Numerous products exist for controlling hemorrhages such as cotton or gauze bandages, powders, and tourniquets. These are typically used for shallow wounds of uniform shape, however, they lack the ability to simultaneously detect bleeding and control hemorrhage. Recent advancements have introduced shape-memory sponges that are highly absorbent and retain their structure even when treating deep, irregularly shaped wounds, facilitating blood coagulation. While cellulose-based shape-memory sponges are effective, they aren't biodegradable unlike their gelatin-based counterparts, and both lack hemorrhage detection capabilities. Now, scientists have engineered a multi-purpose device for treating deep, non-compressible, and irregularly-shaped wounds. This device offers prompt hemorrhage management, minimal inflammation, infection control, adjustable biodegradation rates for both internal and external use, and sensing capabilities for long-term hemorrhage tracking. This device can be valuable for timely alerts and managing bleeding from surgical wounds, traumatic injuries, and critical illnesses.

Scientists at the Terasaki Institute (Los Angeles, CA, USA) created the innovative hemorrhage management device using silk fibroin, a protein from the Bombyx mori silkworm. This biodegradable material possesses excellent anti-inflammatory and mechanical properties and can be engineered into highly absorbent, porous, memory-shaped sponges that promote coagulation and tissue regeneration. The adjustable degradation rates of these sponges allow for longer in-body use and the potential to incorporate sensors for monitoring bleeding. Leveraging these capabilities, the scientists designed a unique, all-in-one hemorrhage management device that integrates two silver nanowire layers positioned above and a hemostatic sponge layer below which serve as hemorrhage detection sensors and antibacterial agents.

The device underwent a thorough evaluation, including tests for mechanical properties, biocompatibility, and biodegradation. Mechanically, the silk fibroin sponges demonstrated excellent elasticity, absorptive capacity, and high retention of pore size and shape against water and blood exposure, along with maximum hemorrhage control achieved by adjusting silk fibroin concentrations to match the mechanical properties of the surrounding wound tissue. The sponge and nanowire layers demonstrated favorable biocompatibility and minimal anti-inflammatory responses, as proven by the successful cell viability and proliferation tests using connective tissue samples. Further testing indicated that the sponge’s degradation rate could be slowed by increasing the silk fibroin concentration and incorporating a methanol wash step during the manufacturing process.

Following this evaluation, the device and a commercial gelatin-based anti-hemorrhage device were implanted under the skin in rat models for comparison. After four weeks, the commercial sponge had completely degraded while the silk fibroin nanowire device remained intact. The implanted sponge triggered minimal inflammation and had no negative impact on the rats' organs or behavior. Moreover, the silk fibroin device surpassed the commercial sponge in hemorrhage control tests, offering double the level of hemorrhage control in a rat bleeding model. In addition to managing hemorrhage, the device features a nanowire-based capacitive sensor for detecting bleeding. As the sponge absorbs blood during bleeding, its capacitance increases without any change in shape. This increase in capacitance is measurable and directly corresponds to the amount of absorbed blood, thereby enabling real-time bleeding monitoring. Testing demonstrated that the device could selectively monitor blood absorption against other body fluids which it may come into contact with in the wound.

“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, Ph.D., TIBI’s Director and CEO. “And the hemorrhage monitoring feature also opens up several possibilities for integrative biosensing and additional therapeutics.” 

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