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Immobilized heparin: spacer arm effects on biological interactions
Thrombosis Research
|April 1, 1982
Summary
Longer spacer arms on immobilized heparin surfaces enhance anticoagulant activity but do not affect platelet interactions. This suggests immobilized heparin may not directly interact with platelets due to protein layer interference.
Area of Science:
- Biomaterials Science
- Surface Chemistry
- Biomedical Engineering
Background:
- Heparin immobilization on polymer surfaces is crucial for developing biocompatible medical devices.
- Understanding the relationship between spacer arm length and heparin's bioactivity is essential for optimizing surface properties.
Purpose of the Study:
- To evaluate the anticoagulant activity and platelet interactions of heparin immobilized with varying diaminoalkane spacer arm lengths.
- To investigate the influence of spacer arm length on plasma protein adsorption to heparinized surfaces.
Main Methods:
- Anticoagulant activity was assessed using activated partial thromboplastin time (APTT) assays.
- Platelet interactions were evaluated by measuring platelet retention and platelet factor 4 (PF 4) release.
- X-ray photoelectron spectroscopy (XPS) was used to analyze plasma protein adsorption on heparinized surfaces.
Main Results:
- Anticoagulant activity of immobilized heparin increased with longer diaminoalkane spacer arms.
- Spacer arm length did not influence platelet retention or PF 4 release.
- XPS analysis revealed that adsorbed plasma proteins formed a layer preventing direct interaction with the immobilized heparin, regardless of spacer arm length.
Conclusions:
- Increasing spacer arm length enhances the anticoagulant efficacy of immobilized heparin.
- The inability of immobilized heparin to directly interact with platelets, likely due to protein fouling, suggests limitations in its direct antithrombotic mechanism on these surfaces.