Hydrogels dehydrate embedded liposomes

Amphiphiles self-assemble into different structures depending on packing and environment. The effect of hydrogels on amphiphile self-assembly—particularly liposome self-assembly—has not been extensively studied. This is relevant for both the design of new scaffold materials for cell growth and the understanding of how drug carriers interact with the extracellular matrix. In this presentation, we will show recent Small-Angle X-ray Scattering (SAXS) data demonstrating that when liposomes are incorporated into polyethylene glycol (PEG) hydrogels, they suffer significant restructuring. Specifically, in addition to a characteristic correlation length of 14 nm for the crosslinked hydrogel, Bragg peaks are detected, indicating that liposomes have transformed into a tight stack of lipid bilayers with interlamellar separation of 5.7 nm. These results demonstrate that hydrogels have a strong influence on liposome self-assembly. We hypothesize that the hydrophilic PEG hydrogel osmotically absorbs a significant volume of water, inducing a transformation of liposomes into multilamellar bodies. When liposomes are protected with a PEG-moiety corona, the influence of the surrounding hydrogel appears to be damped.