Correlative single-cell X-ray tomography and X-ray fluorescence imaging

Abstract X-ray tomography and x-ray fluorescence imaging are two non-invasive imaging techniques to study cellular structures and chemical element distributions, respectively. However, correlative X-ray tomography and fluorescence imaging for the same cell has yet to be routinely realized due to challenges in sample preparation and X-ray radiation damage. Here we report an integrated experimental and computational workflow for achieving correlative multi-modality X-ray imaging of a single cell. The method consists of the preparation of radiation-resistant single-cell samples using live-cell imaging-assisted chemical fixation and freeze-drying procedures, targeting and labeling cells for correlative x-ray tomography and x-ray fluorescence measurement, and computational reconstruction of the correlative and multi-modality images. With X-ray tomography, cellular structures including the overall structure and intracellular organelles are visualized, while X-ray fluorescence imaging reveals the distribution of multiple chemical elements within the same cell. Our correlative method demonstrates the feasibility and broad applicability of using X-rays to understand cellular structures and the roles of multiple chemical elements and related proteins in signaling and other biological processes.