Oil-exuding silicone could prevent bacterial infections

Bacterial biofilm formation on the right side of medical tubing is visible after being stained, whereas the treated section of the tubing on the left remains biofilm-free (Photo: Wyss Institute at Harvard University)

Whenever foreign objects such as catheters, implants or other devices are placed within the human body, there's a danger that bacterial colonies known as biofilms could collect on them, leading to infections. Now, however, scientists at Harvard University's Wyss Institute have created a material that's too slippery for those biofilms to cling onto. It works by continuously releasing oil.

Led by Prof. Joanna Aizenberg, the team is developing what are referred to as liquid-infused polymers. The technology takes advantage of the loose molecular structure of polymers, which allows them to take up and store large amounts of liquid lubricants. Those lubricants diffuse to the surface of the polymer, where they keep microorganisms from gaining a foothold. Any lubricant that gets pulled away by the flow of liquids such as blood is immediately replaced by more, migrating out from within the polymer.

The specific liquid-infused polymer that has been created for the study consists of solid silicone tubing, infused with silicone oil – both substances are non-toxic.

In lab tests, sections of both it and regular untreated silicone tubing were exposed to Pseudomonas aeruginosa, Escherichia coli and Staphylococcus epidermidis bacteria. All of these varieties are frequently responsible for urinary, tissue, and blood infections. The conclusion of the experiments was that the oil-infused silicone "greatly reduced bacterial adhesion and largely eliminated biofilm formation."

Although the tubing would presumably use up its oil reservoir at some point, the lubricating effect is still relatively long-lasting, and able to withstand sterilization. The technology could even have applications outside the field of medicine, such as preventing barnacles from attaching themselves to ships' hulls, and keeping things flowing in wastewater management systems and oil pipes.

Aizenberg and her team, incidentally, were also behind another very slippery material known (appropriately) as SLIPS. An acronym for Slippery Liquid Porous Surfaces, it was bio-inspired by the structure of the pitcher plant.

A paper on the liquid-infused polymer research was recently published in the journal ACS Biomaterials.

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