Optical clearing has emerged as a powerful tool for volume imaging. Although volume imaging with immunostaining have been successful in many protocols, yet obtaining homogeneously stained thick samples remains challenging. Here, we propose a method for label-free imaging of brain slices by enhancing the regional heterogeneity of the optical properties using the tissue clearing principle. We used FxClear, a method for delipidation of brain tissue, to retain a larger proportion of lipids at the white matter (WM). Furthermore, the embedding media affected the contrasts for the lipid-rich or extracellular matrix-rich areas, depending on their chemical properties. Thus, we tailored clearing conditions for the enhancement of the refractive indices (RIs) differences between gray and WM, or several pathological features. RI differences can be imaged using conventional light microscopy or optical coherence tomography. We propose that our protocol is simple, reliable, and flexible for label-free imaging, easily implementable to routine histology laboratory.
Bibliographical noteFunding Information:
This research was supported by the Brain Research Program through the National Research Foundation (NRF), South Korea, which is funded by the Korean Ministry of Science, the ICT & Future Planning ( NRF-2015M3C7A1028790 , NRF-2017M3A9B3061308 , NRF-2018R1D1A1A02086190 and NRF-2019M3E5D2A01063939 ). We also thank Dr Lee, Ju-Hyun for her assistance to produce 3D images.
© 2021 The Author(s)
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