Towards high throughput production of artificial egg oocytes using microfluidicsElectronic supplementary information (ESI) available: Five Supplementary Figures and Two Supplementary Movies. See DOI: 10.1039/c0lc00046a

The production of micron-size droplets using microfluidic tools offers new opportunities to carry out biological assays in a controlled environment. We apply these strategies by using a flow-focusing microfluidic device to encapsulate Xenopus egg extracts, a biological system recapitulating key events of eukaryotic cell functions in vitro . We present a method to generate monodisperse egg extract-in-oil droplets and use high-speed imaging to characterize the droplet pinch-off dynamics leading to the production of trains of droplets. We use fluorescence microscopy to show that our method does not affect the biological activity of the encapsulated egg extract by observing the self-organization of microtubules and actin filaments, two main biopolymers of the cell cytoskeleton, encapsulated in the produced droplets. We anticipate that this assay might be useful for quantitative studies of biological systems in a confined environment as well as high throughput screenings for drug discovery. We use microfluidic strategies to encapsulate biologically functional eukaryotic cytoplasm ( Xenopus egg extracts) in micron-sized droplets. Our approach provides an alternative solution for drug screening using a phenotype-based assay.