Surface coating of hydrophilic-hydrophobic block co-polymers on a poly(acrylonitrile) haemodialyser reduces platelet adhesion and its transmembrane stimulation.

Surface design aimed at reduced adhesion and preserved functions of platelets is of great importance for extracorporeal devices. In this study, a coating technique using hydrophilic-hydrophobic block co-polymers on a hydrophobic poly(acrylonitrile) (PAN) haemodialyser was explored. The hydrophilic block of co-polymers was composed of either poly(methoxy polyethylene glycol methacrylate) or poly(dimethyl acrylamide), and the hydrophobic block was poly(methyl methacrylate). The co-polymers were coated on the dialyser membrane by means of a solution coating method. Upon coating, the hydrophobic block of the co-polymers was anchored on a PAN membrane and the hydrophilic block oriented towards the blood-material interface. This was deduced from water wettability measurements. Significantly reduced transmembrane stimulation of platelets was observed, which was evaluated by determining the intracellular calcium ion concentration of platelets eluted through treated hollow fibres. This suppression was enhanced as the relative fraction of the hydrophilic block of the co-polymers increased. Furthermore, the number of platelets adhering to the co-polymer-coated PAN membrane was drastically reduced. Thus, coating of the hydrophilic-hydrophobic block co-polymers provided better biocompatibility on a hydrophobic PAN dialyser.