In our efforts to understand the processes of life at cellular levels, we need to be able to observe how various materials move around inside living cells. A group of researchers have employed quantum dots – highly reflective nanoscale crystals – to make this possible, bonding them to a protein that regulates nerve tissue growth in rats. The dots are much brighter than the proteins, and so their movement can easily be tracked by microscope as they migrate around the interior of cells. This technique might be useful in the future for watching new drugs and medicines as they move inside the body.