The durable coating, which could be a game changer in traditionally germ-laden public spaces like hospitals and airports, killed 99.9% of germs even after months of repeated cleaning and abrasion on real-world surfaces, including keyboards, mobile phone screen and chicken-slotted cutting boards.
Anish Tuteja, a professor at the University of Michigan, said disinfectant cleaners can kill germs in just a minute or two, but they destroy quickly and leave surfaces vulnerable to reinfection.
“We have long-lasting antibacterial surfaces based on metals like copper and zinc, but they take hours to kill bacteria. This coating provides the best of both worlds,” said Tuteja, who co-corresponds to the research published in are authors. Journal Matter, noted.
Coating uses antimicrobial molecules
The researchers further said that the coating, which is clear and can be brushed or sprayed on, uses antimicrobial molecules extracted from tea tree oil and cinnamon oil.
Both of these derivatives have been used for centuries as safe and effective germ killer Which works in less than two minutes.
The durability of the coating comes from polyurethane, a tough, varnish-like sealer often used on surfaces such as floors and furniture.
“The antimicrobial drugs we tested are classified as ‘generally recognized as safe’ by the FDA, and some have even been approved as food additives,” Tuteja said.
“Polyurethane is a safe and commonly used coating. But we did toxicity testing just to be sure, and we found that our particular combination of ingredients is even safer than many of today’s antimicrobials,” he explained.
The coating can kill germs for 6 months/longer
The results of the study’s durability tests proposed that the coating could kill germs for six months or more, before its oil evaporates and its disinfectant power diminishes.
However, even then, Tuteja said it can be recharged by wiping it with fresh oil, which is reabsorbed by the surface, starting the cycle all over again.
He estimates that the technology could be commercially available within 365 days.
The main challenge in creating the coating was to mix the oil and polyurethane in such a way that the oil molecules could perform their germ-killing work, while preventing them from evaporating too quickly.
It has been licensed to Hygretech, a spinoff company that Tuteja founded with the help of an innovation partnership from the University of Michigan.
The team, including associate professor Geeta Mehta, and materials science and engineering PhD students Abhishek Dhyani and Taylor Repetto, found a possible solution in cross-linking, a well-known process that uses heating to link materials together at the molecular level.
The small oil molecules form a stable matrix by easily cross-linking polymer molecules together, the researchers said.
However, in order to kill germs, oil molecules have to penetrate their cell walls, which they cannot do if they are tightly bound in the matrix.
Eventually, they found a middle ground by partially cross-linking the material—enough to keep some molecules free to do their jobs, but keep others tightly bound to the polyurethane.
“There was some trial and error, but we eventually found that cross-linking just some of the oil did what we needed,” Tuteja said.
“The free oil stays in with the oil that’s cross-linked in the matrix, helping the coating last longer,” he said.
Once the basic recipe was determined, the researchers set about finding a combination of active ingredients that would kill a variety of germs that most bother humans.
To identify a representative sample of microbes, the team found a precise balance of antimicrobial molecules that were effective, safe and cheap.
He said the team’s understanding of the properties of individual ingredients enables them to alter the formula for specific applications or to rebalance antimicrobial agents to kill specific microbes.
Tuteja continued, “Our goal is not to develop just a one-time coating, but instead to develop a library of underlying physical properties.”
“If we can understand those properties, we can develop coatings to meet the needs of specific applications,” Tuteja said.
with agency input
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