Hemodialysis (HD) is a relatively safe purification technique for curing renal failure. Excess moisture and metabolic wastes (such as urea and creatinine) were removed by HD, and in the meantime, calcium ion, bicarbonate ion and other substances can be supplied. The core element is ultrafiltration hollow fiber membrane (HFM) [1
]. Currently, polyethersulfone (PES) and polysulfone (PSf) membranes are widely used in hemodialysis for their better biocompatibility and functional middle-molecular substance clearances [2
]. However, the biocompatibility of these membranes is still not ideal and needs improvement [3
]. For example, anticoagulants (such as hirudin or heparin) should be added during hemodialysis, owing to the poor anticoagulation property of commercial membranes [5
]. Studies on developing high performance hemodialysis membranes have attracted worldwide attention. So far, many works have been focused on the modification of current membranes for the purpose of enhancing their hemodialysis properties. The most widely used method for improving biocompatibility is to use additives that have excellent biocompatibility rather than the native polymer. PSf blended with polyvinylpyrrolidone (PVP) showed enhanced biocompatibility compared to native PSf [6
]. Although the modification of the currently used materials is an effective way to improve the biocompatibility of hemodialysis membranes, it is far from being clinically applicable, owing to the complexity of the modification process. Therefore, it is urgently needed to find new materials with promising biocompatibility and hemodialysis properties.
Polyvinylidene fluoride (PVDF), a widely used material in the field of water purification, has recently received great attention as a membrane material with regard to its outstanding properties, such as high mechanical strength, thermal stability, anti-ultraviolet radiation, smooth surface and low protein adsorption [7
]. Laroche et al
] pointed out that PVDF had excellent biocompatibility and minimal cell adsorption and tissue response. PVDF has a promising future application in the hemodialysis field. However, the intrinsic hydrophobicity of PVDF limits the practical application in biomedicine [6
]. Therefore, it is essential to improve the hydrophilicity of the material surface.
Polyethylene glycol (PEG) containing copolymers has been extensively investigated to modify the surface property of various industrial membranes, because PEG is considered to be one of the best synthetic non-fouling materials that has the ability to resist protein adsorption. The anti-fouling performance of PEG can be attributed to its unique properties of having a high level of hydrophilicity, vigorous chain mobility and a high extent of coordination with surrounding water molecules [15
An attempt was made to improve the mechanical and permeable properties of PVDF hollow fiber membranes by blending with PEG polymers in this study. At the same time, the preliminary biocompatibility evaluation of materials was studied. Additionally, the specific biocompatibility evaluation of PVDF hollow fiber membranes will be expanded in the next work. The effects of PEG content on membrane morphology were evaluated by scanning electron microscopy (SEM). Furthermore, the influences of different membrane thickness and PEG content on membrane properties were also investigated. The permeation and hydrophilicity of the membrane surface were evaluated by the UF flux of pure water and the water contact angle. The protein rejection and protein adsorption were investigated using bovine serum albumin (BSA).