Hydrogel-Immobilized Coacervate Droplets as Modular Microreactor Assemblies.

Immobilization of compartmentalized microscale objects in 3D hydrogels provides a step towards the modular assembly of soft functional materials with tunable architectures and distributed functionalities. Herein, we report the use of a combination of micro-compartmentalization, immobilization, and modularization to fabricate and assemble hydrogel-based microreactor assemblies comprising millions of functionalized polysaccharide-polynucleotide coacervate droplets. The heterogeneous hydrogels can be structurally fused by interfacial crosslinking and coupled as input and output modules to implement a UV-induced photocatalytic/peroxidation nanoparticle/DNAzyme reaction cascade that generates a spatiotemporal fluorescence read-out depending on the droplet number density, intensity of photoenergization, and chemical flux. Our approach offers a route to heterogeneous hydrogels with endogenous reactivity and reconfigurable architecture, and provides a step towards the development of soft modular materials with programmable functionality.