“CUSHION EFFECT” OF POLYVINYLPIRROLIDONE POLYMER PARTICLES IMPROVES BIOCOMPATIBILITY OF POLYSULFONE DIALYSIS MEMBRANES

Abstract

Some polysulfone (PS) dialysis membranes hydrophilized with poly-vinylpyrrolidone (PVP) have excellent biocompatibility in clinical use. The objective of the present study is to clarify the mechanism how such membranes achieve excellent biocompatibility and furthermore to develop a patient-friendly PS dialysis membrane. Inner surfaces of nine kinds of wet and dry PS hollow-fiber dialysis membranes prepared by varying spinning and sterilization methods were observed by atomic force microscopy (SPM 9500-J3; Shimadzu, Japan). The same observation mode (contact mode) and probe (NP-S; Nihon Veeco KK, Japan) were used to quantitatively evaluate surface structures of wet and dry samples. C5a activity at 60 min was used for evaluating biocompatibility. The more γ-ray irradiated membranes, the more PVP bridged and the more rigid PVP polymer particles (PPP) were formed on the surface, resulting in a lowering of biocompatibility. Softness of PPP works like a cushion and improves biocompatibility, indicating that biocompatibility is determinable by swelling and shrinking behavior of PPP caused by wetting and drying. Gamma-ray sterilization in aqueous glycerin (AG) prevented PPP from becoming rigid and was superior to that in water on biocompatibility. There was no significant difference in biocompatibility between continuous and batch spinning methods.Table