Bistable rotaxanes are mechanically interlocked molecules that have found a number of uses in nanotechnology. Now comes a report that these nanotech switches might be pressed into service as valves so that nanoparticles only release drugs in desired target areas. From “Switchable nanovalves: pH-sensitive pseudorotaxane as reversible gate for drug nanotransporter“:
A team of researchers headed by J. Fraser Stoddart and Jeffrey I. Zink at the University of California, Los Angeles, has now developed a new nanovalve. In the journal Angewandte Chemie, the scientists reveal what is special about it: 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 only there. 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.