Infections on implants
Joint replacements, pacemakers and catheters are prone to biofilms, bacterial sheets that can cause hard-to-treat, antibiotic-resistant infections. A University of Michigan Engineering team built an implantable platform, DARTS (dynamically actuated reconfigurable topographical surface), that reduced bacterial burden and improved tissue response in mice, according to the university’s October 27 news release. The study appeared in Advanced Functional Materials.
Two mechanisms
The surface is built from layered coatings on a pre-stretched plastic film that is heated at 130 C so it shrinks and wrinkles. A single coating gives nano-wrinkles with wavelengths below 400 nanometers that puncture both gram-negative and gram-positive bacteria. Micro-wrinkles around 2 microns failed, because bacteria settled in the grooves.
A soft actuator, a tiny metallic spring in a silicone block, adds active cleaning. Current heats and contracts the spring, squeezing the surface and popping bacteria off.
Results
With bacteria, actuation plus nano-wrinkles nearly disrupted and removed mature biofilms, and the device held its shape through 200 cycles. In mice with Staphylococcus aureus under the skin, the device was actuated 20 times after surgery and on days one, three and five; after seven days, bacterial contamination was markedly lower with better tissue outcomes than controls. A near-infrared laser also actuated it wirelessly.
Next steps
The researchers describe a move toward clinical use but this is animal-stage work. Safety, durability over longer periods and performance on real implant designs still need study.
Practical takeaways
- Preclinical research only.
- Wireless actuation could make the approach practical for implants.
- Watch for tests on real implant materials and in larger animals.
Bottom line
Combining passive nano-texture with active motion is an inventive attack on implant infections. Translation to patients is still ahead.