When someone has cancer, doctors often treat them with a number of different drugs that help to kill the cancer cells. The problem is, sometimes healthy cells get harmed by the very powerful drugs that doctors only want to work on the bad cells. Now scientists have found a way to use very tiny nanoparticles to help solve the problem of the drugs hurting the good cells. They take a small particle that looks almost like a very tiny tree, and attach the anti-cancer drug to some of the tree’s branches. They also attach another chemical called folic acid to some of the other branches. Cancer cells are very, very hungry for folic acid, so they gobble up the nanoparticles with the folic acid attached faster than normal, healthy cells do. This means the powerful anti-cancer drugs can act on mostly the bad cancer cells without harming the good, non-cancer cells.This makes those tiny nanoparticles very useful trees, indeed!