15.9 Multicompartment Assembly

Multicompartment Assembly describes the construction of synthetic cell structures containing more than one distinct compartment, whether arranged as nested structures with one compartment enclosed inside another or as multiple internal compartments distributed in parallel within a single outer boundary. It extends the general compartment assembly process to structures with internal spatial organization beyond a single, undivided lumen.

Basic Organizational Strategies

Nested Compartment Assembly

Nested compartment assembly is the construction of a structure in which one compartment is fully enclosed within the interior of another, establishing a layered relationship in which an inner compartment's boundary and an outer compartment's boundary are both present and distinct from one another.

Parallel Internal Compartment Assembly

Parallel internal compartment assembly is the construction of a structure containing multiple separate internal compartments arranged side by side within a single outer boundary, rather than organized in a single nested sequence.

Specific Nested Architectures

Vesicle-in-Vesicle Assembly

Vesicle-in-vesicle assembly is the construction of a lipid vesicle enclosed within the lumen of a larger lipid vesicle, producing a doubly membrane-bound structure with two concentric but independently formed bilayer boundaries.

Droplet-in-Vesicle Assembly

Droplet-in-vesicle assembly is the construction of an emulsion or particle-stabilized droplet enclosed within the lumen of a lipid vesicle, combining an interfacially stabilized inner compartment with a bilayer-bound outer boundary.

Coacervate-in-Vesicle Assembly

Coacervate-in-vesicle assembly is the construction of a phase-separated coacervate droplet formed within the aqueous lumen of a lipid vesicle, combining a boundary-free, macromolecule-concentrating inner compartment with a discrete outer boundary.

Vesicle-in-Coacervate Assembly

Vesicle-in-coacervate assembly is the construction of one or more lipid vesicles embedded within the dense phase of a coacervate droplet, combining a discrete, bilayer-bound inner compartment with a boundary-free outer environment.

Protein Shell-in-Vesicle Assembly

Protein shell-in-vesicle assembly is the construction of a rigid protein shell compartment enclosed within the lumen of a lipid vesicle, combining a structurally defined, molecularly selective inner compartment with a flexible outer bilayer boundary.

Assembly Process Considerations

Sequential Internal Compartment Enclosure

Sequential internal compartment enclosure is a multicompartment assembly approach in which an inner compartment is fully formed first, and a second, outer boundary is subsequently formed around it, establishing the nested relationship in two clearly separated steps.

Fusion-Mediated Compartment Combination

Fusion-mediated compartment combination is a multicompartment assembly approach in which separately formed compartments are brought together and merged, incorporating one compartment into another through a fusion event rather than through sequential enclosure during initial formation.

Internal Compartment Positioning

Internal compartment positioning describes where within the outer boundary's lumen an inner compartment or compartments end up located, which can vary from centrally placed to peripherally distributed depending on the specific assembly approach used.

Internal Compartment Number Control

Internal compartment number control describes the degree to which the assembly process can be directed to produce a specific, intended number of internal compartments per outer structure, as opposed to producing a variable and uncontrolled number.

Outcomes and Retention

Internal Compartment Retention

Internal compartment retention describes whether internal compartments, once enclosed, remain intact and enclosed within the outer boundary over time, rather than escaping, rupturing, or otherwise losing their distinct identity within the larger structure.

Multicompartment Topology Control

Multicompartment topology control describes the degree to which the overall spatial arrangement of compartments, whether nested, parallel, or a combination of both, can be reliably and predictably achieved through a given assembly approach.

Practical Considerations

Multicompartment Assembly Yield

Multicompartment assembly yield describes the proportion of assembly attempts that successfully produce the intended multicompartment structure, as opposed to producing single compartments, compartments with the wrong internal architecture, or failed structures.

Multicompartment Assembly Complexity

Multicompartment assembly complexity describes the additional procedural and material demands introduced by constructing a nested or parallel multicompartment structure relative to a single-compartment assembly process, reflecting that multicompartment approaches generally require more assembly steps and tighter process control.