Body Electric

Opposites, many lovers say, can and do attract-it's just a matter of the right chemistry. A team of University chemists believes this maxim can be true at the cellular level too, and its research is bringing together the most extreme of opposites-living cells and man-made materials-in an effort to create tiny biomedical devices smart enough to communicate with the body's building blocks.

"The technologies underlying microelectronics and biotechnology are completely different," says Milan Mrksich, associate professor in chemistry, who presented his team's work on surface chemistry in September at the BioMEMS and Biomedical Nanotechnology World conference. "That means it's difficult to combine these two technologies into some common application or technology."

Mrksich and his group have two goals: not only are they figuring out how to join cells with manufactured materials, they're also teaching the two to talk to each other, by converting electrical signals into biological ones and vice versa, translating the activity of specific cells into a language that a microprocessor can understand. The "surface" aspect of the research is important because that's where two critical functions occur: cell adhesion (getting cells and manufactured materials to stick together) and cell migration (how cells move). Mrksich's team is designing electrically active surfaces that enable the scientists to control both functions in an experimentally clean, systematic way.

Potential applications include biomedical instruments for pharmaceutical research and medical diagnostics; inexpensive, portable devices that can monitor anything from blood chemistries to bacteria in ground beef; new prosthetics; and sophisticated sensors able to detect infection from biological warfare. Mrksich is especially intrigued by the potential for new drugs to affect cell migration. "In cancer, cell migration is a key element that leads to the spread of a tumor," he says. "A lot of anticancer drugs function by blocking migration of tumor cells. It's important for the pharmaceutical companies to have tests that evaluate molecules for their ability to block cell migration."

In addition to blocking movement, the researchers hope to learn other ways to control cell activity. For example, they are developing cell-based sensors and learning how to integrate cells with electronics so the cell itself serves as a sensor. The goal is to design a device that will electrically signal when a cell becomes infected with a hazardous agent like anthrax or smallpox. Such early-warning sensors could detect exposure days before victims show symptoms. "It's difficult to make man-made sensors that can detect those agents at low levels quickly and reliably," Mrksich explains. "At the same time, cells are good at detecting these agents because they are the natural victims of those agents."

Pharmaceutical companies already use cells as sensors in drug development. "By building devices that can more rapidly and accurately tell us how the cells respond to potential drugs," says Mrksich, "we can know if the drugs are toxic before we go to clinical trials, and we can better understand what side effects they might have before we test them in people."

The work also could be useful in the development of prosthetic devices for people who have lost muscular control because of nerve or spinal cord damage. It would be possible, in theory, to engineer an implantable device that re-establishes connections with neurons, allowing the brain to again link to and control a muscle. The challenge, Mrksich says, is to learn how to connect an electronics component with neurons so the component recognizes when a neuron fires, then relays that signal, causing another neuron or a muscle to fire. - S.A.S.