Researchers in the University of Toronto's Faculty of Applied Science & Engineering have developed a non-toxic coating that can prevent proteins from sticking to surfaces, potentially offering a new tool in the fight against hospital-acquired infections.
For the study, a team led by Kevin Golovin, an assistant professor in the department of mechanical and industrial engineering, examined whether a "molecular brush" coating of polydimethylsiloxane (PDMS) - a type of silicone polymer - could prevent proteins from adhering to surfaces.
They found the PDMS brush repelled proteins and outperformed other materials, suggesting it could help prevent infectious bacteria from gaining a foothold on medical devices. The research was published in Chemical Engineering Journal .
"Many infectious diseases are transmitted by touch," said Golovin, who heads the Durable Repellent Engineered Advanced Materials (DREAM) Laboratory . "The microbes that carry them typically release a sticky layer of proteins that enable their attachment to a surface. If you can stop those proteins from sticking, you can stop the disease from spreading."
Golovin and his team are experts in designing surface coatings that selectively repel certain substances. Their work has a range of applications, from keeping airplane wings ice-free to designing new types of non-stick cookware .
"Right now, the simplest way to keep a surface clean and free of disease-causing microbes is to wash it with disinfectants like bleach," said Golovin. "But of course, it's not great for the humans that work in these environments to be constantly exposed to these toxic products. And any time you're using chemicals to kill pathogens, you're increasing the chance of some strain evolving to be immune to them."
Golovin's team has worked extensively with PDMS, a silicone polymer that is flexible, transparent and biocompatible. It is already widely used in medical applications that range from contact lenses to breast implants.
Although PDMS naturally repels bacteria to some degree, the team believed they could supercharge its ability to do so by altering its molecular structure.
"One way to use PDMS is to cross-link the polymer chains together into a bulk solid, which is the common material known as silicone rubber," said PhD student Mehdi Sadeghi, lead author on the new paper. "But our surface is different: instead of having interconnected, solidified chains, it's instead covered in long chains of PDMS that stick out from the surface - like the bristles on a brush."
But unlike brush bristles, these PDMS chains aren't very stiff: they can bend and sway, giving rise to a surface that the team describes as "liquid-like." This makes it difficult for the sticky proteins secreted by bacteria to get a good grip.
To test their surface, the team used bovine serum albumen (BSA), a model protein derived from cow's blood, to serve as a proxy for bacterial proteins.
They placed droplets of BSA dissolved in salt water on their surface, as well as surfaces treated with other non-stick coatings.
"As the droplet evaporates, what you normally see is that the BSA moves to the edges, forming something that looks like a coffee ring - a dark ring that stays behind on the surface even after all the water is gone," said Sadeghi. "But on the liquid-like surface covered in PDMS bristles, we didn't see that. Instead, the ring shrunk along with the droplet, because the proteins just couldn't stick.
"All you're left with at the end is a small dot of residue that just flakes off at the slightest touch: even a small puff of air is enough to make it fly off the surface. You could also wash it off with plain water, rather than harsh chemicals like bleach."
In the team's tests, the PDMS bristles resisted protein adhesion even better than polyfluoroalkyl substances (PFAS), a family of chemicals that includes the famously non-stick Teflon.
Given that exposure to high levels of PFAS chemicals has been linked to health effects such as cancer, PDMS bristles could offer a safer solution.
Golovin said the team's next steps will include partnering with researchers who study pathogenic bacteria to confirm whether their surface is able to repel real adhesive proteins as well as it does BSA. They're also working with companies who manufacture medical equipment and might wish to license or commercialize the technology.
The research was partly funded by Meltech Innovation Canada Inc., part of the Medicom Group. Based in Sainte-Eustache, Que., the company is a leading global producer of infection control products.
Nektaria Markoglou, vice-president, scientific affairs and head of the R&D department at Meltech, said the DREAM Lab's research is enabling new insights into how contaminants interact with materials. "By supporting early-stage research, we are enabling the development of more sophisticated and resilient protective solutions designed to better safeguard patients and health-care professionals," Markoglou said.
Golovin noted the PDMS coating process is scalable and that large-scale deployment "will depend on optimizing manufacturing integration.
"Further assessment will be required to identify cost-effective pathways that align with the significant protective performance this technology enables, supporting potential expansion into both high-value equipment and single-use products," Golovin said. "We're very excited about the future possibilities."
