Abstract
Studies on the dynamics of single cell phenotyping have been hampered by the lack of quantitative high-throughput metabolism assays. Extracellular acidification, a prominent phenotype, yields significant insights into cellular metabolism, including tumorigenicity. Here, we develop a versatile microfluidic system for single cell optical pH analysis (SCO-pH), which compartmentalizes single cells in 140-pL droplets and immobilizes approximately 40,000 droplets in a two-dimensional array for temporal extracellular pH analysis. SCO-pH distinguishes cells undergoing hyperglycolysis induced by oligomycin A from untreated cells by monitoring their extracellular acidification. To facilitate pH sensing in each droplet, we encapsulate a cell-impermeable pH probe whose fluorescence intensities are quantified. Using this approach, we can differentiate hyperglycolytic cells and concurrently observe single cell heterogeneity in extracellular acidification dynamics. This high-throughput system will be useful in applications that require dynamic phenotyping of single cells with significant heterogeneity.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Could you please add Acknowledgements, Conflicts of interest, and Author contribution as below, after removing the present Acknowledgements? Thank you very much. Acknowledgements Research reported in this publication was supported by the National Human Genome Research Institute of the National Institutes of Health under Award Number RM1HG010023. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. E.A.L.P. is funded through the University of Pennsylvania Fontaine Society. Conflicts of Interest The authors declare no conflict of interest. Author Contributions H.J., S.H.H., D.L., and J.K. designed the study. H.J. implemented experiments, analyzed the data, and wrote the manuscript. E.A.L.P. and B.L. created the image analysis pipeline. D.K. wrote the image file sorting script. The other authors assisted with the experiments and discussed the results. All authors have read and approved the final version of the manuscript.
