New nanovalve to deliver targeted drugs.

• Position: Nanotechnology - Brief article

We encounter valves every day, whether in a water faucet, automobile carburetor, or bicycle tire tube. Valves also are present in the world of nanotechnology. A team of researchers headed by J. Fraser Stoddart and Jeffrey I. Zink at the University of California, Los Angeles, has developed a new nanovalve. In contrast to prior versions, which only function in organic solvents, this valve operates in an aqueous environment and under physiological conditions--prerequisites for any application as a gate for nanoscopic drug-transport agents, which need to set their cargo free at the right place and time.

In order for pharmaceuticals to affect only the target diseased organ, suitable nanopackaging is required to bring the drug to the target area and release it there solely. One example of a good nanoscopic packaging agent is a tiny sphere of porous silica. Its pores can be filled with the drug and closed with tiny controllable valves.

The scientists attached stem-shaped molecules onto the surface of the porous spheres and filled the pores with guest molecules. At...