A technique using a brief burst of electricity to release biomolecules and nanoparticles from a tiny gold launch pad someday could be used to dispense small amounts of medicine on command from a chip implanted in the body, according to a presentation at the 232nd national meeting of the American Chemical Society in San Francisco on Sept. 10.
"The technique is relatively simple, but nothing like this has been done before," said Peter C. Searson, PhD, professor of materials science and engineering, Johns Hopkins University, Baltimore. "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."
However, Dr. Searson and Johns Hopkins University biomedical engineering graduate students Prashant Mali and Nirveek Bhattacharjee concluded that a controlled release of useful molecules might have important applications in the growing field of nanobiotechnology.
They used gold electrodes, each as thin as a single strand of human hair, that were fabricated through the same photolithography techniques used to make computer chips. They tethered each useful biomolecule to this surface using a long chain of hydrocarbon molecules. At one end, the chain was anchored to the electrode by a gold-sulfur bond. At the other end of the chain was the biomolecule researchers wanted to release on command. When researchers sent a brief, mild pulse of electricity through wires attached to each electrode, the current caused the bond between the sulfur atoms and the gold platform to break, setting the tethered molecule free.
The researchers said that in theory this technique could be incorporated into a biocompatible implant chip that would release medicine inside a patient on command.
Scientists elsewhere are working on other drug delivery techniques, such as microfabricated containers that unload their medication inside the body when a lid dissolves. Although their approach requires further research and development, Dr. Searson and his team said it could have several advantages over the container technology.
"Because our molecules are attached to a surface, we can work with much smaller concentrations," Dr. Searson said. "We’ve also shown that our system is reusable. After a group of molecules is released, you can easily attach new molecules to an electrode and use it again."
Researchers also reported their technique in the June issue of the journal Nano Letters.
