Naslov
Study liposome adhesion at electrified liquid interface

Autori
Ivošević DeNardis, Nadica

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
3rd ECHEMS Meeting Electrochemistry in Nanosystems and Molecules at Work : Book of Abstracts / Ludvik, J. - Prag, 2007

Skup
ECHEMS Meeting Electrochemistry in Nanosystems and Molecules at Work (3 ; 2007)

Mjesto i datum
Třešť, Češka Republika, 28.06.2007. - 01.07.2007

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
liposome adhesion; electrified interface; mercury electrode

Sažetak
Amperometry at the dropping mercury electrode(DME) is a new analytical method to study liposome adhesion at aqueous interfaces. DME serves as the adhesion sensor (1-3) where the electrical double-layer structure, surface charge density and interfacial tension can be precisely controlled by the applied potential. Liposomes were prepared by thin-film hydration method from Egg lecithin /cholesterol/diacetylphosphate in the molar ratio 7:5:1 (4). The electrical signals of liposomes (diameter 1-100  m) are well-defined current transients of ms duration and amplitudes in the range from +13 to – 11.5  A. At a given potential, amplitude of a signal reflects the liposome size, while the signal frequency depends on liposome concentration. The flow of current is caused by double-layer charge displacement at the mercury/aqueous electrolyte interface due to adhesion and spreading of a single liposome. Adhesion is confined to a broad potential range of positively and negatively charged electrode/aqueous electrolyte interface (from +15.6 to – 11.5  C/cm2 in PBS). Generally, effects of electrostatic interaction of particle fixed charges with the electrode double layer could be detected near the EPZC (3). Thus, surface charge density of a living algal cells could be determined by scanning electrical potential around EPZC to a point of no net current flow, where the charge density of the cell compensates the electrode charge density (3). The potential of no net current flow around EPZC could not be detected in liposome suspensions. Instead, in the range of σ Hg from -1.1 to -4.6 µ ; ; C/cm2 complex adhesion signals appear. These signals reveal a predominance of specific electrostatic interactions of liposome polar heads in a close molecular contact with the mercury electrode, that are not screened by counter ions (5). An intimate contact of phospholipids polar groups with the electrode surface over a broad range of charge densities is also supported by the model of phospholipid bilayer at a gold electrode (6). (1) Žutić, V. ; Kovač, S. ; Tomaić, J. ; Svetličić, V.J. Electroanal. Chem. 1993, 349, 173 (2) Svetličić, V. ; Ivošević, N. ; Kovač, S. ; Žutić, V. Langmuir 2000, 16, 8217 (3) Svetličić, V. ; Hozić, A. ; Electrophoresis 2002, 23, 2080 (4) Gregoriadis, G. Methods Enzymol. 1976, 44, 218 (5) Žutić, V. ; Svetličić, V. ; Hozić Zimmermann, A. ; Ivošević DeNardis, N. ; . Frkanec, R. ; Langmuir 2007, (in press) (6) Burgess, I. ; Li, M. ; Horswell, S. L. ; Szymanski, G. ; Lipkowski, J. ; Majewski, J. ; Satija, S. Biophys. J. 2004, 86, 1763

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Kemija

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