Thursday, June 8, 2006 | Nanoparticles

Programming Nanoparticle Release
Imagine an implantable device that could be programmed to release exact numbers of drug-laden nanoparticles at specific times over the course of weeks or months or even in response to incoming biochemical signals. Research by Peter Searson, Ph.D., and his colleagues at Johns Hopkins University shows that it may be possible to construct such a device using self-assembled monolayers of nanoparticles deposited on gold electrodes.

Writing in the journal Nano Letters, the Johns Hopkins team describes how it used sulfur-containing linker molecules to attach nanoparticles to gold electrodes. Sulfur and gold form a very strong chemical bond, but one that is reversible when electricity flows into the gold. Therefore, applying a current to the gold electrode triggers the immediate release of the sulfur-containing linker and the nanoparticle. The researchers also found that any nanoparticles that happen to stick directly to the electrodes during the initial tethering reaction remain attached to the electrodes and therefore would not confound the programmed release of specific numbers of nanoparticles.

The researchers note that standard microfabrication techniques can produce gold electrode arrays capable of releasing femtomole quantities of nanoparticles, suggesting that such a device could be programmed to achieve exquisite control over the amount of drug delivered in the body. The low power requirements of this device also bode well for its further development as a biocompatible drug delivery system.

This work is detailed in a paper titled, “Electrochemically programmed release of biomolecules and nanoparticles.”