Presentation Information
[P01-047]Leveraging Hydrogels to Programme Cargo Transport and Membrane Dynamics in Liposome-Based Synthetic Cells
○Aileen Cooney1 (1. Institute of Science Tokyo (Visiting from Imperial College London) (Japan))
Keywords:
Hydrogel,liposome,artificial cell,membrane transport,polymer swelling
Biological cells can be considered as highly specialised living micromachines, with a dynamic plasma membrane and cytoskeleton that enable sensing and responding to the environment. The drive to emulate some of the sophisticated behaviours of living cells has led to the development of synthetic cells, which comprise microscale assemblies of biomolecules and non-living components. Liposomes are often used as simplified models of the plasma membrane, although the complexity of the cytoskeleton is not recapitulated in such systems. The use of synthetic or natural polymers offers a route towards designing a cytoskeletal-like scaffold inside synthetic cells.
Here we demonstrate that coupling liposomes to an internal hydrogel scaffold generates emergent membrane rupture and resealing dynamics, and consequently enables protein-free transport and membrane repair. Giant phospholipid vesicles are first prepared encapsulating thiolated tetra-PEG subunits in the lumen, followed by in situ gelation via tetra-PEG crosslinking disulfide bond formation and tetra-PEG crosslinking. The internal hydrogel is seen to mechanically couple to the membrane, providing a simple physical mimic of the cell cortex that modulates membrane tension and lateral lipid mobility, with a measurable reduction in phospholipid diffusion seen using FRAP.
Osmotic swelling of the confined hydrogel causes an increase in membrane tension, leading to membrane rupture and the release of encapsulated cargo or the uptake of external solutes. Subsequent relaxation of membrane tension via gel deswelling promotes the resealing of the membrane ruptures, restoring membrane integrity. The swelling and rupture rate of the lipid membrane can be tuned by varying the density of the encapsulated hydrogel and the induced osmotic pressure, allowing triggered release or uptake of various cargo. Importantly, the mechanically induced pores are sufficiently large to permit exchange of macromolecular cargo, including proteins, at scales inaccessible to conventional reconstituted pores.
The integration of multiple material classes in a hybrid gel-liposome system therefore provides a method to modulate and probe membrane tension, with exciting potential in cargo transport and control over membrane dynamics.
Here we demonstrate that coupling liposomes to an internal hydrogel scaffold generates emergent membrane rupture and resealing dynamics, and consequently enables protein-free transport and membrane repair. Giant phospholipid vesicles are first prepared encapsulating thiolated tetra-PEG subunits in the lumen, followed by in situ gelation via tetra-PEG crosslinking disulfide bond formation and tetra-PEG crosslinking. The internal hydrogel is seen to mechanically couple to the membrane, providing a simple physical mimic of the cell cortex that modulates membrane tension and lateral lipid mobility, with a measurable reduction in phospholipid diffusion seen using FRAP.
Osmotic swelling of the confined hydrogel causes an increase in membrane tension, leading to membrane rupture and the release of encapsulated cargo or the uptake of external solutes. Subsequent relaxation of membrane tension via gel deswelling promotes the resealing of the membrane ruptures, restoring membrane integrity. The swelling and rupture rate of the lipid membrane can be tuned by varying the density of the encapsulated hydrogel and the induced osmotic pressure, allowing triggered release or uptake of various cargo. Importantly, the mechanically induced pores are sufficiently large to permit exchange of macromolecular cargo, including proteins, at scales inaccessible to conventional reconstituted pores.
The integration of multiple material classes in a hybrid gel-liposome system therefore provides a method to modulate and probe membrane tension, with exciting potential in cargo transport and control over membrane dynamics.
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