Topics: Biology, Diffusion, Quantum Dots, Quantum Mechanics
Quantum dots diffuse within living cells in a nearly two-dimensional fashion. This result, which was obtained using a new 3D microscopy technique that can track single particles, sheds fresh light on intracellular diffusion – a process that is critical for moving molecules around the cell and for mediating other important activities. According to study leader Hui Li, a biophysicist at the Chinese Academy of Sciences in Beijing and Beijing Normal University, the 2D motion he and his colleagues observed is robust and stems from the complex architectures of the flat “adherent” biological cells they studied.
Quantum dots make ideal probes for studying intracellular diffusion in living cells. They are similar in size to intracellular macromolecules and can be made to mimic biological materials relatively easily, by coating their surfaces with organic molecules. Previous studies, however, relied mainly on two-dimensional measurements of their movement, with the assumption that three-dimensional diffusion is an extension of 2D diffusion and is isotropic.
Quantum dots track two-dimensional diffusion in cells, Isabelle Dumé, Physics World
Physics and Nano 
