Super resolution simultaneous imaging of proteins and mRNA via expansion microscopy

Abstract

Visualizing multiple biomolecular species with nanometer-scale precision can provide essential knowledge to understand the molecular mechanisms of biological phenomenon. In 2015, a new super-resolution microscopy technique, called expansion microscopy, was reported; in this technique, higher lateral and axial resolution are achieved by physically expanding specimens via a swellable hydrogel (ExM; Science 347(6221):534­548, Nat. Biotechnol. 34(9):987-992). Briefly, target specimens, such as cultured cells or tissue slices, are embedded in a swellable hydrogel. During the embedding process, proteins of interest are chemically anchored to the hydrogel. Then, the specimen-hydrogel composite is isotropically expanded in de-ionized water. During the expansion, closely-located proteins move apart, resulting in 60-nm resolution when imaged with diffraction-limited microscopy. Here, we show that multiple biomolecular species of the brain can be visualized with the same resolution via expansion microscopy. We believe that this work will provide richer molecular information of the brain.