In bottom-up synthetic biology, compartmentalisation of bioactive materials within artificial cells is used to mimic the ways biological cells segregate and manage their cellular activity and/or communicate with other cells. In phospholipid-based artificial cell models, compartmentalisation of biomolecules is achieved by encapsulating them into small nano-sized vesicles stabilised by a unilamellar lipid bilayer. These compartments are then encapsulated into micro-scaled unilamellar vesicles – bioreaction-hosting artificial cells. Although this artificial compartmentalisation hierarchy resembles a biologically ubiquitous one, in natural cells compartmentalisation is a dynamic process as organelles, membrane-bound cavities hosting biochemical reactions, change shape, size, and location within the cell. In some instances, membrane-less organelles form in response to external triggers, helping the biological cells combat cellular stress. These examples show how important dynamic compartmentalisation is to maintain optimal cellular activities.
In phospholipid-based systems created to mimic cellular processes, compartmentalisation remains static. Organelle mimics diffuse throughout the hosting giant vesicle lumen without control over their spatial organisation. This lack of control over artificial cell compartmentalisation limits the researcher’s ability to create more life-like cells. Strategies for gaining control over dynamic cell compartmentalisation could potentially enable further functionalisation of artificial cells and therefore their application potential in constructing sophisticated micromachines such as nested vesicle microreactors and targeted drug delivery vehicles. In this thesis we created a suite of compartmentalised architectures with dynamic features. We have explored electrostatic interactions between oppositely charged phospholipid vesicles to create hierarchical artificial cells with defined sub-compartment spatial organisations that can be controlled using chemical and mechanical external stimuli.