Mostafa El-Sayed’s chemistry career spans almost 60 years. His research includes using lasers and other tools to better understand the properties and behavior of molecules, especially the properties of nanoscale materials. He is a pioneer in the use of nanomedicine to fight cancer. He even has a spectroscopy rule named after him: the “El-Sayed rule,” which deals with how energy cascades into other forms when electrons are absorbed. For all of these reasons and more, the American Chemical Society awarded it’s highest honor, the Priestley Medal, to El-Sayed in 2016.