Surgical stitches that generate electricity can help wounds heal faster in rats, a new study from China finds.
In the body, electricity helps the heart beat, causes muscles to contract, and enables the body to communicate with the brain. Now scientists are increasingly using electricity to promote healing with so-called electroceuticals. These electrotherapies often seek to mimic the electrical signals the body naturally uses to help new cells migrate to wounds to support the healing process.
In the new study, researchers focused on sutures, which are used to close wounds and surgical incisions. Despite the way in which medical devices have evolved rapidly over the years, sutures are generally limited in capability, says Zhouquan Sun, a doctoral candidate at Donghua University in Shanghai. “This observation led us to explore integrating advanced therapeutics into sutures,” Sun says.
Prior work sought to enhance sutures by adding drugs or growth factors to the stitches. However, most of these drugs either had insignificant effects on healing, or triggered side-effects such as allergic reactions or nausea. Growth factors in sutures often degraded before they could have any effect, or failed to activate entirely.
The research team that created the new sutures previously developed fibers for electronics for nearly 10 years for applications such as sensors. “This is our first attempt to apply fiber electronics in the biomedical field,” says Chengyi Hou, a professor of materials science and engineering at Donghua University.
Making Electrical Sutures Work
The new sutures are roughly 500 microns wide, or about five times the width of the average human hair. Like typical sutures, the new stitches are biodegradable, avoiding the need for doctors to remove the stitches and potentially cause more damage to a wound.
Each suture is made of a magnesium filament core wrapped in poly(lactic-co-glycolic) acid (PLGA) nanofibers, a commercially available, inexpensive, biodegradable polymer used in sutures. The suture also includes an outer sheath made of polycaprolactone (PCL), a biodegradable polyester and another common suture material.
Previously, electrotherapy devices were often bulky and expensive, and required wires connected to an external battery. The new stitches are instead powered by the triboelectric effect, the most common cause of static electricity. When two different materials repeatedly touch and then separate—in the case of the new suture, its core and sheath—the surface of one material can steal electrons from the surface of the other. This is why rubbing feet on a carpet or a running a comb through hair can build up electric charge.
A common problem sutures face is how daily movements may cause strain that reduce their efficacy. The new stitches take advantage of these motions to help generate electricity that helps wounds heal.
The main obstacle the researchers had to surmount was developing a suture that was both thin and strong enough to serve in medicine. Over the course of nearly two years, they tinkered with the molecular weights of the polymers they used and refined their fiber spinning technology to reduce their suture’s diameter while maintaining strength, Sun says.
In lab experiments on rats, the sutures generated about 2.3 volts during normal exercise. The scientists found the new sutures could speed up wound healing by 50 percent over the course of 10 days compared to conventional sutures. They also significantly lowered bacteria levels even without the use of daily wound disinfectants, suggesting they could reduce the risk of post-operation infections.
“Future research may delve deeper into the molecular mechanisms of how electrical stimulation facilitated would healing,” says Hui Wang, a chief physician at Shanghai Sixth People’s Hospital.
Further tests are needed in clinical settings to assess how effective these sutures are in humans. If such experiments prove successful, “this bioabsorbable electrically stimulating suture could change how we treat injuries in the future,” Hou says.
The scientists detailed their findings online 8 October in the journal Nature Communications.
Charles Q. Choi is a science reporter who contributes regularly to IEEE Spectrum. He has written for Scientific American, The New York Times, Wired, and Science, among others.
