Fluorosurfactants for stabilizing single- and double-emulsion droplets

The invention provides a fluorosurfactant composition for use in stabilising emulsions, in particular emulsions comprising single or double-emulsion droplets; as well as improved methods for manufacture of the fluorosurfactant; wherein the surfactant comprises a perfluorocarbon chain amide covalently linked to a polymer of ethylene oxide and propylene oxide. The invention also provides methods for single-cell resolution cell killing- and cell secretion-assays based on droplets stabilised by the fluorosurfactant composition.