Surface modification of poly(butylene terephthalate) nonwoven by photochemistry and biofunctionalization with peptides for blood filtration

Effect of membrane parameters and filter structure on the efficiency of leukocyte removal by electrospun poly(ethylene-co-vinyl alcohol) membranes

Electrospinning technology is an experimentally verified tool for the generation of membranes with competing efficiency useful for leukodepletion filter, customarily used in blood banks to lessen the risks with blood transfusions. Even though a few electrospun polymers have been reported to be efficient leukodepletion filter membranes, poly(ethylene-co-vinyl alcohol) (EVAL) being one among, owe to their exceptional advantage of being electrospun from a non-toxic solvent like rubbing alcohol. Besides their excellent blood compatibility, EVAL membranes proffer a leukodepletion performance nearly as same as that of commercial leukodepletion filters. However, the role of various membrane parameters on the leukodepletion efficiency of electrospun EVAL membranes need to be disclosed in advance to their commercialization. Hence this study is an attempt to disclose the ability of electrospinning to being tuned towards the fabrication of filters with different membrane parameters including fiber diameter and pore diameter, with a typical example of EVAL. In addition, the impact of filter design upon the leukodepletion performance was also unveiled by comparing a symmetric filter where all the membranes were of uniform pores with that of an asymmetric filter where the pore sizes of upper and lower layer in the filter was different. The results of blood filtration experiments through the developed prototype filters underline the superiority of asymmetric filters over to symmetric one and, the asymmetric filters wherever the fiber diameter was 1.8 and 3 μm, offered rapid and excellent leukodepletion. Membranes with thinner fibers showed an increased flow resistance. The pore sizes of the membranes being 9 - 29 μm, larger than the size of blood cells, alludes to the direct adhesion of leukocytes to filter membranes as the major mechanism of leukocyte removal. Hence it is concluded that despite the suitability of electrospinning for fabrication of leukodepletion filter media, the use of nano-dimension fibers is not preferred for leukocyte adhesion filter when the material of choice is such a polymer with ideal surface chemistry, wettability and inherent ability for leukocyte binding.

Tuning surface properties of poly(butylene terephthalate) melt blown fibers by alkaline hydrolysis and fluorination

The wetting properties of poly(butylene terephthalate) (PBT) melt blown fibers were tuned by alkaline hydrolysis and subsequent fluorination. Fiber mats were exposed to a NaOH methanol solution for controlled periods of time at several temperatures, resulting in surface hydrolysis (h-PBT). Subsequent simple solution chemistry was applied to the h-PBT fibers, leading to fluorination of the surface (f-PBT) and the transformation of the wetting properties of the material. Electron microscopy revealed that hydrolysis leads to a textured surface that is retained in the fluorinated product. Sessile drop wetting measurements demonstrated superhydrophilicity for the h-PBT fiber mats and sticky superhydrophobicity with the f-PBT fiber mat.