Miniaturising the laboratory in emulsion droplets

Biochemical and genetic assays can be both miniaturized and parallelized by compartmentalization in living cells. In vitro compartmentalization (IVC) offers an alternative strategy based on partitioning reactions in water droplets dispersed to form microscopic compartments in water-in-oil emulsions. The cell-like volumes of these compartments (as low as one femtolitre), the ability to freely determine and regulate their content and the large number of compartments (>1010 per millilitre emulsion) have provided the basis for a range of new, ultra-high-throughput, cell-free technologies. This review describes the scope and potential of IVC in areas such as in vitro evolution of proteins and RNAs, cell-free cloning and sequencing, genetics, genomics, and proteomics.