Multi-Stimuli Responsive Magneto-Coacervate Droplets for Selective Molecular Enrichment and Programmable Manipulation

Coacervate droplets formed via liquid-liquid phase separation offer unique opportunities as microreactors and delivery vehicles due to their ability to selectively concentrate biomolecules and support biochemical reactions. However, their passive nature severely restricts precise spatial and temporal control, posing barriers to practical implementation. Here, we report magneto-coacervate droplets constructed from gelatin, poly(diallyldimethylammonium chloride) (PDDA), and superparamagnetic Fe₃O₄@SiO₂ nanoparticles. These magneto-coacervate droplets exhibit reversible sol-gel transitions controlled by temperature and pH, tunable surface charge properties for electrostatically driven molecular enrichment, and precise three-dimensional manipulation under external magnetic fields. These magneto-coacervate droplets can serve as multifunctional platforms, greatly increasing the practical use of phase-separated microreactors in environmental remediation, biochemical processing, and targeted biomedical interventions. Demonstrated applications include efficient capture and recycling of microplastic pollutants, magnetically enhanced catalytic enzyme cascades with reaction rates 2-3 times higher than those of conventional methods, and targeted vascular embolization through controlled in situ gelation.