Fig. 1. (A) Schematic illustration of the coacervate-in-coacervate synthetic procedure via a layer-by-layer assembly method. Step 1: PDDA/DNA coacervate microdroplets were synthesized through electrostatic assembly of PDDA and DNA polyelectrolytes. Step 2: PDDA/DNA@CM-dextran coacervate microdroplets were formed by the assembly of CM-dextran on positively charged PDDA/DNA coacervates. Step 3: PDDA/DNA@CM-dextran/DEAE-dextran coacervates were formed by the assembly of DEAE-dextran on negatively charged PDDA/DNA@CM-dextran coacervates. (B, C) Schematic representation of the spatial organization of the coacervate-in-coacervate enzymatic cascade. The GOx, HRP, and CAT enzymes could be immobilized in the multi-compartment microdroplets through synchronous assembly. (B) Case I: GOx/HRP and CAT were all encapsulated in the inner compartments of the coacervates. (C) Case II: GOx/HRP and CAT were separately encapsulated in the inner and outer compartments of the coacervates, respectively.