Boundary Effects

The scalpel is a wondrously simple and effective tool that has saved many lives. But from the vantage point of a human cell, a scalpel is about as precise as an incoming asteroid. The processes that constitute life and death, health and disease, occur within cells on the scale of billionths of a meter (nanometers). This is roughly the dimension of the DNA double helix, the proteins issuing from the genetic code, and all the other macromolecules that float in the aqueous environment of the living cell. The ultimate medical toolkit is not the scalpel and suturing needle; it is a set of tools small enough to go right inside the cell and repair individual DNA molecules or proteins the way a mechanic adjusts the timing belt on a Honda Civic.

Enter nanomedicine. As described in this issue’s Special Report, nanomedicine is the application of techniques from materials science to the world of biomedicine. It could provide just the molecular toolkit the doctor ordered. One tool in the box would be “quantum dots,” described in Senior Editor David Rotman’s story as molecule-sized aggregates of semiconductor atoms that attach themselves to specific biological structures and light up with a message: “I’m stuck right here on this cancer protein,” for instance. Like a flare dropped from an airplane, this signal would trigger a volley of artillery fire in the form of chemotherapeutic agents.

One of the interesting things about the development of quantum dots is that researchers who worked on them originally had no inkling of medical applications. In the 1980s, quantum dots didn’t seem to have any applications at all. They were curiosities, remarkable to materials scientists largely because semiconductors usually exist as crystalline solids, not molecule-sized aggregates.

The “aha” moment that turned lab curios into hot technology was the realization that they are on just the right scale to interact with living cells. Paul Alivisatos, a Berkeley chemist, says the light bulb went on for him when he saw that “quantum dots are macromolecules, the size of proteins. Once you realize that the size scales are compatible, you say, ‘Okay these things can go together.’” It wasn’t long before quantum dots were being looked at as tools for diagnosis and other clinical chores. As freelancer David Voss describes in our Special Report, they’re being joined in the nano-toolkit by other compounds and devices that can operate inside the cell.

One sign that nanomedicine is hot is that, as Voss notes, a number of major research universities have established centers to study it. We predict that within five years it will be commercially significant and within 10 it will begin to have a major impact on medicine. That’s a bold prediction, and it may turn out to be wrong, but one thing that will not turn out to be wrong is the importance for today’s technology of the process of convergence. What’s most striking about the story of nanomedicine is that research that began way over there, in physics labs, is suddenly all the way over here-in biomedicine. The convergence of nanotechnology and medicine is just one example of the exciting research taking place where established disciplines touch. Part of the mission of Technology Review is to cover those “boundary effects.” Whether it’s nanotech and medicine or computer science infiltrating the Human Genome Project, we will be there. And, as long as you read us, so will you.