Electric Gradient Field Applied to Lipid Monolayers – Niels Bohr Institute - University of Copenhagen

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Electric Gradient Field Applied to Lipid Monolayers

Thesis defense by Asger Tønnesen 

Nerve membranes mainly consist of charged and especially zwitterionic phospholipids with polar head groups. An electrical stimulus of a nerve membrane might then affect such lipids. A suitable zwitterionic phospholipid (DPPC) was investigated by using the 90 year old Langmuir technique for controlling the state of a 2-dimensional lipid monolayer. This was combined with real time observations and imaging of the monolayer achieved with wide field fluorescence microscopy. An electric gradient field applied onto the monolayer of DPPC was observed to locally change the state of the monolayer into a condensed state or into a liquid state with a field of opposite sign.

The observations are supported by calculations of the electric field-dipole interactions appearing in the system. Since the strength of electric field used was in the order of 106V/m one should not doubt that bilayers consisting of zwitterioninc phospholipids are affected by an electric gradient field of equal strength.­­

Supervisor: Thomas Heimburg