Immobilization of human thrombomodulin onto PTFE

Human thrombomodulin (hTM) is an endothelial cell-surface glycoprotein and has effective anticoagulant properties. This protein was immobilized onto polytetrafluorethylene (PTFE) surfaces to create biomaterials with enhanced haemocompatibility. The PTFE surface was functionalized by CO2 plasma activation and subsequent vapour-phase graft polymerization of acrylic acid. Surface characterization after plasma treatment, grafting and hTM immobilization was achieved by attenuated total reflection-Fourier transform–infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential and wetting measurements. The activity of immobilized hTM was estimated using the protein C activation test.     

Study on the structures of N-containing melilite Y2Si3O3N4 and Nd2Si2.5Al0.5O3.5N3.5

Rietveld refinements have been used to determine the structure of Y2Si3O3N4 from X-ray data and Nd2Si2.5Al0.5O3.5N3.5 from neutron powder diffraction data. The refinements show that in the melilite phase Y2Si3O3N4 and melilite solid solution Nd2Si2.5Al0.5O3.5N3.5 the distributions of cations and anions are almost identical. They are analogous to the akermanite (Ca2MgSi2O7) structure, with Si/Si,Al atoms at the origin and centre of the unit cell and with four N/N,O atoms forming the SiN4/(Si,Al)(N3.5O0.5) tetrahedra which share corners with SiO2N2/(Si,Al)O2.25N1.75 tetrahedra to form a continuous sheet structure. Each Y3+ or Nd3+ ion is surrounded by eight N/O atoms forming the coordination polyhedron in Y2Si3O3N4 and Nd2Si2.5Al0.5O3.5N3.5 respectively. The arrangement of Al, Si atoms in the tetrahedra in Nd2Si2.5Al0.5O3.5N3.5 structure is also discussed. This revised version was published online in November 2006 with corrections to the Cover Date.