MAGNIFY: molecule anchorable gel-enabled nanoscale in-situ fluorescence microscopy for nanoscale imaging of biomolecules

Abstract

Expansion microscopy (ExM) is a powerful imaging strategy that offers a low-cost solution for interrogating biological systems at the nanoscale using conventional optical microscopes. It achieves this by physically and isotropically magnifying preserved biological specimens embedded in a cross-linked water-swellable hydrogel. However, most reported techniques are unable to preserve endogenous epitopes due to strong protease digestion used to expand samples. In addition, these protocols rely on mechanically fragile hydrogels that only expand by at most 4.5× linearly. We present a new ExM framework, Molecule Anchorable Gel-enabled Nanoscale In-situ Fluorescence MicroscopY (MAGNIFY), that exhibits a broad retention of nucleic acids, proteins, and lipids without the need for a separate anchoring step. By using a mechanically sturdy hydrogel, MAGNIFY is capable of expanding biological specimens up to 11×. This facilitates nanoscale imaging (~25-nm effective resolution) using an ∼280-nm diffraction-limited objective lens on a conventional optical microscope and can be furthered to ~15 nm effective resolution if combined with computational methods such as Super-resolution Optical Fluctuation Imaging (SOFI). Here, we demonstrate that MAGNIFY provides a generalized solution for imaging nanoscale subcellular features of a broad range of biological specimens. We also show that MAGNIFY provides a novel, accessible tool for improving the precision, utility, and generality of nanoscopy.