(29a) Biopolymer-Induced Reversible Gelation of Blood

When we suffer a wound, our body initiates the clotting cascade at the wound site, which ultimately results in a clot, i.e., a protein gel, that immobilizes blood cells. Gelation of blood is thus critical to hemostasis, i.e., the stopping of bleeding from wounds. There is a great need for a simple, yet effective hemostatic agent for use by military responders on the battlefield as well as by civilian emergency responders at the site of violent crimes or accidents. Here, we demonstrate the ability to gel blood using self-assembling biopolymers, i.e., hydrophobically modified (hm) derivatives of polysaccharides like chitosan or alginate. When such polymers are contacted with blood, they rapidly transform liquid blood into an elastic gel. Gelation occurs because the hydrophobes on polymer chains insert into the membranes of blood cells and thereby connect the cells into a sample-spanning three-dimensional network. Because the crosslinking mechanism is based on hydrophobic interactions, the addition of supramolecules with strong hydrophobic binding pockets can reverse the crosslinking and ungel the blood. Direct evidence for the above mechanism, obtained using bright-field optical microscopy, will be presented in this talk.