Imagine that we could make cars, aircraft and submarines as small as bacteria or molecules. Microscopic robotic surgeons, injected in the body, could locate and neutralize the causes of disease—for example, the plaque inside arteries or the protein deposits that may cause Alzheimer’s disease. And nanomachines—robots having features and components at the nanometer scale—could penetrate the steel beams of bridges or the wings of airplanes, fixing invisible cracks before they propagate and cause catastrophic failures.
In recent years chemists have created an array of remarkable molecular-scale structures that could become parts of minute machines. James Tour and his co-workers at Rice University, for instance, have synthesized a molecular-scale car that features as wheels four buckyballs (carbon molecules shaped like soccer balls), 5,000 times as small as a human cell.