel played a crucial role in tailoring the shell side, leading to the formation of opened pores to a microscale (1.9–3.3 µm). Consequently, the hemodialysis test revealed that M#1-M#4 using an advanced co-extrusion method exhibited superior uremic toxins removal compared to M#0 using a conventional method (i.e., single nozzle). Thanks to its outstanding properties (e.g., very thin wall, high porosity, and narrowed pore size distribution), M#4 exhibited the lowest protein leakage (0.117 % e.g., sieving coefficient of 0.00117), and the highest removal of urea (124,865 mg/m2) and creatinine (6,468 mg/m2). The proposed HF membrane outperformed a commercial membrane in terms of uremic toxins removal and minimized protein leakage, highlighting its considerable potential for hemodialysis application. © 2024 Elsevier B.V.