Johns Hopkins researchers have devised a way to use a brief burst of electricity to release biomolecules and nanoparticles from a tiny gold launch pad. The technique could someday be used to dispense small amounts of medicine on command from a chip implanted in the body. The method also may be useful in chemical reactions that require the controlled release of extremely small quantities of a material.

The technique was described Sept. 10 in a presentation by Peter C. Searson, a Johns Hopkins professor of materials science and engineering, during the 232nd national meeting of the American Chemical Society in San Francisco. "You can think of the useful biomolecule or nanoparticle as a balloon tethered to a surface," he said. "We use an electrical pulse to cut the tether, and it floats away."

This method could be used to control the release of drug molecules; nanoparticles; biopolymers such as peptides, proteins and DNA; and protein assemblies such as viruses, said Searson, who also is director of the Institute for NanoBioTechnology at Johns Hopkins.

"The technique is relatively simple, but nothing like this has been done before," he said. "Scientists have known that molecules could be removed from a surface in this way, but it's never been considered useful. They've been more interested in preventing this from happening."

Yet Searson and Johns Hopkins biomedical engineering graduate students Prashant Mali and Nirveek Bhattacharjee concluded that this controlled release of molecules might have important applications in the growing field of nanobiotechnology.

For their experiments, the researchers used gold electrodes, each as thin as a single strand of human hair, fabricated through the same photolithography techniques used to make computer chips. "We used a gold electrode because gold is a good conductor of electricity," said Mali, "and because it's an inert metal, it wouldn't get involved in any of the chemical r
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Contact: Phil Sneiderman
prs@jhu.edu
443-287-9960
Johns Hopkins University
11-Sep-2006