Permselectivity of nonporous polyurethane membranes for immunoisolation. I. The influence of hydrogen bonding

Nonporous polyurethane membranes were synthesized using toluene 2,4-diisocy anate (TDI), polypropylene glycol (PPG), or polytetramethylene glycol (PTMG ) as polyols and 1,4-butanediol as chain extender. The percentage of hard s egments was varied keeping the NCO/OH ratio constant as 1. 1. The permeatio n of glucose, albumin, and insulin through these membranes was studied usin g spectrophotometric assays. The permeation of glucose was found to be depe ndent on the hard segment content and hydrophobicity of the polyols, wherea s insulin permeation was found to vary with the hydrogen bonding and hard s egment content. The permeation of albumin was almost negligible in both sys tems. As the synthesized nonporous polyurethanes allow the transport of the nutrients' glucose and insulin and prevent the transport of albumin with a molecular weight of 60,000 and immunoglobulins with a molecular weight of 150,000, the membranes are proposed as potential encapsulation matrices for the immunoisolation of islet cells. (C) 1999 John Wiley & Sons, Inc.