Peptide-based artificial cytoskeleton enhances colocalized cascade reactions in cell-like microreactors

We report the formation of an artificial cytoskeleton within droplet-based protocells, which dramatically increases the efficiency of a cascade reaction. The cytoskeleton is formed via self-assembly of a short peptide phenylalanine-phenylalanine-methionine (FFM) in the confinement of cell-sized water-in-oil droplets. FFM undergoes coacervation, followed by fiber formation when increasing the pH value from 5.3 to 8, resulting in the generation of a fibrous network within the droplets, resembling a cytoskeleton. This cytoskeleton can bind proteins and enzymes on it, such as bovine albumin serum, glucose oxidase and horseradish peroxidase, resulting in the co-localization of the enzymes on the fiber network, which leads to the enhancement of cascade reaction efficiency. The efficiency of the cascade is even further increased when reducing the size of the microreactors from 86 µm to 49 µm and 31 µm. This artificial cytoskeleton mimics an important feature of the natural cytoskeleton, providing anchorage and colocalization for enzymes involved in cascade reactions.