Stopping excessive blood loss with a bandage covered in microneedles

Chemical and biomedical engineers have designed a new type of bandage that can stop uncontrolled bleeding from a traumatic injury almost immediately.

The prototype patch uses haemostatic microneedle technology – biocompatible and biodegradable microneedle arrays (MNAs) – that increase its surface contact with blood to accelerate the clotting process.

“Excessive bleeding is a serious challenge for human health,” says Amir Sheikhi, Assistant Professor of Chemical Engineering and of Biomedical Engineering at the Pennsylvania State University in the US who was involved in the research.

“With haemorrhaging injuries, it is often the loss of blood — not the injury itself — that causes death. There is an unmet medical need for ready-to-use biomaterials that promote rapid blood coagulation.”

The patch’s adhesive properties are enhanced through the interlocking that occurs between the microneedles and the tissue, which also promotes wound closure.

Read more: 3D printed microneedles that dissolve in the skin.

“In vitro, the engineered MNAs reduced clotting time from 11.5 minutes to 1.3 minutes; and in a rat liver bleeding model, they reduced bleeding by more than 90%,” Sheikhi says.

“Those 10 minutes could be the difference between life and death.”

Composite image of diagrams and photographs of the microneedle array fabrication process
Fabrication of hemostatic microneedle arrays (MNAs). (a) Schematic of MNA fabrication steps, including casting a dispersion of GelMA matrix and SN fillers in microneedle molds. Ultraviolet (UV) light-mediated photocrosslinking yields a chemically crosslinked hydrogel, which is dried and peeled off. (b) Graphical representation of facile MNA application onto a bleeding model to stop hemorrhage. (c) An image of fabricated MNAs, comprising 11 × 11 microneedles. (d) Brightfield image bottom view of MNAs. (e) Scanning electron microscopy (SEM) images of MNAs showing a height of ∼577 μm and a base width of ∼308 μm. Credit: DOI:10.1016/j.bioactmat.2022.08.017

The microneedles are made from a gelatine methacryloyl (GelMA) hydrogel material with silicate nanoplatelets (SNs) using a commercial pre-made mould. The disc shaped SNs, which have a diameter of about 30 nanometres and thickness of only 1nm, have negative charges on their surfaces and positive charges on their edge.

Read more: A snake venom-based first-aid gel could become the saviour of accident victims experiencing uncontrolled bleeding.

Psn amir lab 850
Amir Sheikhi, assistant professor of chemical engineering and of biomedical engineering at Penn State, developed a prototype of a microneedle patch that can immediately stop bleeding after injury. Credit: Kelby Hochreither/Penn State

It’s thought that these electrostatic charges result in the aggregation of platelets and the activation of coagulation factors in the blood, which may eventually trigger the coagulation cascade – the process through which blood clots.

The microneedles, which are already used in other applications to deliver biologics like cells or drugs or to stimulate collagen production in cosmetic procedures, are so tiny (just over half a millimetre tall) that applying them is completely pain free.

And although it may sound high-tech, the MNA patch is designed to be prefabricated and ready for immediate use – much like a typical over-the-counter adhesive bandage.

The authors have plans to further test the technology and are working to translate the prototype from the lab to the market.

“These haemostatic MNAs may enable rapid haemorrhage control, particularly for patients in developing countries, or remote areas with limited or no immediate access to hospitals,” they write in the journal Bioactive Materials.

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