Nowadays, zinc oxide nanoparticles are among the most commonly used nanomaterials. They seem to be safe for humans, but there are still no standards for their toxicity, and despite investigations, the toxicological impact of ZnO nanomaterials remains ambiguous. Researchers from the Polish Academy of Sciences (IPC PAS) in Warsaw and the Warsaw University of Technology (PW) have recently developed a method for producing defect-free ZnO quantum dots with enduring physicochemical properties such as monodispersity, a relatively high quantum efficiency, record-long luminescence lifetimes and EPR silence under standard conditions. The tightly coordinated and impermeable organic shells that stabilize the surface make the new ZnO quantum dots resistant to both chemical and biological environments.