Iterative expansion microscopy

Chang, J.-B., Chen, F., Yoon, Y.-G., Jung, E. E., Babcock H., Kang J.-S., Asano S., Suk H.-J., Pak N., Tillberg P.W., Wassie A., Cai D., Boyden E.S. (2017) Iterative expansion microscopy, Nature Methods 14:593-599.

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We recently developed a method called expansion microscopy, in which preserved biological specimens are physically magnified by embedding them in a densely crosslinked polyelectrolyte gel, anchoring key labels or biomolecules to the gel, mechanically homogenizing the specimen, and then swelling the gel–specimen composite by ~4.5× in linear dimension. Here we describe iterative expansion microscopy (iExM), in which a sample is expanded ~20×. After preliminary expansion a second swellable polymer mesh is formed in the space newly opened up by the first expansion, and the sample is expanded again. iExM expands biological specimens ~4.5 × 4.5, or ~20×, and enables ~25-nm-resolution imaging of cells and tissues on conventional microscopes. We used iExM to visualize synaptic proteins, as well as the detailed architecture of dendritic spines, in mouse brain circuitry.


Tools for mapping the molecules and structure of the brain

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