A highly homogeneous polymer composed of tetrahedron-like monomers for high-isotropy expansion microscopy
Yu, Chih-Chieh Jay
Piatkevich, Kiryl D.
Neve, Rachael L.
Munro, James B.
Boyden, Edward S.
UMass Chan AffiliationsDepartment of Microbiology and Physiological Systems
Biochemistry, Biophysics, and Structural Biology
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AbstractExpansion microscopy (ExM) physically magnifies biological specimens to enable nanoscale-resolution imaging using conventional microscopes. Current ExM methods permeate specimens with free-radical-chain-growth-polymerized polyacrylate hydrogels, whose network structure limits the local isotropy of expansion as well as the preservation of morphology and shape at the nanoscale. Here we report that ExM is possible using hydrogels that have a more homogeneous network structure, assembled via non-radical terminal linking of tetrahedral monomers. As with earlier forms of ExM, such 'tetra-gel'-embedded specimens can be iteratively expanded for greater physical magnification. Iterative tetra-gel expansion of herpes simplex virus type 1 (HSV-1) virions by ~10x in linear dimension results in a median spatial error of 9.2 nm for localizing the viral envelope layer, rather than 14.3 nm from earlier versions of ExM. Moreover, tetra-gel-based expansion better preserves the virion spherical shape. Thus, tetra-gels may support ExM with reduced spatial errors and improved local isotropy, pointing the way towards single-biomolecule accuracy ExM.
Gao R, Yu CJ, Gao L, Piatkevich KD, Neve RL, Munro JB, Upadhyayula S, Boyden ES. A highly homogeneous polymer composed of tetrahedron-like monomers for high-isotropy expansion microscopy. Nat Nanotechnol. 2021 Jun;16(6):698-707. doi: 10.1038/s41565-021-00875-7. Epub 2021 Mar 29. PMID: 33782587; PMCID: PMC8197733. Link to article on publisher's site