Development of a haemocompatible pO2 sensor with phospholipid-based copolymer membrane

This paper describes research to improve the haemocompatibility of an intravascular pO2 sensor utilizing a novel copolymer membrane. This material is based on a methacrylate monomer having an electrically neutral head group, 2-methacryloyloxyethyl phosphorylcholine (MPC), copolymerized with n-butyl methacrylate (BMA). The MPC mimics the outer layer lipid structure of the red blood cell membrane, and thus poly (MPC-co-BMA) could be expected to show excellent compatibility with blood. In this paper the methods of preparation of a pO2 sensor covered with different types of membrane, including polyetherurethane (PU), polyvinyl chloride (PVC), poly (MPC-co-BMA) and a compound membrane [PVC+poly (MPC-co-BMA)] are described. The surface chemical structure of the different types of membrane were characterized with Fourier transform infrared spectroscopy. Scanning electron microscopy was used to examine the surface contamination after the sensors had been used in blood. The properties of the sensors were first assessed in phosphate-buffered solution, and the short-term and long-term performances were then demonstrated by use of buffer with mixed proteins, serum and whole human blood. The sensors coated with poly (MPC-co-BMA) and PVC+poly (MPC-co-BMA) membranes showed stable behaviour in static human blood, whereas the sensors with PU and PVC membrane were subject to a continuous signal deterioration during the test period.