Facile Blinking Dyes with Spontaneous Enol-Keto Tautomerism for Super-Resolution Imaging of Subcellular Targets

Fluorophores with controlled on–off switching properties and subcellular targeting abilities are essential for modern super-resolution microscopy techniques.However,the effective design strategies of blinking fluorophores are still limited with scarce building blocks(e.g.,rhodamine and cyanine analogues),and sophisticated functionalization is always required for organelle recognition.Therefore,exploring live-cell compatible and organelle-targetable fluorophores with a new blinking mechanism is of broad interest to promote the emerging development of superresolution microscopy.Here,we report a type of live-cell permeable fluorophore with a facile synthesis strategy to facilitate the imaging of lipid droplets and lysosomes using single-molecule localization microscopy.The fluorophores only require a two-step synthetic route.They show signature enol-keto tautomerism by spontaneous proton transfer at the ground state without additional photoactivation,which ensures blinking performance by exciting the minor portion of molecules in keto form.This fluorescence switching mechanism provides a distinct character from that of previously reported live-cell permeable dyes for super-resolution imaging,while the specific organelle binding affinity can be tuned by simply changing the targeting moiety of fluorophores.