Quantitative Cell-Based Reporter Gene Assays Using Droplet-Based Microfluidics

SummaryWe used a droplet-based microfluidic system to perform a quantitative cell-based reporter gene assay for a nuclear receptor ligand. Single Bombyx mori cells are compartmentalized in nanoliter droplets which function as microreactors with a >1000-fold smaller volume than a microtiter-plate well, together with eight or ten discrete concentrations of 20-hydroxyecdysone, generated by on-chip dilution over 3 decades and encoded by a fluorescent label. The simultaneous measurement of the expression of green fluorescent protein by the reporter gene and of the fluorescent label allows construction of the dose-response profile of the hormone at the single-cell level. Screening ∼7500 cells per concentration provides statistically relevant data that allow precise measurement of the EC50 (70 nM ± 12%, α = 0.05), in agreement with standard methods as well as with literature data.

Graphical AbstractFigure optionsDownload full-size imageDownload high-quality image (139 K)Download as PowerPoint slideHighlights► Cell-based reporter gene assay in droplet-based microfluidics ► Hybrid system combining flow cytometry and compartmentalization ► Quantitative measurement of dose-response profile at the single-cell level ► Statistical analysis of the response of individual cells in a population