Rapid high resolution 3D imaging of expanded biological specimens with lattice light sheet microscopy.

Expansion microscopy was invented to surpass the optical diffraction limit by physically expanding biological specimens with swellable polymers. Due to the large sizes of expanded specimens, 3D imaging techniques that are capable to acquire large volumetric data rapidly at high spatial resolution are therefore required for expansion microscopy. Lattice light sheet microscopy (LLSM) was developed to image biological specimens rapidly at high 3D spatial resolution by using a thin lattice light sheet for sample illumination. However, due to the current limitations of LLSM mechanism and the optical design of LLS microscopes, it is challenging to image large expanded specimens at isotropic high spatial resolution using LLSM. To address the problem, we first optimized the sample preparation and expansion procedure for LLSM. Then, we implement a tiling lattice light sheet method to minimize sample translation during imaging and achieve much faster 3D imaging speed at high spatial resolution with more isotropic performance. Taken together, we report a general and improved 3D super-resolution imaging method for expanded samples.