Marek Romanowski, PhD, and his work on translating physics into medical products have huge implications for the evolution of personalized medicine. On cue, a tiny pillbox of gold floating in your bloodstream can deliver its medicine exactly to the right cell, one that is sick with cancer, avoiding all of your healthy cells. A gold capsule – about 50 to 200 nanometers in diameter, large enough to do the work of transporting a few molecules of medicine and respond to light signals – is too large to pass out through the kidneys. But on command by an enzyme, it can fall apart into pieces smaller than 10 nanometers, just a few molecules. The new size can easily leave our bodies at no risk. The gold pillbox has many other possible applications. In addition to delivering a drug, it can become a part of a diagnostic test, or deliver genetic material to a cell to permanently modify the cells’ DNA—a key step in gene therapy.