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Phase Change in Membranes Observed by Variations in Electrical Capacitance
Author(s) -
Doermann Alex,
Goggins Landon,
Larsen David,
Woodbury Dixon J
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.1066.6
Subject(s) - membrane , capacitance , differential scanning calorimetry , phase transition , phase (matter) , biological membrane , exocytosis , chemistry , lipid bilayer , differential capacitance , lipid bilayer phase behavior , materials science , analytical chemistry (journal) , model lipid bilayer , membrane fluidity , biophysics , chemical physics , thermodynamics , chromatography , biochemistry , biology , physics , organic chemistry , electrode
Lipid membranes made of DPPC (Dipalmitoyl‐phosphatidyl‐choline) are well‐documented to undergo phase changes across specific critical temperatures. Here, it is shown that the electrical capacitance of a planar lipid membrane changes dramatically as the membrane changes phase. By cooling a DPPC membrane below the transition temperature, T m (41.5°C), the capacitance increases >20%. Since capacitance is directly related to surface area and inversely related to membrane thickness, these data provide insight to the fundamental structures of the different phases. Although these phase changes have been measured before using X‐ray, DSC (Differential Scanning Calorimetry), and AFM (Atomic Force Microscopy), these previous studies mostly observed stacked or supported membranes; the present study demonstrates the phase change in a single, fully hydrated membrane. Hence, this method provides the opportunity to measure directly, in a biologically relevant system, the effects that such a change in membrane properties have on membrane proteins and the process of exocytosis.