SCO‐ph: Microfluidic Dynamic Phenotyping Platform for High‐Throughput Screening of Single Cell Acidification

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, it is developed a versatile microfluidic system for single cell optical pH analysis (SCO‐pH), which compartmentalizes single cells in 140‐pL droplets and immobilizes ≈40,000 droplets in a 2D 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, a cell‐impermeable pH probe is encapsulated and its fluorescence intensities are quantified. Using this approach, hyperglycolytic cells can be differentiated, and single‐cell heterogeneity in extracellular acidification dynamics can be concurrently observed. This high‐throughput system will be useful in applications that require dynamic phenotyping of single cells with significant heterogeneity.