Wearable Sensor Detects Presymptomatic Bacterial Infections in Diabetic Foot Ulcer Swabs, Mice

By Marilynn Larkin

November 29, 2021

NEW YORK (Reuters Health) - A novel wearable DNA hydrogel-based sensor detected bacterial infections in swabs from diabetic foot ulcers and in infected wounds in mice before visible infection, researchers say.

"Our next step is to study the performance of the sensor in a clinical trial to rigorously validate its sensitivity and specificity," Drs. John Ho and Ze Xiong of the National University of Singapore told Reuters Health by email. "We are also planning to expand the functionality of the sensor to measure additional parameters, such as temperature or pH, to further improve its accuracy."

Further, they said, "Before directly applying our sensor on patients, we will need to perform more tests to prove that the hydrogel is not toxic and study its response to other strains of bacteria."

"Another technical obstacle is that the DNA hydrogel will dry out over time, which limits the length of time that the sensor can work," he noted. "We are exploring ways to extend its lifetime to cover use cases where the sensor may need to monitor the wound for up to two weeks."

As reported in Science Advances, the team developed a flexible, wireless, battery-free sensor that provides smartphone-based detection of wound infection using a bacteria-responsive DNA hydrogel.

First, they evaluated the hydrogel's ability to detect S. aureus infection in wound swabs collected from 18 patients with diabetic foot ulcers, three of which were known to be positive for the bacterium. The fluorescence intensity of the stained hydrogel decreased by 52% when exposed to the infected samples but by less than 27% when exposed to control swabs. According to the authors, this indicates that the gel degrades in the presence of S. aureus with minimal interference from harmless microbes.

Next, they tested the sensor's ability to detect wound infections in mice. Although the infected and uninfected wounds looked the same at 24 hours, the sensor detected a 0.4-volt signal change in the infected wounds, which triggered an alert that was sent to a smartphone app. This showed that the sensor could detect physiologically relevant amounts of S. aureus even before visible infection.

Drs. Ho and Xiong added, "Low-cost, smartphone readable sensors could soon empower patients to monitor their wound for infections and seek timely treatment. These sensors, which combine advances in materials science and wireless technology, can be placed under wound dressings and be used by simply 'tapping' your phone over the dressing. The total cost of the sensor is less than $5."

Dr. Wei Gao, Assistant Professor of Medical Engineering at California Institute of Technology in Pasadena, commented in an email to Reuters Health, "Successful implementation of this technology in clinical settings can significantly improve the clinical management of infected wounds."

"Future work could focus on technological developments to provide additional capabilities for wound care," he said. "For example, in addition to detecting infection, quantitative assessment of infection severity could be valuable in helping to determine the appropriate treatment at the point of care."

"One aspect is to combine this technology with existing sensors such as temperature, moisture, oxygen and pH and inflammatory biomarkers sensors for a multiplexed analysis of the wound microenvironment," he suggested. "Another aspect is integrating this hydrogel system into drug- loaded biomaterials to enable local and effective drug delivery of particular antimicrobial agents."

Like Drs. Ho and Xiong, he noted, "For clinical applications, the sensor can be further modified and embedded into wound dressings to enable patients to monitor their wounds between clinical assessments and seek appropriate interventions if infection is detected."

"In addition, this technology can be coupled with antimicrobial dressings/gels to not only detect, but also combat the wound infection," he said. "Large-scale production could facilitate smart and dynamic chronic wound management."

SOURCE: https://bit.ly/3oZLJ88 Science Advances, online November 19, 2021.