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Synthesis and anticoagulant activity of heparin immobilized “end‐on” to polystyrene microspheres coated with end‐group activated polyethylene oxide
Author(s) -
Fry Allyson K.,
Schilke Karl F.,
McGuire Joseph,
Bird Karyn E.
Publication year - 2010
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.31640
Subject(s) - heparin , ethylene oxide , partial thromboplastin time , chemistry , polystyrene , copolymer , polymer chemistry , polymer , coagulation , organic chemistry , biochemistry , medicine , psychiatry
Abstract 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‐μm 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. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.