Ultrahigh Transparent and Toughness Copolymer Eutectogels via Phase Separation for Fast Tissue Clearing and 2D/3D Imaging

Gel-based tissue clearing technologies represent a significant advancement in three-dimensional imaging. However, the challenge of achieving consistent high resolution across large tissue samples remains an issue. We present a phase-separated eutectogel constructed through radical copolymerization of acrylamide and <i>N</i>,<i>N</i>-dimethylacrylamide in a eutectic solvent (antipyrine/erythritol/imidazole) (AEI/ES) with dynamically tunable polymer-solvent interactions. The prepared eutectogel exhibits high transparency (above 90%) and facilitates rapid clearing of thick tissues and whole organs to a high degree of transparency, while preserving their original size and compatibility with multiple fluorescence. The eutectogel demonstrates high strength (4.2 MPa), favorable Young's modulus (9.8 MPa), and large toughness (0.78 MJ m^-3). The strong mechanical strength of the eutectogel improves tissue strength by more than 120-fold, facilitating the procurement of high-resolution two-dimensional images of cells and subcellular structures. It also offers a wide range of dynamic tunability, thereby providing a universal platform for diverse applications spanning biomedicine to tissue engineering.