These nanocompartments - imagine a kind of tiny apartment house - form when single cells are added to a visually clear, aqueous solution of silica and phospholipids, and the slurry is then dried on a surface. (Phospholipids are two-sided molecules that make up cell membranes.)
Ordinarily, the drying of lipid-silica solutions produces an ordered porous nanostructure by a process known as molecular self-assembly. This can be visualized as a kind of tract housing.
In the current experiments, however, the construction process is altered by the live yeast or bacteria.
During drying, the cells actively organize lipids into a sort of multi-layered cell membrane that not only serves as an interface between the cell and the surrounding silica nanostructure, but acts as a template helping to direct the formation of the surrounding silica nanostructure.
This improved architecture seamlessly retains water, needed by the cell to stay alive. Further, by eliminating stresses ordinarily caused by drying, the nanostructure forms without fine-line cracks. These improvements help maintain the functionality of the cell and the accessibility of its surface.
By comparison, the more common practice of merely 'trapping cells in gels' leads to stress, cracks, and rapid cell death upon drying.
Already launched on the space shuttle
The incorporated cells of the Brinker group are self-sustaining - they do not need external buffers and even survive being placed in a vacuum.
To study their use as cell-based sensors for extreme environments, samples of the yeast- and bacteria-containing nanostructures were launched on the recently completed mission of the US space shuttle Discovery. On the Space Station, experiments will be performed to determine their longevity when exposed to the extreme stresses of
Source:DOE/Sandia National Laboratories