Aptamer-Based Cell Nucleus Imaging via Expansion Microscopy

Expansion microscopy (ExM) is a newly developed technology inrecent years that enables nanoscale imaging under conventional microscopes. Herein,we report an aptamer-based ExM imaging strategy. A nucleus-targeting aptamer Ch4-1 was chemically labeled with a dye and an acrydite at each end to perform thefunctions of molecular recognition,fluorescence reporting, and gel anchoring. Afterbinding cell nucleus, the dual labeled aptamer Ac-Ch4-1-FAM directly participated ingelation and anchored in polyacrylamide gel. After expanding the gel, high-resolutionimaging was achieved by confocal microscopy. Multicolor ExM imaging was alsorealized by combining Ac-Ch4-1-FAM, antibodies andfluorescent dyes. This aptamer-based ExM could clearly image the chromatinmorphology at different mitotic stages. The expansion process is simple and the aptamer labeling is easy. The aptamer-based ExMholds great promise in super-resolution imaging of cells and tissues.