Proteinosome

Proteinosomes are synthetic cell-like compartments formed from amphiphilic protein–polymer conjugates that self-assemble into hollow vesicle structures in aqueous solutions. They serve as model systems for protocells, enabling study of compartmentalization and confined biochemical reactions without using living cells.

In typical constructions, a protein such as bovine serum albumin (BSA) is covalently linked to a polymer chain (for example poly(N-isopropylacrylamide) or polyethylene glycol). The resulting protein–polymer amphiphiles spontaneously organize into vesicle shells that enclose an aqueous interior. The shell is largely protein and polymer in composition, which can provide greater mechanical stability and distinct permeability properties compared with lipid-based membranes. The properties of the proteinosome shell can be tuned by changing the polymer length, crosslinking density, or by employing thermoresponsive polymers to modulate permeability with temperature.

Proteinosomes can encapsulate various cargo, including enzymes, nucleic acids, and nanoparticles, allowing in vitro biocatalysis, enzymatic cascades, and other reaction networks to proceed within a defined, cell-like space. Permeability of the shell supports diffusion of substrates while retaining larger cargo, and this selectivity can be adjusted through design parameters.

Applications of proteinosomes include fundamental studies of how compartmentalization affects biochemical processes, exploration of minimal cell-like systems, and potential uses in biocatalysis and biosensing. Limitations in the field involve achieving uniform size distribution, long-term stability, and scalable production, as well as controlling release and interaction with external environments.