Synthesis and anticoagulant activity of heparin immobilized "end-on" to polystyrene microspheres coated with end-group activated polyethylene oxide.
Thiol groups were introduced to unfractionated heparin (UFH) and end-aminated heparin (HepNH(2)) by reaction with 2-iminothiolane under conditions favoring selective modification of terminal over primary amines. End-thiolated heparin retained anticoagulant activity as shown by the activated partial thromboplastin time (aPTT) and anti-Factor Xa (anti-FXa) assays. Thiolated heparins were linked to pyridyl-disulfide activated poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymers adsorbed to 1.15-mum polystyrene microspheres. Surface loadings were similarly low for each type of thiolated heparin. No anticoagulant activity was observed with aPTT assays of heparinized microspheres, due either to the presence of an insufficient amount of immobilized heparin, or to steric constraints inhibiting the formation of a functional heparin-antihrombin complex. However, immobilized heparin retained substantial anti-FXa activity, with significantly greater activity exhibited by the end-thiolated HepNH(2) than the internally (randomly) thiolated UFH.
School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, Oregon 97331, USA.
Allyson K
AK
Fry
Karl F
KF
Schilke
Joseph
J
McGuire
Karyn E
KE
Bird
D000327:Adsorption; D000588:Amines / Q000737:chemistry; D000925:Anticoagulants / Q000737:chemistry / Q000494:pharmacology; D001672:Biocompatible Materials / Q000737:chemistry / Q000494:pharmacology; D001777:Blood Coagulation / Q000187:drug effects*; D065427:Factor Xa Inhibitors; D006493:Heparin / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D008422:Materials Testing; D008863:Microspheres; D015394:Molecular Structure; D010314:Partial Thromboplastin Time; D011092:Polyethylene Glycols / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D011409:Propylene Glycols / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry
D000588:Amines; D000925:Anticoagulants; D001672:Biocompatible Materials; D065427:Factor Xa Inhibitors; C116176:PEO-PPO-PEO; D011137:Polystyrenes; D011409:Propylene Glycols; D013438:Sulfhydryl Compounds; D011092:Polyethylene Glycols; D006493:Heparin