Researchers at the Terasaki Institute for Biomedical Innovation in California have developed an implantable sponge that can monitor for signs of a hemorrhage, and then help to control bleeding once it has occurred. The researchers used silk fibroin, a protein produced by the Bombyx mori silkworm, to create the sponge, and took advantage of its biodegradation and anti-inflammatory properties to create a porous and highly absorbent shape-memory sponge. The sponge also contains two layers of silver nanowires above and below the sponge layer which deliver anti-bacterial action and serve as a hemorrhage monitoring system. The wires act as capacitance sensors, whereby the capacitance increases as the sponge absorbs blood.
There are many different approaches to stem bleeding, including bandages and tourniquets, but many of these are suitable only for external wounds that are amenable to compression. For irregular wounds or internal wounds, such solutions may not work so easily. One option is the shape-memory sponge. When applied to a wound it absorbs blood, helping to promote coagulation, and also applies pressure to the underlying wound as it swells with blood.
However, existing sponges for this application, such as those made using collagen or gelatin, are purely mechanical and cannot alert clinicians to the emergence of a hemorrhage. However, they can help to stop the bleeding and usually incorporate biodegradable materials so that they may not require removal through a second surgical procedure if implanted internally. These researchers wished to take this concept one step further and incorporate a system that would alert them to the presence of a hemorrhage.
Their sponge contains silver nanowires that form capacitive sensors that produce a measurable electric signal when the sponge becomes filled with blood. Moreover, the silver in the wires also provides an anti-microbial effect to help ward off infections. The researchers have also been able to tune the biodegradation and mechanical properties of the sponge to suit different clinical scenarios.
“This multifunctional device offers many attractive features for hemorrhage control and wound monitoring and is highly adaptable for different types of wounds and tissues,” said Ali Khademhossein, one of the lead scientists that developed the new sponge. “And the hemorrhage monitoring feature also opens up several possibilities for integrative biosensing and additional therapeutics.”
Study in journal Advanced Science: An All‐In‐One Transient Theranostic Platform for Intelligent Management of Hemorrhage