Abstract
Many synthetic polymer dialysis membrane materials like polysulfone (PSf) and polyester-polymer alloy (PEPA) are hydrophobic polymers. Hence in preparing the membranes, a hydrophilic modifier of polyvinylpyrrolidone (PVP) should be added to hydrophilize them in order to suppress plasma protein adsorption on their surfaces. In the present study, we evaluated both PVP distributions and surface characteristics of dialysis membranes and films from a nanoscale perspective. We determined adsorbability between plasma proteins immobilized on the probe and PVP containing PSf films from the force-curve measurement by atomic force microscopy (AFM). The adsorption of albumin was inhibited by the presence of PVP on film surfaces more significantly than that of more hydrophobic fibrinogen. Furthermore, we performed nanoscale functional-group analysis of dialysis membranes made from PSf and PEPA by using near-field infrared microspectroscopy (NFIR). NFIR is a useful analysis technique for obtaining submicroscale to nanoscale chemical information. The nanoscale NFIR analysis showed heterogeneous distribution of PVP on the membrane surfaces and difference in the PVP homogeneities of different dialysis membranes.
