Bottom-up construction of artificial cells is pivotal for investigating the functional and structural evolution of protocell systems. Here, a streamlined methodology is reported for constructing a protocell model that exhibits pH-adaptive responsiveness and functions as an efficient microreactor for cascade biochemical reactions. These protocells are engineered through liquid–liquid phase separation (LLPS) of poly(diallyldimethylammonium chloride) (PDDA) and adenosine triphosphate (ATP), yielding coacervate microdroplets that serve as nucleation sites for spontaneous self-assembly of phospholipid semipermeable membranes. By tuning the pH environment of the membranized protocells, the hydrolytic property of ATP under acidic conditions modulates the surface charge density of coacervates, triggering elevated surface potential and altered interfacial tension, which ultimately induce secondary phase separation inside the protocells to yield dynamically reconfigurable microcompartments. Notably, introduction of small-molecule substrates triggers enzymatic reactions within the molecularly crowded lumen of the protocells, which in turn drives pH-mediated micro-compartmentalization, enabling the coupling of biocatalysis with structural dynamics. This protocell model, characterized by programmable dynamic micro-compartmentalization, offers distinct advantages for applications in cellular mimicry, synthetic protobiology, and the development of artificial biomolecular microreactors.
Mengqing Chen,Guoliang Liu,Ming Zhang,Yanyan Li,Xinlin Hong,Hengquan Yang
The desire for exploration of cellular functional mechanisms has substantially increased the rapid development of artificial cells. However, the construction of synthetic cells with high organizational complexity remains challenging due to the lack of facile approaches ensuring dynamic multi-compartments of cytoplasm and stability of membranes in protocells. Herein, a stable coacervate-in-Pickering emulsion protocell model comprising a membraneless coacervate phase formed by poly- l -lysine (PLys) and adenosine triphosphate (ATP) encapsulated in Pickering emulsion is put forward only through simple one-step emulsification. The dynamic distribution of intracellular components (coacervates in this protocell model) can be manipulated by changes in temperature or pH. This coacervate-in-Pickering emulsion protocell system exhibits repeatable cycle stability in response to external stimuli (at least 24 cycles for temperature and 3 cycles for pH). By encapsulating antagonistic enzymes into coacervates, glucose oxidase (GOx) and urease as an example, the control of local enzyme concentration is achieved by introducing glucose and urea to adjust the pH value in Pickering emulsion droplets. This hybrid protocell model with programmatically dynamic microcompartmentation and sufficient stability is expected to be further studied and applied in cellular biology, facilitating the development of lifelike systems with potential in practical applications.
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