Formation of Highly Aligned Grooves on the Inner Surface of Semi-Permeable Hollow Fiber Membrane for the Directional Axonal Outgrowth

Author(s):  
Yu Long ◽  
Changhong Zhang ◽  
Ning Zhang ◽  
Yong Huang ◽  
Xuejun Wen

It is generally believed that organized neural architecture is essential for both nervous system development, function, and regeneration. In the absence of guidance cues, regenerating axons may lose their directions and become misaligned, resulting in the formation of neuromas and/or misappropriate connections. To help regenerate axons across damaged regions and guide them to appropriate targets, some bridging devices such as microgrooves are being intensively researched to achieve a better directional axonal growth. This paper reports a novel fabrication process to generate a highly aligned groove texture on the inner surface of semi-permeable hollow fiber membranes (HFMs). HFMs were shown to be one of the most promising results in guiding axonal regeneration [1]. The fabrication process utilized a wet phase inversion procedure with polyurethane as model polymer, dimethyl sulfoxide (DMSO) as solvent, and water as nonsolvent. Data indicated that highly aligned groove texture could be formed on the HFM inner surface by carefully controlling phase inversion conditions such as the polymer solution flow rate, and/or nonsolvent flow rate, and/or polymer solution concentration ratio. The texture forming mechanism is qualitatively explained using a polyurethane (PU)-DMSO-water ternary phase diagram and the process dynamics. Axonal outgrowth on the HFM with aligned grooves showed the highly aligned orientation and improved axonal outgrowth length. This study will eventually lead to a new and effective way to engineer nerve grafts based on a highly aligned three dimensional scaffold for the spinal cord injury and nerve damage treatment.

Author(s):  
Yu Long ◽  
Ning Zhang ◽  
Yong Huang ◽  
Xuejun Wen

It is generally believed that organized neural architecture is essential for nervous system development, function, and regeneration. In the absence of guidance cues, regenerating axons may lose their directions and become misaligned, resulting in the formation of neuromas and/or misappropriate connections. To help regenerate axons across damaged regions and guide them to appropriate targets, some bridging devices such as microgrooves are being intensively researched to achieve a better directional axonal growth. This paper reports a novel fabrication process to generate a highly aligned groove texture on the inner surface of semipermeable hollow fiber membranes (HFMs). HFMs have demonstrated promising results in guiding axonal regeneration. The fabrication process utilized a wet phase-inversion procedure with polyurethane (PU) as model polymer, dimethyl sulfoxide (DMSO) as solvent, and water as nonsolvent. Data indicated that highly aligned groove texture could be formed on the HFM inner surface by carefully controlling phase-inversion conditions such as the polymer solution flow rate, and/or nonsolvent flow rate, and/or polymer solution concentration ratio. The texture forming mechanism is qualitatively explained using a PU-DMSO-water ternary phase diagram and the dynamics of fluid instability. Axonal outgrowth on the HFM with aligned grooves showed the highly aligned orientation and improved axonal outgrowth length. This study may eventually lead to a new and effective way to fabricate nerve grafts for the spinal cord injury and nerve damage treatment based on this highly aligned three dimensional scaffold.


2017 ◽  
Vol 12 (1) ◽  
Author(s):  
A. Mansourizadeh ◽  
A. F. Ismail

In this study, porous hydrophobic polyvinylidene fluoride (PVDF) hollow fiber membranes were fabricated via a wet phase inversion process. In order to improve the phase inversion rate and provide porous membranes, 4 wt.% lithium chloride (LiCl) was used in the spinning dope. The prepared membrane morphology was studied using field emission scanning electron microscopy (FESEM). Chemical CO2absorption by NaOH solution (1M) was conducted through the PVDF hollow fiber membrane contactor. The effect of the main operating condition such as absorbent temperature, CO2 pressure and absorbent flow rate on the performance of CO2 absorption was investigated. From FESEM examination, the membrane possesses an almost sponge–like structure with ultra thin skin layer. Results of CO2absorption test showed that by increasing the absorbent flow rate the CO2 flux increased which confirmed the existence of liquid side mass transfer resistance. It was found that by increasing the absorbent temperature the CO2 flux considerably improved. Meanwhile, the effect of CO2 pressure on the absorption rate was insignificant. Therefore, it can be concluded that by applying a porous hydrophobic membrane with improved structure and optimizing the operating conditions, high CO2 removal efficiency can be achieved through gas–liquid membrane contactors


2016 ◽  
Vol 1133 ◽  
pp. 141-145 ◽  
Author(s):  
Norfazliana Abdullah ◽  
Mukhlis A. Rahman ◽  
A.F. Ismail ◽  
M.H.D. Othman ◽  
Juhana Jaafar

Alumina hollow fiber membrane with asymmetric structure has been developed using phase inversion technique followed by sintering process. The formation of asymmetric alumina hollow fiber was influenced by a phenomenon known as hydrodynamically unstable viscous fingering. A desired morphology of the ceramic hollow fiber membrane, that consists of 52 % of finger-like and the rest is sponge-like structure, is tailored by controlled parameters during membrane fabrication process. The result shows that the ratio of alumina/PESf should be reduced to 6. At this ratio, the finger-like structure can be easily formed with inner and outer diameters were 1.11 mm and 2.05 mm respectively. From the given thickness, approximately 243 µm of finger-like length can be developed originating from the lumen of hollow fiber.


2020 ◽  
Author(s):  
Zhong Sheng Tai ◽  
Mohd Hafiz Dzarfan Othman ◽  
Mohd Irfan Hatim Mohamed Dzahir ◽  
Siti Khadijah Hubadillah ◽  
Khong Nee Koo ◽  
...  

Abstract Low-cost green ceramic hollow fiber membranes (CHFM) were successfully designed and fabricated from the industrial waste ash, palm oil fuel ash (POFA) via phase inversion-based extrusion/sintering techniques for water filter application. The extrusion process parameters such as suspension viscosity, air gap distance, and bore fluid flow rate were systematically explored to produce the membrane with the desired morphology. A high suspension viscosity would result in a small macro-voids structure. Moreover, a high air gap distance would induce fiber with long macro-voids structure, while a low bore fluid flow rate would lead to the formation of distorted lumen structure. The effect of sintering temperature towards CHFM was also studied in detail. An increase in sintering temperature improved the membrane bending strength, but also adversely affected the pure water flux due to lower porosity and higher tortuosity. The developed membranes achieved excellent bending strengths of > 75 MPa at relatively low sintering temperatures than the alternative ceramic counterparts, due to its high potassium oxide, K2O content, which acted as the low melting point sintering aid. The relatively low sintering temperature of POFA-derived CHFMs could reduce the energy consumption and sintering duration, which could be more economically attractive, as compared to their ceramic counterparts, thus benefiting industrial users.


Author(s):  
Zhong Sheng Tai ◽  
Mohd Hafiz Dzarfan Othman ◽  
Azeman Mustafa ◽  
Mohd Irfan Hatim Mohamed Dzahir ◽  
Siti Khadijah Hubadillah ◽  
...  

2019 ◽  
Vol 14 ◽  
pp. 155892501989564
Author(s):  
Ling Lin ◽  
Shao-Wen Yao

This article studies the ion release from an unsmooth inner surface of a hollow fiber. A fractal diffusion model is established using the fractal derivative, and the effect of the fractal dimension on the ion release is elucidated. The present theory provides a theoretical basis for the optimization of a hollow fiber contained silver ions for practical applications.


2013 ◽  
Vol 49 (87) ◽  
pp. 10326 ◽  
Author(s):  
Kang Huang ◽  
Ziye Dong ◽  
Qianqian Li ◽  
Wanqin Jin
Keyword(s):  

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Elham M. El-Zanati ◽  
Eman Farg ◽  
Esraa Taha ◽  
Ayman El-Guindi ◽  
Heba Abdallah

Abstract Multi-bore hollow fiber membranes were prepared through phase inversion spinning process using new locally designed spinnerets of various geometrical shapes. The spun cylindrical-like, rectangular or ribbon-like, and triangular-like are prepared, dried, and characterized by scanning electronic microscope. Fibers of circular (seven, five, and four bores) shape, rectangular of five bores, and triangular of three bores were chosen to study the effect of both geometrical configuration and the number of bores on the amorphous structure and the mechanical properties of the membranes. Membrane geometry, surface amorphous, and bore arrangements are very sensitive to the operating conditions, especially the extrusion and drawing rates. Three polymeric blends of different compositions are used to prepare multi-bore hollow fiber membranes. This study revealed that the blend composition of PES 16%, PVP 2%, PEG 2%, diethylene glycol 2%, and NMP 78% gives excellent mechanical properties. Optimization of the preparation conditions also developed, where the dope flow rate, the bore flow rate, and the air gap were 1.14 cm3 s−1, 1.1 cm3 s−1, and 0 cm, respectively. Furthermore, this study proved that the circular arrangement has high mechanical strength. The prepared seven-MBHF membranes were applied in the membrane distillation process, a solution of 35 g/l NaCl was used to test the membrane performance, and the achieved flux and rejection were 28.32 L/m2 h and 98.9%, respectively. This performance demonstrated that the prepared membrane in this way is suitable to compete with conventional reverse osmosis technology that uses single track hollow fibers.


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