Spatial Organization of Biological Fuctions | BPS Thematic Meeting

Spatial Organization of Biological Functions Meeting

Poster Abstracts

13-POS Board 13 CHARACTERIZATION OF SHORT-LIVED NANOPORE DURING THE ELECTRICAL BREAKDOWN OF THE LIPID BILAYER MEMBRANE Km Mamata Patel 1 ; Saurabh Chaubey 1 ; Dr Prabhat Tripathi 1 ; 1 IIT (BHU), VARANASI, UP INDIA, Department of Chemistry, VARANASI, India We have studied the short-lived pore formation and rupture behaviour in the lipid bilayer membrane for four varieties of phospholipids- DPhPC, POPC, DOPC and DOPG, each differing in their hydrophobic tail and hydrophilic head group. In a typical experiment, we have used the Montal-Muller method to form a perpendicular lipid bilayer membrane on a 100 micrometer Teflon aperture and applied a linear stepwise voltage ranging from 0 to 1 V with a 10 mV voltage step with a 20 milliseconds step duration, while monitoring the ionic-current with picoampere current and microsecond time resolution in 1M KCl buffer solution. We found that the measured distribution of membrane breakdown voltage V breakdown follows the Weibull distribution, and its shape changes with the identity of the lipid molecule. The bimodal Weibull distribution for DPhPC and DOPG suggest that at least two distinct mechanisms are involved in the membrane rupture. Our analysis of the observed short-lived pores both during and prior to the membrane rupture suggests that the pores during the instantaneous rupture at breakdown voltage and the pores prior to the rupture occur independently. The rate of conductance change during pore opening and closing is found to be slower than the rate of conductance change during rupture of lipid bilayer membrane. For DOPG lipid-bilayer, we observed a roughly 5-10 times faster rate of conductance change in comparison to the three lipids, which is likely due to the presence of a negatively charged glycerol group destabilizing the metastable pore during the rupture process. Thus, we suggest that the zwitterionic head group in DPhPC, POPC, and DOPC stabilizes the metastable pore during the rupture via dipole dipole interaction.

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