A Nontoxic, User-Friendly Buffer That Enhances Green Fluorophore Performance in Conventional and Super-resolution...

Fluorophore brightness and photostability continue to be limiting factors in (super-resolution) fluorescence microscopy. Several buffers that enhance these properties have been identified to date, but they often fail to work universally across different dyes, may contain hazardous components, or suffer from limited shelf life. In particular, green dyes typically perform worse than other colors and few additives that enhance their performance have been identified. We present a simple, cost-effective, and nontoxic buffer that markedly improves the performance of green-emitting synthetic fluorophores in DNA-PAINT imaging. Our "ANice" buffer combines potassium iodide as a photostabilizing additive and MgCl2 as an enhancer of binding kinetics. This new buffer increases the amount of detected molecules by a factor of 5 while delivering up to 30% improvement in fluorescence brightness. Furthermore, we show that the same effect can be used to strongly increase the photobleaching resistance of green dyes for conventional imaging.