It is currently challenging to directly observe the formation of intracellular nanostructures in the lab. In a new report, Miaomiao Zhang and a research team in chemistry, life sciences, medical engineering and science and technology, in China, used a rationally designed small molecule abbreviated NBC-Iod-CBT (short for 4-nitrobenzyl carbamate–Cys(SEt)-Asp-Asp-Phe(iodine)–2-cyano-benzothiazole) and directly observed intracellular nanoparticle formation with nanocomputed tomography (nano-CT).