Facile hermetic TEM grid preparation for molecular imaging of hydrated biological samples at room temperature

Although structures of vitrified supramolecular complexes have been determined at near-atomic resolution, elucidating in situ molecular structure in living cells remains a major challenge. Here, we employ a novel yet simple liquid-cell technique, previously developed for real-time visualization of dynamics at a liquid-gas interface, to image wet biological samples. Due to the scattering effects from the liquid phase, the transmission electron micrographs exhibit amplitude contrast comparable to that observed in negatively stained samples. We successfully resolve subunits within the protein complex GroEL, which has been imaged in a buffer solution at room temperature. Additionally, we capture various stages of virus cell entry, which have limited structural information available due to their transient nature. To further analyze the morphological details, we employ the technique of individual particle electron tomography (IPET). These results demonstrate the potential of this approach as a valuable and cost-effective technique that complements other microscopy techniques in addressing important biological questions at the molecular level.