Invasion and Defense Interactions between Enzyme-Active Liquid Coacervate Protocells and Living Cells

The design and construction of mutual interaction models between artificial microsystems and living cells have the potential to open a wide range of novel applications in biomedical and biomimetic technologies. In this study, an artificial form of invasion-defense mutual interactions is established in a community of glucose oxidase (GOx)-containing liquid coacervate microdroplets and living cells, which interact via enzyme-mediated reactive oxygen species (ROS) damage. The enzyme-containing coacervate microdroplets, formed via liquid-liquid phase separation, act as invader protocells to electrostatically bind with the host HepG2 cell, resulting in assimilation. Subsequently, the glucose oxidation in the liquid coacervates initiates the generation of H₂ O₂ , which serves as an ROS resource to block cell proliferation. As a defense strategy, introduction of catalase (CAT) into the host cells is exploited to resist the ROS damage. CAT-mediated decomposition of H₂ O₂ leads to the ROS scavenging and results in the recovery of cell viability. The results obtained in the current study highlight the remarkable opportunities for the development of mutual interacting communities on the interface of artificial protocells/living cells. They also provide a new approach for engineering cellular behaviors through exploiting artificial nonliving microsystems.