IMMOBILIZATION OF HIGH-AFFINITY HEPARIN OLIGOSACCHARIDES TO RADIOFREQUENCY PLASMA-MODIFIED POLYETHYLENE

Oligosaccharides of heparin with high affinity for antithrombin III (A TIII) have been immobilized onto surface-modified NHLBI Primary Refere nce low density polyethylene (PE). PE was modified by radiofrequency p lasma polymerized (<150 nm thick) films derived from N-vinyl-2-pyrroli done (PPNVP) or allyl alcohol (PPAA), and coupled by chemical derivati zation to either 3-aminopropyltriethoxysilane or amino-terminated poly (ethylene oxide). High affinity heparin oligosaccharides (HA-heparin, anti-factor Xa activity of 592 +/-120 IU/mg) prepared by partial deami native cleavage of commercial crude heparin and fractionated by agaros e-ATIII affinity chromatography, were immobilized to surface-modified PE by reductive amination. The anticoagulant activity, as determined b y a chromogenic assay for the inhibition of factor Xa, was estimated t o be 30-70 mIU/cm2, with binding estimated to be 56-119 ng/cm2. The hi ghest activity was obtained for the HA-heparin immobilized to PE modif ied by PPNVP with a PEO spacer. Visual confirmation of ATIII binding t o immobilized HA-heparin was demonstrated by a gold-labeled double ant ibody method with imaging by SEM.