Click chemistry facilitates direct labelling and super-resolution imaging of nucleic acids and proteins

Various uorescence microscopy techniques which can bypass the spatial resolution limit have been developed in recent years. Commonly summarized as “super-resolution microscopy” techniques, they constitute a new and valuable toolbox for cell biology (for details on the different techniques, we refer to some recent reviews). All uorescence microscopy-based methods require suitable and specic strategies for labelling a target structure. An additional request for super-resolution microscopy is a particularly high labelling density, which is reasoned by the sampling theorem. An elegant strategy to covalently bind small synthetic uorophores to cellular target structures with high efficiency and specicity makes use of copper(I)-catalysed Huisgen 1,3-dipolar cycloadditions, which is one example of a chemical reaction today referred to as “click chemistry”. This technique was initially introduced to uorescence microscopy for labelling nucleic acids and phospholipids. In the recent years, the eld has evolved dramatically, and new developments include alternative chemical strategies for click-like reactions, copperfree click chemistry, live cell labelling as well as dual-colour labelling with two orthogonal click reactions. Click chemistry has also entered the eld of super-resolution microscopy,