Controlled deprotection and release of a small molecule from a compartmented synthetic tissue module

Synthetic tissues built from communicating aqueous droplets offer potential applications in biotechnology, however, controlled release of their contents has not been achieved. Here we construct two-droplet synthetic tissue modules that function in an aqueous environment. One droplet contains a cell-free protein synthesis system and a prodrug-activating enzyme and the other a small-molecule prodrug analog. When a Zn2+-sensitive protein pore is made in the first droplet, it allows the prodrug to migrate from the second droplet and become activated by the enzyme. With Zn2+ in the external medium, the activated molecule is retained in the module until it is released on-demand by a divalent cation chelator. The module is constructed in such a manner that one or more, potentially with different properties, might be incorporated into extended synthetic tissues, including patterned materials generated by 3D-printing. Such modules will thereby increase the sophistication of synthetic tissues for applications including controlled multidrug delivery.