Protein-Retention Expansion Microscopy (ExM): Scalable and Convenient Super-Resolution Microscopy.

Expansion microscopy (ExM) is a method to expand biological specimens ~fourfold in each dimension by embedding in a hyper-swellable gel material. The expansion is uniform across observable length scales, enabling imaging of structures previously too small to resolve. ExM is compatible with any microscope and does not require expensive materials or specialized software, offering effectively sub-diffraction-limited imaging capabilities to labs that are not equipped to use traditional super-resolution imaging methods. Expanded specimens are ~99% water, resulting in strongly reduced optical scattering and enabling imaging of sub-diffraction-limited structures throughout specimens up to several hundred microns in (pre-expansion) thickness.