Giant Lipid Vesicle Formation Using Vapor-Deposited Charged Porous Polymers

Abstract

In this study, we prepare giant lipid vesicles using vapor-deposited charged microporous poly(methacrylic acid- co-ethylene glycol diacrylate) polymer membranes with different morphologies and thicknesses. Our results suggest that vesicle formation is favored by thinner, more structured porous hydrogel substrates. Electrostatic interactions between the polymer and the lipid head groups affect vesicle yield and size distribution. Repulsive electrostatic interactions between the hydrogel and the lipid head groups promote vesicle formation; attractive electrostatic interactions suppress vesicle formation. Ionic strength and sugar concentration are also major parameters affecting the yield and size of giant vesicles. The presence of both ions and sugars in the hydration buffer results in increased vesicle yields. These results indicate that lipid-polymer interactions and osmotic effects in addition to the substrate morphology and surface charge are key factors affecting vesicle formation. Our data suggest that surface chemistry should be designed to tune electrostatic interactions with the lipid mixture of interest to promote vesicle formation. This vapor-deposited hydrogel fabrication technique offers tunability over the physicochemical properties of the hydrogel substrate for the production of giant vesicles with different sizes and compositions.

Nanoscale control by chemically vapour-deposited polymers

“…133,134 For all-dry membrane fabrication, monomers were first solidified on a cooled reactor stage in the absence of an initiator. 135,136 The resulting porous microstructures were next infiltrated by an iCVD polymer grown from the same monomer. Sublimation of the solid monomer yields freestanding porous membranes (Fig.…”

Dewetting-induced formation and mechanical properties of synthetic bacterial outer membrane models (GUVs) with controlled inner-leaflet lipid composition

“…Other methods such as gentle hydration, 38 micropipette jetting, 39,40 and GUV budding assisted by swelling hydrogel films [41][42][43] have been used to build GUVs. Gentle hydration involves the simple rehydration of lipid films with an aqueous solution; however, vesicles formed using this method may display undesirable defects such as vesicles within vesicles and/or lipid aggregates on bilayer leaflets that may hinder their utilization.…”

Experimental platform for the functional investigation of membrane proteins in giant unilamellar vesicles

“…57 Overall, PVA assisted GUV formation in the presence of salt tended to decrease the concentration of vesicles, and is in agreement with other reports for polymer assisted swelling methods with increasing ionic strength or osmolarity of solution, 51,65 although few polymer substrates showed increasing GUV concentrations. 66 Thus, concentration of GUVs in the presence of salt might depend on the substrate which is used. Only slight decrease in vesicle concentration was observed in Pt-wire electroformation experiments, mostly due to an increase in vesicle diameter, as was previously observed for electroformation using up to 100 mM NaCl.…”