After a serious injury, few challenges are more urgent than stopping life-threatening bleeding. Biodegradable microparticles that combine to form a gel on a wound offer significant improvements over existing alternatives. Deepa Ghosh and colleagues at the Institute of Nano Science and Technology in Punjab, India, report on their success in the early-stage development of the starch-based “hemostat” material in the journal Materialia.

“Presently, no single hemostatic agent exists that can work in all situations,” says Ghosh, explaining the motivation driving the research. She adds that current hemostat materials are very expensive and available mostly in developed countries. Together with her colleagues, Ghosh hopes to develop a versatile, potentially life-saving and inexpensive product that would be a more realistic solution for lower-income economies worldwide.

By physically absorbing excess fluid, hemostat materials concentrate the natural clotting factors in blood that are critical for stopping the blood flow; however, the bleeding can restart when non-biodegradable materials are removed. Ghosh says that a few starch-based biodegradable options are currently available, but they are limited by their relatively slow fluid absorption and poor adhesion to wounded tissues. Other problems include the rigidity of current options and safety issues focused on imperfect biocompatibility.

By chemically modifying natural starch to form microparticles, Ghosh’s team have combined the advantages of biocompatibility and biodegradability with a five- to ten-fold increase in fluid absorption and much improved adhesion. When the microparticles combine, they create an adherent gel that can remain on the wound until slowly dissipating as healing proceeds.

The new material is also rich in calcium ions, which encourage the aggregation of red blood cells and platelets and their activation to generate the fibrin protein network that forms a stable blood clot.

The micro particles are prepared by modifying some of the chemical hydroxyl groups on starch to carboxymethyl groups while also incorporating the beneficial calcium ions. The modification increases the ability of the molecules to interact with water. This is the basis of its impressive ability to absorb fluid from the blood and hence concentrate the clotting factors.

In lab tests, the microparticles of the product, known as 'calcium-modified carboxymethyl-starch', swelled up to form a cohesive and adherent gel within 30 seconds after contact with blood.

In animal studies with real wounds, moderate to heavy blood flow was stopped in less than one minute. The animal studies also indicate that the material is non-toxic and confirmed its biodegradability.

“These encouraging results suggest our modified starch microparticles are a very promising candidate for further exploration in clinical applications,” Ghosh concludes.

Article details:

Ghosh, D. et al.: “In-vitro and In-vivo evaluation of biocompatible and biodegradable calcium-modified carboxymethyl starch as a topical hemostat” Materialia (2019)

Materialia is part of the family of Acta Materialia Inc journals, which also includes Acta MaterialiaScripta Materialia and Acta Biomaterialia.

Schematic illustration of the hemostatic mechanism of modified starch micro particles
Schematic illustration of the hemostatic mechanism of modified starch micro particles