Color-changing sutures could revolutionize infection detection

Surgeries are always accompanied by a lingering shadow of concern: postoperative complications—most commonly surgical site infections (SSIs) and wound dehiscence.

This is why scientists are actively investigating innovative approaches to develop advanced sutures that can do much more than hold together the edges of a surgical incision or wound. But they’re not the only ones tackling the SSI issue in the lab.

A young scientist’s color-changing sutures

In 2019, when she was just 17, Dasia Taylor developed novel, color-changing sutures during her 11th grade at Iowa City West High School. She was profiled in Smithsonian Magazine,^[] and her sutures gained recognition by winning top honors at regional and international science fairs.

Taylor’s special sutures change color when they get infected, giving doctors a clear sign to take action quickly.

Traditionally, surgical sutures have been coated with antibiotics such as triclosan to potentially ward off SSIs, but their effectiveness is waning in the face of mounting antibiotic resistance, according to the authors of an article in Scientific Reports.^[]

Taylor’s research revealed that sutures coated in beetroot juice changed color from bright red to dark purple following 5 minutes of exposure to a pH close to that of an infection (normal human skin has an acidic pH of around 5, while infected wounds have a higher pH of about 9). “I found that beets changed color at the perfect pH point,” Taylor told Smithsonian. Bright-red beet juice turns dark purple at a pH of 9. “That's perfect for an infected wound. And so, I was like, ‘Oh, okay. So beets is where it's at,’” she said.

But the color-changing infection-detection properties aren’t the only benefit of Taylor’s sutures. Further testing on K-12 E. coli-treated Petri dishes indicated that the beet juice suture possessed antibacterial properties. The presence of beet juice prevented the growth of K-12 E. coli in the Petri dish.^[]

The cost of managing SSIs

Taylor is currently seeking a patent for her revolutionary sutures. The application process could take time, but if the patent is approved, Taylor plans to continue her research and work toward providing these sutures to people in developing countries.

In the US alone, the cost of managing SSIs and their associated complications is estimated to range from $3.5 billion to $10 billion annually, according to the Scientific Reports authors.

Smart sutures are showing promise against the most common types of postoperative complications, but cost has made these inaccessible to some patients—something Taylor's color-changing sutures aim to address. Here are some other examples of smart sutures:

• Researchers from Singapore have developed smart electronic sutures capable of wirelessly monitoring surgical wounds using a small electronic sensor and a conductive polymer coating.^[] The stitches act as radio-frequency identification (RFID) and can detect abnormal changes in the healing wound.

• Smart sutures developed at the University of Illinois incorporate ultrathin silicon sensors, which accurately detect infection-related elevated temperatures, reported by MIT Technology Review.^[] These sutures are also able to deliver controlled heat to the wound for faster healing.

• Metallic nanoparticle (MNP)-coated sutures, as noted by Scientific Reports, have demonstrated effectiveness against common SSIs-causing bacteria, such as Pseudomonas aeruginosa and Staphylococcus aureus.

• Nonthermal atmospheric plasma-treated sutures prevent bacterial colonization of S. aureus and Escherichia coli over surgical sites, according to research published in PLOS One.^[]

Not only does Taylor’s innovative solution have the potential to revolutionize healthcare, but it also earned her recognition as one of USA TODAY's Women of the Year. In a profile, Taylor said that her invention stemmed from her commitment to equity, driven by the disproportionate impact of post-surgical issues on Black individuals.^[]

Limitations and challenges of Taylor’s sutures

As noted by the Smithsonian article, critics argue these threads need to surpass the standards of conventional sutures in terms of biocompatibility, nonreactivity, robustness, and promotion of wound healing to remain competitive. 

One drawback is their limited ability to detect infections beneath the skin, especially in cases like cesarean sections, where infections can develop beneath the surface before becoming visible—at which point the infection may be advanced. 

The non-absorbent nature of standard sutures, while challenging for color application with beetroot, provides a barrier against bacteria. Taylor's cotton-polyester blend thread, for example, dyes easily but could harbor bacteria. Balancing Taylor’s thread's color-changing properties with its ability to block bacteria would be crucial for further improvement. Nevertheless, this ingenious invention is a significant breakthrough in infection detection.