Zrazhevskiy, P. & Gao, X. Nat. Commun. 4, 1619 (2013).

On top of being stable and bright, quantum dots also feature narrow emission spectra, leading advocates to champion their potential for multiplexed probing. In reality, however, multiplexed immunolabeling with quantum dots has been limited by technical issues. Zrazhevskiy and Gao introduce multicycle multicolor molecular profiling (dubbed M3P), showing that five staining cycles with five antibodies each can be applied to a single sample. They first create a library of quantum dots conjugated to protein A and then simply mix each with a different antibody at high concentration to produce quantum dot–linked antibodies. Each staining cycle is imaged with a hyperspectral camera and followed by destaining. The researchers demonstrate probing with minimal aggregation, probe cross-talk and sample degradation and provide preliminary evidence to suggest that the method could be used to image 100 targets.