Heparin was modified and immobilized to surface-activated silica surfaces using two different reaction schemes. End-aminated heparin was reacted with 2-iminothiolane to produce free thiol groups at the terminal ends of the heparin chains. The end-thiolated heparin was immobilized by reaction with a pyridyl disulfide activated poly[ethylene oxide]-poly[propylene oxide]-poly[ethylene oxide] triblock...