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Sticking Spiny Silicon Nanowires To Soft Tissue

Materials: Silicon spicules bolster nanowire interfaces with biomaterials

by Matt Davenport
June 29, 2015 | A version of this story appeared in Volume 93, Issue 26

Credit: Tian Group/UChicago
Each “vertebra” is about 200 nm in length in this tomographic reconstruction of a wire.
Tomographic image of spiny silicon nanowire.
Credit: Tian Group/UChicago
Each “vertebra” is about 200 nm in length in this tomographic reconstruction of a wire.

Silicon is perhaps the most biocompatible semiconductor there is, says Bozhi Tian, a materials scientist at the University of Chicago. But he and his colleagues thought there was room for improvement when it came to interfacing nanosilicon with soft tissue. So researchers at the University of Chicago and Northwestern University devised a method to create spiny silicon nanowires to enhance a structure’s ability to cling to biomaterials (Science 2015, DOI: 10.1126/science.1257278). To do this, the team tweaked a conventional nanowire growth procedure in which silane gas decomposes and silicon atoms accumulate at catalytic gold nanoparticles. Once nanowires start sprouting from the catalyst particles, gold atoms begin diffusing along nanowire surfaces. The researchers realized they could control the gold’s diffusion rate by modulating the gas pressure during growth, effectively letting them pattern a metal mask on the silicon wires. Once the masked wires finished growing, the researchers could wet etch them to create anisotropic, three-dimensional structures that resemble vertebrae. These structures stuck well to collagen hydrogels, Tian says, and the team now plans to test the wires in devices designed to stimulate brain tissue.


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