Abstract
This study introduces the formation of a composite cellulose acetate (CA) membrane for the removal of blood cells from blood-derived solutions. A vapor-induced phase separation (VIPS) CA membrane formed the bottom layer of the composite membrane. The exposure time to vapors was adjusted with the aim to open the pores of the surface exposed to the nonsolvent and obtain a membrane with a mean pore size of less than 0.4 μm. A 20 min exposure led to few pores in the microfiltration range decorating the top surface, while much more numerous pores were observed on the bottom surface in contact with the substrate during the phase-inversion process. Differences between the top and bottom surface porosity in turn influenced wetting by water. The membranes with fastest top and bottom surfaces wettability were selected. Then, nanofibers with a mean pore size of 2.8 ± 0.3 μm were formed by electrospinning a CA solution on the bottom surface of the VIPS membrane. It resulted in the formation of a composite membrane with an asymmetric structure (large top surface pores and smaller bulk and bottom surface pores). The membranes were proven to be nonhemolytic (hemolysis rate <2%) and showed a plasma clotting time in the range 16-22 min. Applied to the gravity-driven filtration of platelet-poor plasma, platelet-rich plasma, and 10-fold and 5-fold dilutions of whole blood, complete blood count analyses showed that the optimized membrane referred to as 15V-15E could separate all platelets, red blood cells, and white blood cells from plasma (100% removal in each case). In addition, the hemolysis of the filtrate obtained with membrane 15V-15E after separation of the 5-fold dilution was extremely low. While the electrospun layer proved efficient for the gradual removal of most cells, SEM and confocal images also highlighted the efficacy of the VIPS layer to reject cells that managed to penetrate deeper in the bulk. However, a VIPS membrane alone failed (no flow) justifying the need for the composite structure. Overall, these membranes show significant potential for facilitating the separation of cells from plasma, which could be applied to the detection of biomarkers in plasma.