It’s never a good thing, when a bacterial biofilm forms on the surface of a medical implant. There could soon be a new way of eradicating such films, however, using tiny remote-control liquid-bodied robots.
When pretty much any manmade object is implanted in the body, there’s a chance that harmful bacteria will colonize its surface – and the surrounding tissue. The microbes go on to form a viscous coating known as a biofilm, which is resistant to antibiotics. For this reason, a second surgery is sometimes required to clean off and disinfect the implant.
In the past, scientists have developed tiny remote-control objects – “robots,” technically speaking – that could be used to remove biofilms. Unfortunately, however, these bots have typically only been effective on fairly smooth, uniform surfaces. They simply can’t reach into nooks and crannies.
The new liquid-bodied robots were designed with that limiting factor in mind. They are the result of a study led by scientists from the Chinese University of Hong Kong (CUHK) working with colleagues from Nanyang Technological University in Singapore, and the Max Planck Institute for Intelligent Systems in Germany.
Each robot is basically a small blob of cross-linked polyvinyl alcohol (PVA) hydrogel, which is loaded up with neodymium-iron-boron magnetic particles along with two antibacterial agents: levofloxacin and indolicidin.
The idea is that in the event of an infection at an implant site, the robot gets delivered to that site via a minimally-invasive endoscopic procedure. Once the bot has been deposited on the biofilm, its location is tracked in real time via both the endoscope and x-ray fluoroscopy.
CUHK
Utilizing a permanent magnet mounted on a robotic arm located outside the patient’s body, it’s possible to remotely propel and steer the robot. Depending on how the magnet is moved by the arm, the bot can either slide its way across smooth substrates or roll across more irregular surfaces such as medical meshes, oozing into them as it does so.
In either case, the robot destroys the biofilms in three ways.
First of all, it simply plows much of them away as it pushes its way through the material. Additionally, it releases its two antibacterial agents, killing the microbes that produce the biofilms. Finally, any biofilm debris that withstood the initial onslaught sticks to the robot’s gelatinous body, getting carried away with it instead of remaining on the implant.
CUHK
Once the biofilm-eradication process is complete, the robot gets removed from the body via a laparoscopically-inserted magnet.
In lab tests performed on an extracted pig digestive system, the technology was able to reduce the biofilm on a 3D-structured hernia mesh by 84%, plus it killed 87% of the bacteria on a metal binary stent. And the testing didn’t stop there.
“In a mouse model with infected stents, complete weight recovery [of the mice] was observed within 12 days, with a 40% reduction in inflammation indicators compared to the control group,” says CUHK’s Prof. Zhang Li, who led the study.
A paper on the research was recently published in the journal Science Advances.
Source: CUHK