Dynamic microcompartmentalization of giant unilamellar vesicles by sol gel transition and temperature induced shrinking/swelling of poly(N-isopropyl acrylamide)

Giant unilamellar vesicles (GUVs) were microinjected with aqueous solutions of poly(N-isopropyl acrylamide) (PNIPAAm). Temperature-dependent sol-gel phase transitions of the solutions, followed by shrinking and swelling of the resulting hydrogel, were studied in the presence of a variety of co-solutes within the GUV. Reversible formation of a dense, spherical hydrogel structure (compartment) was observed in all cases with defined shrinking/swelling behaviour at temperatures above the lower critical solution temperatures (LCSTs). Nanotube-mediated merging of two vesicles with thus formed compartments resulted in a single GUV with two internalized hydrogel structures. As an application example, we demonstrate how fluorescent nanoparticles can be immobilized in such gel structures.