Long before gold nanorods, carbon nanotubes, and magnetic nanoparticles were first made in the lab, nanoscale structures made from biological materials were being, and continue to be, constructed in living organisms. Life wouldn’t exist without nanostructures. Proteins that help build our muscles, antibodies that fend off disease and infection, membranes that keep unwanted materials out of our cells, even the fundamental building block of life … DNA, all exist at the nanoscale. What makes nanotechnology for medical applications such a compelling field is the fact that biology already operates at the nanoscale. Why make a diagnostic tool or medical device the size of a cell phone when you can make one the size of a cell membrane?