FLUID-CELL: Flow-enabled Light and Ultrastructural Imaging Device for Correlative Electron and Light Localization.

We present a novel microfluidic flow cell, or Flow-enabled Light and Ultrastructural Imaging Device for Correlative Electron and Light Localization (FLUID-CELL), that connects fluorescence light microscopy (FLM) and cryo-electron microscopy (cryo-EM) for advanced biological imaging and ultrastructural and structural analyses. The design of the FLUID-CELL features a precisely engineered microchannel that maintains native cell culturing conditions, supporting correlation and enabling real-time observation by FLM, as well as subsequent cryo-EM analysis. In this study, this device enabled practical FLM imaging over extended experimental periods, consistent sample handling, and the ability to perform correlative imaging. This capability connects dynamic cellular events imaged by fluorescence light microscopy with high-resolution ultrastructural data collected with cryo-EM. Our dual-modality approach streamlines the workflow and opens new possibilities for investigating the relationship between cellular function and molecular architecture at the nanoscale.