Synthesis and Characterization of Hemostatic Foams

Hydrophobically modified (hm) derivatives of biopolymers like chitosan have the ability to coagulate blood cells and thus stop bleeding from severe injuries (i.e., achieve hemostasis). Our lab has been particularly interested in developing foams based on these polymers for use as hemostastic agents. Foams are attractive because an expanding foam at a wound site can counteract blood loss without the need for mechanical compression. The amphiphilic nature of hm-polymers also enables them to stabilize such foams. Previous work centered around a foam based on hm-chitosan (hmC) that was delivered out of a canister. To effectively combat internal hemorrhaging, we recognized the need to develop foams that could be more precisely placed at the wound site and also had greater mechanical integrity. Towards this end, this thesis describes a new class of polymeric foams that can be delivered out of a double-barreled syringe (DBS) by combining precursors in the two barrels that produce bubbles of CO2 gas in situ. Moreover, we show that by combining hmC in one barrel with a second biopolymer – hm-alginate (hmA) – in the other, we can generate foams with enhanced rheological properties compared to foams of hmC alone. This rheological enhancement is quantified in our work, and is due to electrostatic interactions between the cationic hmC and the anionic hmA chains. Preliminary studies in animal wound models also confirm that hmC-hmA foams can be precisely directed to a wound using the DBS and that these foams form effective barriers to blood loss due to their greater mechanical integrity