| Summary: | Enhancement of hemostasis at the site of wound is a very attractive method to limit
bleeding and to reduce the need for blood transfusion support. However, many commercially
available bioadhesives and hemostatic agents fail to fulfill the design requirements of efficacy,
safety and cost. There is a need to develop novel bioadhesive and hemostatic agents that would
overcome these limitations.
A library of hyperbranched polyglycerol (HPG) based macromolecular structures
functionalized with different mole fractions of zwitterionic sulfabetaine and cationic quaternary
ammonium ligands were synthesized and characterized. A post-polymerization method was
employed that utilized double bond moieties on the HPG backbone for the coupling of thiolcapped
functional groups via UV initiated thiol-ene “click” chemistry. The proportions of
different ligands were precisely controlled by varying the monomer concentration during the
irradiation process.
The effect of the polymer on hemostasis has been investigated using whole blood. It was
found that polymer with 40% or more positive charged groups caused hemagglutination without
causing red blood cell lysis. The quaternary ammonium groups can interact with the negative
charged sites on the membranes of erythrocytes, which improves the bioadhesiveness. The
zwitterionic sulfabetaine can provide a hydration layer to partially mask the adverse effects that
are likely to be caused by cationic moieties on the integrity of cell membrane. The conjugate was
also found to be able to enhance platelet aggregation and activation in a concentration and
positive charge density dependent manner, which would contribute to the initiation of
hemostasis. The polymer-induced hemostasis is obtained by a process independent of the normal
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blood coagulation cascade but dependent on red blood cell agglutination, where the polymers
promote hemostasis by linking erythrocytes together to form a lattice to entrap the cells. === Science, Faculty of === Chemistry, Department of === Graduate
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