Carbon-nanotube-based stimuli-responsive controlled-release system.

A stimuli-responsive controlled-release delivery system based on carbon nanotubes is demonstrated. Through TEM, FTIR spectroscopic, and thermogravimetric analysis, functional groups have been successfully attached to the open ends of the tubes, thereby enabling functionalized silica spheres to preferentially attach to the ends. This, in essence, plugs the ends of the tube. Controlling release of encapsulated materials within the tubes is illustrated by fluorescein-filled carbon nanotubes. The discharge process can be triggered by exposure to 1,4-dithiothreitol (DTT) or at elevated temperature. Moreover, both triggering systems, DTT and temperature, provide rate of release control through increased DTT concentration or temperature choice, respectively. This delivery system paves the way for the development of a new generation of site-selective, controlled-release, drug-delivery systems, and interactive nanosensor devices.