Rutgers team develops method of killing bacteria with devices made of paper
Inspired by the 2014 Ebola outbreak in Sierra Leone, researchers at Rutgers have been developing plasma sanitizers based on paper, which can have implications towards the future of antimicrobial protection.
The sanitizers involve metallized paper, which is composed of coated plant fibers, a thin layer of aluminum and an insulating polymer, or synthetic substance, on top, said Aaron Mazzeo, a professor in the Department of Mechanical and Aerospace Engineering.
“Metallized paper is a commercially-available material. Often, it’s the shiny material that you see on a beverage or even a can of beans, and then they print on top of it so it’s a metallized, glossy-looking paper,” he said.
The research team, composed of graduate students and professors from both the Department of Plant Biology and the Department of Mechanical and Aerospace Engineering, would use a laser to remove some of the metal. They would then put electrical “traces” into the metallized paper.
The surface would thus not be completely conductive to electricity, but instead have distinct regions that are conductive. These specific regions are then able to create plasma when a high-enough electricity is applied.
By using flexible materials such as paper, Mazzeo said it could mark a potential path toward devices that could be inserted into locations or even be worn as a patch by people. Another benefit of using paper is its low cost and low impact on the environment, because the generators required to put traces in the metallized paper do not require fuel or added chemicals.
“They use the air around us. They do require high-voltage and electricity, but it’s not like you have to fill a little alcohol patch or something for it to be to be able to deactivate the bacteria,” Mazzeo said.
He also added that the paper was porous, meaning it had holes where air could pass. A possible advantage of a porous material may be that the plasma may be fueled more efficiently, he said. The production of plasma is important because it can be a promising and effective way to kill microbes or undesirable bacteria such as E. coli.
The plasma has been reported to sanitize at least 99 percent of bacteria, but the goal is to sterilize 99.9999 percent, which requires more microbes to be deactivated. As a result, the team is also currently conducting tests on how to kill spores, or bacteria in a dormant state.
“Spore formation, in simple terms, is a survival strategy of organisms in unfavorable conditions. Spore-forming organisms are resistant to common sterilization treatments such as heat, chemicals, radiation, osmosis, and desiccation,” said Ramendra Pal, a postdoctoral associate in the research group. “The resistance of spores in food leads to spoilage and foodborne diseases.”
Pal said while the exact mechanism for how cold plasma deactivated bacteria was unclear, factors such as UV radiation and reactive species created in cold plasma work together to deactivate them.
As for what their research will possibly be used for, some possibilities were food preservation and sanitization. Pal said the hope is to develop plasma generators which can sanitize a fruit or vegetable, and with enough progress — self-sanitized food packaging.
“The second direction will lead to wearable patches that generate plasma to kill wound bacteria. This approach can treat both acute and chronic wounds, and reduce hospital stays by bringing parts of the treatment at home,” Pal said.
Despite the breakthroughs and progress made over the years, Mazzeo said his team still has more research to undergo.
“We’re still doing work. We still don’t know the full impact or capabilities. It’s science. We do something kind of interesting, and we try to figure out what the end-application will be, but the production of the plasma is potentially an effective way to kill microbes,” Mazzeo said.