Reversible Gelation of Vesicles and Blood

S.R. Raghavan, M.B. Dowling, V. Javvaji
University of Maryland, US

Keywords: gelation, self-assembly, hemostatic biomaterials

Summary:

This talk will discuss the action of polymers with hydrophobic stickers on various nano or microstructures. In particular, we have used a hydrophobically modified (hm) derivative of the polysaccharide, chitosan. When hm-chitosan is combined with a solution of vesicles, the vesicles are connected by polymer chains into a three-dimensional gel network that exhibits elastic rheology. In contrast, the native polymer (without hydrophobes) does not produce a gel. Similar gelation due to hm-chitosan also occurs for biological cells, including blood. The ability to gel blood implies the use of hm-chitosan as a hemostatic agent, i.e., to arrest bleeding from serious wounds. Indeed, experiments with animal models confirm the hemostatic ability of this polymer. It is also useful to have the capability of reversing the polymer-induced gelation. We have found that gelation can be reversed by the addition of alpha-cyclodextrin, a sugar-based supramolecule with a hydrophobic binding pocket. Overall, the scheme for reversible gelation discussed here is likely to prove useful in a variety of applications.