Heparin with Different Molecular Weight on Hemocompatibility and Adsorption of Activated Carbon

Abstract

Activated carbon (AC) is an effective adsorbent for creatinine removal in hemoperfusion. However, the hemocompatibility and adsorption capacity of AC was required to be improved further. Heparin has different anticoagulant mechanisms due to its different molecular weights. Thus, it was necessary to study the surface modification with unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) on improvement of hemocompatibility and adsorption. In this study, UFH and LMWH were, respectively, grafted on AC through polyethyleneimine as an intermediate layer. The modification of AC regarding morphology, mechanical strength, and pore structure was characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), texture analyzer (TA), and surface area analyzer. It was found that, compared with AC, the morphology and mechanical strength of AC-UFH and AC-LMWH could be well maintained, but the specific surface area was decreased due to the grafting of macromolecules. Furthermore, AC-UFH and AC-LMWH showed better hemocompatibility on protein adsorption, clotting time, and platelet activation compared with AC, in which AC-LMWH had lower fibrinogen adsorption and longer clotting time than AC-UFH. In addition, it was found that AC, AC-UFH, and AC-LMWH had no significant effect on blood cell composition. Finally, the adsorption capacity of adsorbents for creatinine was evaluated. Although there was no significant difference between AC-UFH and AC-LMWH, it was found that heparin could be interacted with creatinine to enhance the adsorption capacity when compared with polyethyleneimine-modified AC. This study deepened the understanding of anticoagulation of heparinized surface and provided a theoretical basis for adsorption in hemoperfusion.