A non-toxic, user-friendly buffer that enhances green fluorophore performance in conventional and super-resolution imaging

Fluorophore brightness and photostability continue to be limiting factors in fluorescence microscopy. Several buffers that enhance these properties have been identified to date, though they do not work for all dyes, may require harmful components, or have limited storage lives. We have identified a simple, in-expensive, and non-toxic buffer that strongly enhances the brightness and resistance to photodestruction of green emissing synthetic fluorophores, using potassium iodide as a main photostabilizing additive and MgCl ₂ as enhancer for binding kinetics in DNA-PAINT super resolution imaging. We show that this ‘AN-ice’ buffer can deliver an up to 30% improvement in fluorescence brightness and 5x more detected events in DNA-PAINT imaging. Furthermore, the same effect can be used to strongly increase the photobleaching resistance of all the green dyes tested for conventional imaging.