An exquisite container
By Diana Lutz

Nov. 3, 2009 -- In campy old movies, Lucretia Borgia swans around emptying powder from her ring into wine glasses carelessly left unattended. The poison ring is usually a confection of gold filigree holding a cabochon or faceted gemstone that can be broken to empty the ring's contents. It is invariably enormous — so large it is rather odd nobody seems to notice it.

Lucretia would have given her eyeteeth for the "smart capsule" devised in Younan Xia's laboratory at Washington University in St. Louis. A tiny cage of gold covered with a smart polymer, it responds to light, opening to empty its contents, and resealing when the light is turned off.

No Lucretia, Xia is a healer rather than a poisoner. The smart nanocage is designed to be filled with a medicinal substance, such as a chemotherapy drug or bactericide. Releasing carefully titrated amounts of a drug only near the tissue that is the drug's intended target, this delivery system will maximize the drug's beneficial effects while minimizing its side effects.  more...