Artificial, bone-like material for implantable medical devices

Scientists have developed an artificial skeleton-like material from silicon that may allow for improved integration of medical implants into the body.
The researchers, led by Bozhi Tian, assistant professor in chemistry at the University of Chicago, developed the first skeleton-like silicon spicules ever prepared via chemical processes.
"Using bone formation as a guide, the Tian group has developed a synthetic material from silicon that shows potential for improving interaction between soft tissue and hard materials," said Joe Akkara, a programme director in the US National Science Foundation materials research division, which funded the research.
"The group has created a material that preliminarily seems to enhance soft tissue function," Akkara said.

The team achieved many advances in the development of semiconductor and biological materials. One advance was the demonstration, by strictly chemical means, of three-dimensional lithography.
Existing lithographic techniques create features over flat surfaces. The laboratory system mimics the natural reaction-diffusion process that leads to symmetry-breaking forms in nature: the grooved and notched form of a bee stinger, for example.

The team developed a pressure modulation synthesis, to promote the growth of silicon nanowires and to induce gold-based patterns in the silicon. Gold acts as silicon's growth catalyst.
By repeatedly increasing and decreasing the pressure on their samples, the researchers were able to control the gold's precipitation and diffusion along the silicon's faceted surfaces.

"The idea of utilising deposition-diffusion cycles can be applied to synthesising more complex 3-D semiconductors," said co-lead author Yuanwen Jiang, a Seymour Goodman Fellow in chemistry at UChicago.
The synthetic silicon spicules displayed stronger interactions with collagen fibres - a skin-like stand-in for biological tissue - than did currently available silicon structures.
"One of the major hurdles in the area of bioelectronics or implants is that the interface between the electronic device and the tissue or organ is not robust," Tian said.
"The spicules show promise for clearing this hurdle. They penetrated easily into the collagen, then became deeply rooted, much like a bee stinger in human skin," Tian said.

The study was published in the journal Science.