In medicine, the brain acts as a kind of fortress. “It protects itself and doesn’t let much go by,” euphemizes Professor Sébastien Lecommandoux. Not much, including treatment to help him when something as serious as glioblastoma attacks him. One of the most aggressive brain tumors, this tumor affects about 3,500 people a year, more than 2,000 of them men. Then the researcher and his team set out to break through the barrier, break down the locks. Their lever: nanoparticles, this group of infinitely small molecules (they are 1000 times thinner than the diameter of a hair), capable of delivering treatments to the cells that need them. In other words, smart drugs.