AFM Investigations of Phase Separation in Supported Membranes of Binary Mixtures of POPC and an Eicosanyl-Based Bisphosphocholine Bolalipid

作者：Mulligan Kirk; Brownholland David; Carnini Anna; Thompson David H^*; Johnston Linda J

来源：Langmuir, 2010, 26(11): 8525-8533.

DOI：10.1021/la904532s

Supported membranes prepared from binary mixtures of DOPC and the bolalipid C(20)BAS have been examined by atomic force microscopy (A FM). The supported membranes are phase separated to give a thicker DOPC-rich phase and a thinner bolalipid-rich phase for it range of lipid compositions. These results confirm an earlier prediction from mean field theory that phase separation is the thermodynamically stable state for membranes containing approximately equimolar C(20)BAS and double chain monopolar lipids with chain lengths exceeding 15 carbons. Hydrophobic mismatch between the monopolar lipid hydrocarbon chains and the membrane spanning bolalipid chains was suggested to provide the driving force for phase separation. The A FM results also show that the morphology of the mixed POPC:C(20)BAS supported membranes varies significantly with the conditions used to prepare the vesicles and supported membrane samples. The complex membrane morphologies observed are attributed to the interplay of several factors, including a compositionally heterogeneous vesicle population, exchange of lipid between the vesicle solution and solid substrate during formation of the supported membrane, and slow equilibration of domains due to pinning oldie lipids to the solid support.

• 出版日期2010-6-1