A novel wearable microbial fuel cell technology to reduce the risk of infection in wounds. The product of research at Binghamton University, State University of New York (SUNY), the living dressing also makes use of the spore-forming bacterium Bacillus subtilis, a probiotic and the chief microbe in the stringy fermented Japanese soybean dish, natto. By incorporating this beneficial bacterium into a wearable microbial fuel cell, the dressing not only generates electricity to stimulate healing but also produces antibacterial agents to combat infection. This one-two punch, that draws power from the wound’s own exudate, offers an alternative to traditional dressings and addresses the growing concern of antibiotic resistance and biofilms, which are notoriously difficult to eradicate. The dressing’s mechanism disrupts such biofilms while maintaining a balanced skin microbiome, avoiding the pitfalls of topical antibiotics in disrupting beneficial microbes that live on the skin.

The research was published in ACS Applied Materials & Interfaces.

How it works

The dressing, which is built on a wearable microfibrillated cellulose (MFC) platform, works by using Bacillus subtilis endospores as biocatalysts. The endospores, when coming into contact with wound exudate, produce electricity. This electricity serves a dual purpose: firstly, it aids in the production of antibacterial compounds by the bacteria, helping them fight off infection. Secondly, the electrical stimulation itself disrupts the cell membranes of harmful bacteria and promotes faster wound healing. The press release notes that the “electric current seems to break down the cell integrity of the infecting microbes and stimulate healing.”

“We have very [beneficial] skin bacteria that facilitate systematic immune defense. When you have a wound, this skin bacteria help with healing,” said Professor Seokheun “Sean” Choi, who led the research, in a press release. The researchers enhanced the dressing’s effectiveness through the addition of copper oxide and tin oxide nanoparticles to the spore-carrying bacteria. This addition not only boosts the dressing’s power generation capabilities but also amplifies its antibacterial properties.

“The problem is that this environment is perfect for pathogen invasion because it’s nutrient-rich, moist and warm,” Choi said. “When they start to form a biofilm, it’s really hard to eradicate those pathogens, and the wound-healing process can be extended, sometimes for a year or longer.”

“We don’t clearly understand how this electrical stimulation heals the wound infections,” Choi acknowledged. “One guess is that the membranes of a bacterial cells were damaged, but the type of electrical stimulation or how long in duration or how frequently to make it effective is something we need to study further.”

Two Ph.D. students, Maryam Rezaie and Zahra Rafiee, collaborated in the research.

Design and effectiveness

The dressing’s framework features a conductive hydrogel embedded within a paper-based substrate, ensuring cell stability and maintaining a moist environment to support healing. In lab tests, this advanced wound dressing has shown remarkable against three major wound pathogens: Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus.

The dressing also supports long-term storage as the Bacillus subtilis endospores remain dormant until the wound environment activates them.

The dressing also is sustainable as it is constructed using biodegradable papertronics.

Unlimited antibacterial production: As long as the wound exudate provides nutrients, the bacteria will continuously produce antibacterial agents, offering a sustained defense against infection. This self-powered, on-demand production surpasses the limitations of traditional dressings that rely on finite reservoirs of antibacterial agents.

While promising results have been observed in tests on simulated human skin and pig skin, further research is needed before human trials can begin. The researchers note that future study will focus on optimizing the electrical stimulation parameters, including duration and frequency, to bolster healing efficacy.