Amphiphilic biopolymers such as hydrophobically modified chitosan (hmC) have been shown to convert liquid blood as well as solutions of vesicles/liposomes into elastic gels. This interesting property could make hmC useful as a hemostatic agent in treating severe bleeding. The mechanism for blood gelling by hmC is believed to involve polymer-cell self-assembly, i.e., the insertion of hydrophobic side-chains from the polymer into the lipid membranes of blood cells, thereby creating a network of cells bridged by hmC. Here, we probe the above mechanism by studying dilute mixtures of blood cells and hmC in situ using optical microscopy. Our results show that the presence of hydrophobic side-chains on hmC induces significant clustering of blood cells. The extent of clustering was quantified from the images in terms of the area occupied by the largest clusters. Clustering increased as the fraction of hydrophobic side-chains increased; conversely, clustering was negligible in the case of the parent chitosan that had no hydrophobes. Moreover, the longer the hydrophobic side-chains, the greater the clustering (i.e., C12 &gt; C10 &gt; C8). Clustering was negligible at low hmC concentrations, but became substantial above a certain threshold. Finally, clustering due to hmC could be reversed by adding the supramolecule alpha-cyclodextrin, which is known to capture hydrophobes in its binding pocket. Overall, the results from this work are broadly consistent with the earlier mechanism, albeit with a few modifications.

Physical clotting of blood cells using associating biopolymers as the connective glue: An investigation into the mechanism using optical microscopy

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.