Scientists at Brown University have developed a new kind of prosthesis that creates a closer seal between the implanted material and body contact area, thus decreasing the potential for bacterial colonization at the transcutaneous device.

The nanoscale surfaces mimic the contours of natural skin by attracting skin cells that over time build a natural seal against bacterial invasion. This development will help protect against the problem of bacteria entering the body through the space where the device has been implanted [Zile et al., J Biomed Mater Res Part A (2011) 97, 59].
One of the authors of the paper published in the Journal of Biomedical Materials Research A, Professor Thomas Webster at Brown University said “You need to close (the area) where the bacteria would enter the body, and that’s where the skin is”.
Webster and his team have successfully managed to modify the surface of titanium leg implants to hasten skin cell growth; the modification helps create a natural skin layer which seals the gap where the device is implanted into the body. The researchers also created a molecular chain that allows an implant surface to be covered with skin cell-growing proteins, which promotes skin growth.
The scientists encouraged skin growth in a two step process. In the first step the researchers excited titanium coatings at the point the implant was inserted into the bone. They created areas of ~20 nm mounds; imitating the contours of the skin and tricking skin cells to grow on the surface.
The second step involved growing the molecular chain, and saw the tip of the prosthesis dipped in to hydrofluoric acid whilst a charge was passed through it. This caused the titanium atoms on the surface of the prosthesis to reorder themselves forming hollow tubular structures which rose perpendicularly from the surface. Skin cells then very quickly colonized these hollow nanotubular surfaces.
In vitro tests have so far been very successful. “You definitely have a complete layer of skin, there’s no more gap for the bacteria to go through”, says Professor Webster.
The next step will be to look at in vivo testing.


Jonathan Agbenyega