Preparing giant unilamellar vesicles (GUVs) of complex lipid mixtures on demand: Mixing small unilamellar vesicles of compositionally heterogeneous mixtures

Tripta Bhatia, Peter Husen, Jonathan Brewer, Luis A. Bagatolli, Per L. Hansen, John H. Ipsen, Ole G. Mouritsen
Biochimica et Biophysica Acta (BBA) - Biomembranes
1848
3175 - 3180
2015
abstract
Abstract Giant unilamellar vesicles (GUVs) are simple model membrane systems of cell-size, which are instrumentalto study the function of more complex biological membranes involving heterogeneities in lipid composition, shape, mechanical
properties, and chemical properties. We have devised a method that makes it possible to prepare a uniform sample of ternary
GUVs of a prescribed composition and heterogeneity by mixing different populations of small unilamellar vesicles (SUVs). The validity\øf the protocol has been demonstrated by applying it to ternary lipid mixture of DOPC, DPPC, and cholesterol by mixing small unilamellar
vesicles (SUVs) of two different populations and with different lipid compositions. The compositional homogeneity among GUVs resulting
from SUV mixing is quantified by measuring the area fraction of the liquid ordered-liquid disordered phases in giant vesicles and is
found to be comparable to that in GUVs of the prescribed composition produced from hydration of dried lipids mixed in organic solvent.
Our method opens up the possibility to quickly increase and manipulate the complexity of GUV membranes in a controlled manner at physiological
buffer and temperature conditions. The new protocol will permit quantitative biophysical studies of a whole new class of well-defined model
membrane systems of a complexity that resembles biological membranes with rafts.