Fluorescent Photoswitchable Diarylethenes for Biolabeling and Single-Molecule Localization Microscopies with Optical Superresolution

TLDR

The authors synthesized reversible photoswitchable diarylethenes with a fluorescent closed form, functionalized with methoxy groups on the phenyl rings and varying numbers of carboxylic acid groups to achieve aqueous solubility. The resulting antibody‑conjugated diarylethenes show low aggregation, efficient photoswitching in aqueous buffers, specific staining of cellular structures, high emission efficiencies, low cycloreversion quantum yields, and enable superresolution imaging of tubulin, vimentin, and nuclear pore complexes using only 488 nm light without additional UV activation.

Abstract

A modular assembly of water-soluble diarylethenes (DAEs), applicable as biomarkers for optical nanoscopy, is reported. Reversibly photoswitchable 1,2-bis(2-alkyl-6-phenyl-1-benzothiophene-1,1-dioxide-3-yl)perfluorocyclopentenes possessing a fluorescent "closed" form were decorated with one or two methoxy group(s) attached to the para-position(s) of phenyl ring(s) and two, four, or eight carboxylic acid groups. Antibody conjugates of these DAEs feature low aggregation, efficient photoswitching in aqueous buffers, specific staining of cellular structures, and photophysical properties (high emission efficiencies and low cycloreversion quantum yields) enabling their application in superresolution microscopy. Images of tubulin, vimentin, and nuclear pore complexes are presented. The superresolution images can also be acquired by using solely 488 nm light without additional photoactivation with UV light. These DAEs exhibit reversible photoswitching without requiring any additives to the imaging media and open new paths toward the modular design of fluorescent dyes for bioimaging with optical superresolution.