Chuck Bednar for redOrbit.com – Your Universe Online
Pacemakers and other artificial medical implants can often cause medical complications by triggering the body’s natural defenses, but researchers at ETH Zurich have found a way to make these implants more biocompatible by coating them with fabricated cellulose-sheaths.
“Braille” for the body
Experts had already learned that cells tend to cling better with rough or structured surfaces. However, it was previously possible to apply these surface structures to bacterial cellulose, a substance that has garnered a lot of attention in the scientific community recently due to its durability, adaptability and the fact that the human body tolerates it well.
Now, professors Dimos Poulikakos and Aldo Ferrari from the ETH Zurich Laboratory of Thermodynamics in Emerging Technologies and their colleagues have successfully created bacterial cellulose with a controlled surface structure. Their process uses a silicon mold with a 3D optimized geometry (such as a line grid) on a micrometer scale, which then floats on the surface of a nutrient solution in which the cellulose-producing bacteria grow.
The bacteria then create a dense network of cellulose strands at the interface between liquid and air, the study authors explained. When the mold was present, the bacteria tended to conform to it, producing a cellulose layer together with a negative replica of the line grid. The line grid also enabled the bacteria to produce additional cellulose strands in approximate alignment.
“In principle, human cells have the ability to identify fibers, such as endogenous collagen, as part of the connective tissue,” Ferrari explained. The cellulose strands and the grid pattern provided cells with an orientation along predetermined paths that can be sensed – something that he noted would be “of major benefit to wound dressings,” since skin cells could “grow over a wound more effectively if they moved in accordance with structured cellulose.”
We promise we’re going to get to the Braille reference
This material also seems to have some type of memory, as the structure is retained even when the cellulose is dried for storage purposes and moistened again just before use. Poulikakos explained that it is now possible to produce cellulose surfaces that contain with a message for the cells that will eventually grow there, noting that it is similar in nature to “a form of Braille.”
These structures will make it possible for a desired message, intended for layer use, to be encoded on the surface. These structures would not only serve as a method of orientation for cells, but would also help minimize the body’s adverse reaction to artificial medical implants.
In mouse studies, the ETH Zurich researchers compared smooth and structured cellulose, and found that the mice with structured cellulose inserted under their skin showed significantly fewer signs of inflammation. They are now planning to test the material under more complex condition as part of a follow-up study.
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