In this study, we encapsulated a DNA Y-motif solution in a W/O microdroplet. We investigated the pattern-formation dynamics that emerged from the interaction between DNA coacervates and the lipid monolayer interface of the W/O microdroplet (Figure ). The lipid monolayer interface is composed of two types of lipids: a zwitterionic lipid, 1,2-dioleoyl-sn-glycero-3phosphocholine (DOPC) and a cationic lipid, 1-oleoyl-2-{6-[(7-nitro-2-1,3-benzoxadiazol-4yl)amino]hexanoyl}-sn-glycero-3-phosphocholine (DOTAP). The total lipid concentration was 2 mM. By the annealing of the emulsion of W/O microdroplets from 95°C (> 𝑇 !" ) to 20°C (< 𝑇 $ ), the DNA coacervates formed by self-assembly from the DNA Y-motifs on the microdroplet interface via electrostatic interaction between the anionic DNA molecules and the cationic interfacial lipids results in the formation of porous/non-porous structures of capsular DNA coacervates . It has been reported that the wettability of polymers to a microdroplet interface affects the pattern-formation of a polymer gel at the microdroplet interface . In this study, we investigated the dependence of the pattern-formation of capsular DNA coacervates on the wettability of the DNA coacervates to the interface by changing the ratio of DOTAP composition in total lipid from 100% to 50% (Figure ). When DOPC:DOTAP = 0:100, only non-porous structures of capsular DNA coacervates were observed because the wettability of the DNA coacervates to the interface was strong. As the ratio of the DOTAP decreased, the percentage of porous structures of the capsular DNA coacervates increased due to the wettability of the DNA coacervate to the interface became weaker. Hereafter, the lipid composition in the oil phase was fixed to DOPC:DOTAP = 50:50 in all experiments.