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Updated: Dec 28, 2025
Spot Variation Fluorescence Correlation Spectroscopy for Analysis of Molecular Diffusion at the Plasma Membrane of Living Cells
Published on: November 12, 2020
Measuring diffusion exchange across the cell membrane with DEXSY (Diffusion Exchange Spectroscopy)
James O Breen-Norris1,2, Bernard Siow1,2,3, Claire Walsh1
1Centre for Advanced Biomedical Imaging, Division of Medicine, University College London, London, UK.
Introduction:
To combine numerical simulations, in vitro and in vivo experiments to evaluate the feasibility of measuring diffusion exchange across the cell membrane with diffusion exchange spectroscopy (DEXSY).
Methods:
DEXSY acquisitions were simulated over a range of permeabilities in nerve tissue and yeast substrates. In vitro measurements were performed in a yeast substrate and in vivo measurements in mouse tumor xenograft models, all at 9.4 T.
Results:
Diffusion exchange was observed in simulations over a physiologically relevant range of cell permeability values. In vitro and in vivo measures also provided evidence of diffusion exchange, which was quantified with the Diffusion Exchange Index (DEI).
Conclusions:
Our findings provide preliminary evidence that DEXSY can be used to make in vivo measurements of diffusion exchange and cell membrane permeability.
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