A biocompatible surfactant film for stable microfluidic droplets

Droplets serve as practical compartments for the analysis of individual biological species like nucleic acids and single cells due to the small size and ease of production of droplets. However, coalescence among droplets is a persistent challenge that often precludes the application of droplet-based techniques, particularly in cases when droplets are subject to harsh conditions or must remain stable for extended periods of time. Here, we introduce a versatile film-forming surfactant that forms robustly stable droplets. The film is formed at the droplet interface through covalent interactions between a custom polymer in a fluorinated phase and a diol-containing macromolecule in an aqueous phase. The film can stabilize droplets during polymerase chain reaction (PCR) and is biocompatible. The surfactant provides an archetype for new surfactant chemistries employing random copolymers and interfacial association.