Figure 1 (IMAGE) Institute for Basic Science Caption (a) Fe3+ ion triggers membrane fusion in exosomes tailored with catechol (CEx). The formation of a metal-catechol complex brings the exosomes into close proximity and enables fusion. Different reactants in each exosome are then encapsulated together, promoting mixing and triggering reactions inside the fused exosomes (FEx). (b) The microfluidic device designed for generating water-in-oil droplet reactors at the flow-focusing junction. The two aqueous phases (CEx and metal salt) meet and are delivered into the oil stream (1% surfactant PFPE-PEG in FC-40) to break the liquid into droplets. (c) Average size of unfused exosomes (CEx-1: 121 ± 8 nm, CEx-2: 123 ± 5 nm) and fused exosomes (FEx: 265 ± 14 nm). Credit Institute for Basic Science Usage Restrictions Attribution Required License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.