PHOTOCHEMICAL IMMOBILIZATION OF HEPARIN, DERMATAN SULFATE, DEXTRAN SULFATE AND ENDOTHELIAL-CELL SURFACE HEPARAN-SULFATE ONTO CELLULOSE MEMBRANES FOR THE PREPARATION OF ATHROMBOGENIC AND ANTITHROMBOGENIC POLYMERS

Heparin (HE), dextran sulphate (DX) of molecular weight 40000 and 500000, dermatan sulphate (DS) and endothelial cell surface heparan sulphate (ES-HS) were immobilized covalently onto cellulose membranes (Visking(R) dialysis tubes) using the photochemical heterobifunctional reagent 4-azido-1-fluoro-2-nitrobenzene (AFNB); 120 pmol HE/cm(2) and 40 pmol DS/cm(2), 3.4 pmol DX 500 000/cm(2), 50 pmol DX 40 000/cm(2) and 3.6 pmol ES-HS/cm(2) were immobilized. The platelet adhesion of the modified membranes was measured in a modified Baumgartner perfusion chamber with citrated human blood at a defined shear rate. Membranes modified with DX 40 000 and DX 500 000 showed 80% and 30% platelet adhesion, respectively, heparinized and DS coated membranes showed 50% and 60% platelet adhesion, respectively, compared with a subendothelial matrix (100% platelet adhesion). ES-HS modified membranes showed no platelet adhesion.