Lessons from the Ketchup Bottle

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Science Translational Medicine  29 Oct 2014:
Vol. 6, Issue 260, pp. 260ec188
DOI: 10.1126/scitranslmed.aaa1235

We have all encountered the stubborn ketchup bottle that refuses to give up its contents, until our growing annoyance results in a vigorous shake, causing sudden release of ketchup all over the dinner plate. This often-frustrating property of such complex solutions is known as “shear thinning”—the decrease in resistance to flow with increased shear stress. Gaharwar and colleagues have harnessed this peculiar property of complex solutions to efficiently deliver a hemostatic gel to bleeding wounds.

The authors’ hemostatic gel comprised synthetic silicate disks 2 µm in diameter and 1 nm thick. The discs were positively charged along the edge and negatively charged on the top and bottom surfaces. When combined with gelatin, which contains both positive and negative regions, the disks self-assembled via charge interactions to form structures that could dynamically form and break apart. These properties produced a gel that was thin during injection through a needle to promote ease of application but stiffened within seconds when applied to a wound. This stiffening provided a barrier to bleeding. In vitro clotting times were reduced by 77% in the presence of the gel compared with controls, including a mineral-based hemostatic agent. Coagulation proteins and blood platelets were found to spontaneously concentrate at the nanodisks, as the likely mechanism of enhanced clot formation. When injected into the soft tissue of mice, the nanocomposite gel was integrated into tissues and degraded more efficiently with less inflammatory reaction than a mineral hemostatic agent. The nanocomposite also reduced blood loss and improved survival without major side effects comparably with other hemostats when tested in a rat model of bleeding from liver injury. Further testing in high-pressure bleeding models is required to fully define the hemostatic capabilities of this nanocomposite gel. But, perhaps one day these lessons first learned at the dinner table can be translated to new therapies to stop bleeding.

A. K.Gaharwar et al., Shear-thinning nanocomposite hydrogels for the treatment of hemorrhage. ACS Nano, published online 8 October (2014). [Abstract]

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