Having formed the sacs, Stupp and his team next studied human stem cells engulfed by the self-assembly process inside sacs that they placed in culture. The researchers found that the cells remained viable for up to four weeks, that a large protein -- a growth factor important in the signaling of stem cells -- could cross the membrane, and that the stem cells were able to differentiate.
We expect that genes, siRNAs and antibodies will cross the membranes as well, making this mini cell biology lab a powerful device for research or therapies, said Stupp. For the development of cancer therapies, we will be able to confine cells within the sacs and study their reaction to different types of therapies as well as to signaling by different cells in neighboring sacs.
In a clever demonstration of self-repair, if the sacs membrane had a hole (from a needle injection, for example), the researchers simply placed a drop of the PA solution on the tear, which interacted with the HA inside, resulting in self-assembly and a sealed hole.
The membrane is a fascinating and unusual structure with a high degree of hierarchical order, said Stupp. The membrane grows through a dynamic self-assembly process which generates hybrid nanofibers made up of both molecules and oriented perpendicular to the plane of the membrane. This architecture is very difficult to get spontaneously in materials. Using the right chemistry, the thick membrane structure could be designed to get conduits of charge in solar cells or nanoscale columns of catalytic nanostructures that would extend over arbitrary macroscopic dimensions.
While the underlying, highly ordered structure of the sacs and membranes has dimensions on the nanoscale, the sacs and membranes themselves can be
|Contact: Megan Fellman|