Woong Kim, Jennifer K. Ng, Miki E. Kunitake, Bruce R. Conklin,* and Peidong Yang*
J. Am. Chem. Soc. 2007, ASAP Published on 05/22/07.
A short report from Berkeley scientists showed that SiNWs vertically aligned on substrates - like a panel of needles - can penetrate through mammalian cells, such as mouse embryonic stem (mES) cells and human embryonic kidney (HEK 293T) cells.
The cells were directly cultured on the Si needle panel (CVD on Si-(111) substrates) and found to be able to survive for a certain period of time, depending upon the diameter of the SiNWs. The larger diameter ones (~400 nm) seemed to be more lethal upon penetration (cells died in a day), while the smaller ones (d~30 nm) were much more benign (5-day survival).
The substrate was demonstrated as a substitute (of gelatin-coated tissue culture grade plastic plates) for maintenance of differentiated stem cells. The embroyid bodies grow and beat on the needle panel for more than a month.
When the SiNW panel was coated with plasmid DNA (requiring PEI-coating first to introduce a counter-ion layer), very limited amount (less than one percent) of cells were found to express the gene introduced.
The work is quite preliminary in comparison to the much "maturer" carbon nanotube field, but is certainly a first wave to interface more varieties of inorganic wires with cells to take advantage of some specific characteristics of these NWs. It is anticipated water-soluble NWs would be available and used for much more diverse and in-depth studies.
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