Get enough bacteria in one place and they like to settle down into longer-term colonies, building sticky biofilms that protect them from our best cleaning efforts. But now, researchers from the University of Illinois have designed a technique that uses microbubbles as a scrubber to blast biofilms away.
Antibiotics are reasonably effective against free-roaming bacteria, but a biofilm forms a protective barrier that's hard for drugs and bug-killing chemicals to break through. These strong, sticky substances can cling to everything from your bathroom tiles to medical equipment and even your teeth.
"Most of us get those black or yellow spots in our showers at home," says Hyunjoon Kong, co-author of the study. "Those spots are biofilms and most of us know it takes a lot of energy to scrub them away. Imagine trying to do this inside the confined space of the tubing of a medical device or implant. It would be very difficult."
In this ongoing war, scientists have developed coatings that are too slippery for the bugs to get a grip on, heated up biofilms to breaking point using iron oxide nanoparticles, disrupted the communication networks bacteria use to establish a biofilm in the first place, and discovered new compounds that can kill superbug biofilms.
For the new study, the researchers developed a system that can bust through the biofilm barrier before targeting the bacteria that live inside. The key ingredient comes from another kind of microorganism – diatoms, which are species of algae with tough outer skeletons. Diatoms come in all kinds of shapes, but in this case the researchers chose a species shaped like hollow rods.
These diatoms are coated in nanosheets of manganese oxide, then when they're ready to fight the bugs, you just add hydrogen peroxide and set them loose on the surface of the biofilm. The hydrogen peroxide and manganese oxide react with each other inside the tube of the diatom, which creates a burst of microbubbles that jet out one end of the rod, pushing the diatom forward. This is apparently forceful enough to smash down the biofilm barrier.
"Once the diatoms break through to the internal structure of the biofilm, they continue to expel bubbles and facilitate the entry of hydrogen peroxide, which is an effective disinfectant against bacteria and fungus," explains Kong.
The team is encouraged by how effective the system is at clearing out biofilms, which they chalk up to it being a "mechanical" solution rather than killing the microbes chemically.
"We have arrived at a mechanistic solution for this problem and the possibilities for this technology are endless," says Simon Rogers, co-author of the study. "We are discussing our research with clinicians who have many exciting ideas of how to use this system that we did not even think of originally, such as the removal of dental plaque."
The research was published in the journal Applied Materials and Interfaces, and the technique can be seen in action in the video below.
Source: University of Illinois