PHYSICOCHEMICAL AND BIOLOGICAL STUDIES OF CORONA-TREATED ARTIFICIAL MEMBRANES USED FOR PANCREATIC-ISLETS ENCAPSULATION - MECHANISM OF DIFFUSION AND INTERFACE MODIFICATION

The artificial AN69 membrane (Hospal), a synthetic copolymer composed of acrylonitrile and sodium methallyl sulphonate suitable for pancreat ic islet encapsulation, was submitted to physicochemical treatment (Co rona discharge) to improve its insulin permeability. X-ray photoelectr on spectroscopy (XPS) analysis of the AN69 membrane indicated the pres ence of up to two molecular layers of glycerol at its surface while th e surface energies revealed the presence of hydrophilic sites (-SO3Na/ glycerol) located at the membrane surface and acrylonitrile hydrophobi c groups inside the material. The Corona discharges decreased the numb er of glycerol molecules at the membrane surface and from a biological point of view, produced a threefold increase in insulin diffusion. Fu rthermore, the biocompatibility of the treated membrane was preserved after 1 year of intraperitoneal implantation. The increase in insulin permeability should result from a decrease of the membrane polarity an d of a steric hindrance in pores. Thus, Corona discharge treatment may serve to optimize the properties of artificial membranes used for pan creatic islets encapsulation. (C) 1997 John Wiley & Sons, Inc.