How to stop leaks — the way blood does

When you get a cut, blood starts to flow from the wound. But very quickly, complex biochemical processes spring into action, creating a scaffolding of molecules to block the hole, and then building up an impervious clot to stanch the flow.

That process relies on a set of molecules that constantly flow through the body's veins and arteries, just waiting to spring into action when needed. When their job is done, they dissolve back into the blood, awaiting their next repair job.

A team of MIT researchers has analysed the process and found, for the first time, exactly how the different molecular components work together to block the flow of blood from a cut. Now, they are working on applying that knowledge to the development of synthetic materials that could be used to control different kinds of liquid flows, and could lead to a variety of new self-assembling materials.

The research is published this week in the online journal Nature Communications, in a paper co-authored by MIT assistant professor of materials science and engineering Alfredo Alexander-Katz, graduate student Hsieh Chen, and six other researchers in the United States, Germany and Austria.

One of the surprising things the team found out is that the increased flow rate caused by a wound automatically triggers the reaction that plugs the hole: The faster the flow, the more effectively it works. That's a counterintuitive finding, since faster flows usually stir things up rather than causing them to clump together.

The way the molecules in the bloodstream react to a leak ''is something very freaky,'' Alexander-Katz says. ''Part of it is chemistry, and part of it is mechanical, which has to do with the flow itself.''