Liquid-cell TEM images associated with the publication titled "Facile Hermetic TEM Grid Preparation for Molecular Imaging of Hydrated Biological Samples at Room Temperature" (Kong, L., Liu, J., Zhang, M., et al., Nat. Commun. 14, 5641, 2023. https://doi.org/10.1038/s41467-023-41266-x)

Room-Temperature Transmission Electron Micrographs of GroEL in Aqueous Buffer :  Room-temperature transmission electron microscopy (TEM) micrographs were obtained from GroEL molecules suspended in aqueous buffer and sealed between two Formvar films coated on TEM grids. Detailed experimental procedures are described in the associated publication: https://doi.org/10.1038/s41467-023-41266-x.

In well-preserved regions, GroEL molecules are evenly distributed and clearly visible. However, image quality varies across the grid due to local inconsistencies in sample conditions. In some areas, partial drying has occurred; in others, the buffer layer is too thick to allow proper imaging, or the protein has been damaged by electron beam exposure. Additional limitations on image quality arise from sample motion, including drift caused by beam-induced liquid movement and grid instability.

Despite these challenges, the characteristic structural features of GroEL—consistent with the known crystal structure (PDB ID: 1XCK, https://doi.org/10.1016/j.str.2004.05.006)—are clearly observable in several micrographs. These observations demonstrate that high-resolution protein structures can be visualized at room temperature without the need for cryogenic cooling, staining, or chemical fixation.

Partially dried regions are identifiable by the presence of salt crystals precipitated from the buffer. Progressive radiation damage is evident, beginning with the loss of fine structural features, followed by bubbling of protein molecules and gas formation due to radiolysis of water. This phenomenon is consistent with previously reported bubbling effects in hydrated samples observed by cryo-EM, as described by Glaeser (https://doi.org/10.1016/bs.mie.2016.04.010).