Credit: AM.CHEM.SOC.

J. Am. Chem. Soc. doi:10.1021/ja9061085 (2009)

Silica nanoparticles can act as tiny containers to deliver drugs in response to enzymes, thanks to Chulhee Kim and his colleagues at Inha University in Incheon, South Korea.

The particles are pitted with pores that are capped with cyclodextrin molecules. The pores bear the cargo molecules — in the authors' experiments, fluorescent calcein dye.

The enzyme α-amylase, which increases in acute pancreatitis, was added to a buffer solution containing the particles. The enzyme degraded the cyclodextrin and calcein flooded out (schematic pictured). The lipase enzyme had a similar effect, but when no enzyme was present, the pores remained closed and their contents locked away.

The system could have uses in drug delivery, diagnostics and imaging, the authors say.