Expansion Microscopy for Brain Imaging
Understanding the organ-wide molecular architecture of proteins is required to dissect the mechanisms of various diseases and answer many scientific questions. Accordingly, there is a significant need for an imaging methodology that is capable of imaging proteins at nanoscale resolution over whole organs. In 2015, a technique called expansion microscopy (ExM) was developed. This technique increases the resolution of conventional microscopy several-fold by physically expanding a specimen with a swellable polymer network. After expansion, specimens become transparent, enabling super-resolution imaging of relatively thick tissue slices without ultra-thin sectioning. Recently, multiple ExM variants which demonstrated expansion microscopy with conventional fluorophore-conjugated antibodies, super-resolution imaging of RNA in cells and tissue slices via expansion, multiplexed protein imaging via post-expansion antibody staining, and sub-20-nm resolution via expanding specimens more than 20-fold have been developed. This chapter presents the detailed molecular principles of ExM and its variants to understand the differences between various ExM-related techniques.
This work was supported by Samsung Research Funding & Incubation Center for Future Technology (SRFC-IT1702-09). In addition, this work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2017R1D1A1B03035340, NRF-2017R1A6A1A03015642) and the Ministry of Science, ICT & Future Planning (NRF-2017M3C7A1043841).
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