In Illinois, Northwestern University researchers are building structures using one atom at a time. They have created the world’s lowest density metal organic framework from two simple building blocks – uranium atoms and organic linkers. The 3D net of large and roomy pores are so large that scientists were able to place a large enzyme inside a pore meaning the new material can be used as protective housing for enzymes. While uranium is a very heavy metal, the atoms are so far away from each other in the structure that it makes their new material the lowest density ever made. But don’t worry about the new material being radioactive like a nuclear power plant kind of uranium – they used uranium 238, a nonradioactive isotope.