Hydrogen Bonding-Driven Adaptive Coacervates as Protocells

Coacervation based on liquid-liquid phase separation (LLPS) has been widely used for the preparation of artificial protocells and to mimic the dynamic organization of membrane-free organelles. Most complex synthetic coacervates are formed through electrostatic interactions but cannot withstand high ionic strength conditions (>0.1 M). Alternative components and driving forces are highly desired for the formation of natural organelles to overcome the drawbacks of traditional coacervates. Herein, hydrogen bonding-driven adaptive coacervates are reported via the complexation of poly(ethylene glycol) (PEG) and tannic acid (TA). The LLPS behavior of these adaptive coacervates is dependent on the concentration and mass ratio of PEG and TA, which can be used to tune the size of coacervates ranging from 70 nm to 10 μm as well as the morphology of isotropic particles and hollow capsules. Coacervates are stable at high ionic concentrations up to 1 M and can serve as protocells to mimic cellular behaviors including metabolism (e.g., nutrient uptake), phagocytosis, and membrane fusion. The reported approach provides a platform for the rational design of hydrogen bonding-driven coacervates with controllable size and morphology, offering potential applications in protocell construction and therapeutic delivery.