Fluorescence nanoscopy by ground-state depletion and single-molecule return

Abstract

A simple yet powerful super-resolution imaging approach based on switching off ordinary fluorophores and localizing those remaining or regaining fluorescence is illustrated using continuous widefield illumination and imaging of fixed and living cells labeled with rhodamine-derived dyes or fluorescent proteins. Biteen et al., also in this issue, describe related work using the ordinary fluorophore of EYFP for super-resolution imaging. We introduce far-field fluorescence nanoscopy with ordinary fluorophores based on switching the majority of them to a metastable dark state, such as the triplet, and calculating the position of those left or those that spontaneously returned to the ground state. Continuous widefield illumination by a single laser and a continuously operating camera yielded dual-color images of rhodamine- and fluorescent protein–labeled (living) samples, proving a simple yet powerful super-resolution approach.