Anomalous Solubilization Behavior of Dimyristoylphosphatidyl-choline Liposomes Induced by Sodium Dodecyl Sulfate Micelles

The Mechanism of Vesicle Solubilization by the Detergent Sodium Dodecyl Sulfate

“…The detection of a multi-step solubilization mechanism in LUVs agrees well with optical microscopy and phase contract measurements reported for giant unilamellar vesicles composed of 1-palmitoyl-2-oleoylglycero-3-phosphocholine (POPC) and DMPC lipids and with diameters > 1 m [21,22] . These experiments demonstrated that injection of SDS around the CMC causes an initial increase in the membrane surface area over the first several seconds, attributed to the homogeneous incorporation of SDS into the outer layer, which precedes membrane fracturing, the opening of transient nanopores and the ejection of mixed micelles.…”

“…Additionally, optical microscopy based on the phase contrast and fluorescence imaging of giant unilamellar vesicles also indicate changes in membrane curvature after SDS incorporation, closely followed by the stress-induced formation of macropores and fragmentation [21] . At SDS concentrations lower than the critical micelle concentration (CMC), transmission microscopy experiments also indicate the homogeneous distribution of SDS monomers into the membrane, followed by the gradual formation of mixed micelles and at concentrations around the CMC, local instabilities in the vesicle architecture are introduced across the structure [22] . Unfortunately, these microscopy tools are limited to a spatial resolution of ~250 nm and cannot access the solubilization dynamics of vesicles which are smaller than the optical diffraction limit and which have high radii of curvature.…”

The Mechanism of Vesicle Solubilization by the Detergent Sodium Dodecyl Sulfate

“…The detection of a multistep solubilization mechanism in LUVs agrees well with optical microscopy and phase contrast measurements reported for giant unilamellar vesicles composed of 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) and DMPC lipids and with diameters > 1 μm. 20,21 These experiments demonstrated that injection of SDS around the cmc causes a change in the spontaneous curvature over the first several seconds, attributed to the homogeneous incorporation of SDS into the outer layer, which precedes membrane fracturing, the opening of transient nanopores, and the ejection of mixed micelles. With increasing GUV size, the local density of SDS incorporation was found to differ across the membrane resulting in local instabilities.…”

“…20 At SDS concentrations lower than the critical micelle concentration (cmc), transmission microscopy experiments also indicate the homogeneous distribution of SDS monomers into the membrane, followed by the gradual formation of mixed micelles, and at concentrations around the cmc, local instabilities in the vesicle architecture are introduced across the structure. 21 Unfortunately, these microscopy tools are limited to a spatial resolution of ∼250 nm and cannot access the solubilization dynamics of vesicles which are smaller than the optical diffraction limit and which have high radii of curvature. Moreover, conventional microscopy tools can only measure macroscopic changes in the membrane structure and packing density and provide little structural and mass information on the nanoscale, motivating the need for the multidisciplinary approach outlined here to gain molecular-level insight into this important biological problem.…”

“…Additionally, optical microscopy based on the phase contrast and fluorescence imaging of giant unilamellar vesicles also indicate changes in the membrane curvature after SDS incorporation, closely followed by the stress-induced formation of macropores and fragmentation . At SDS concentrations lower than the critical micelle concentration (cmc), transmission microscopy experiments also indicate the homogeneous distribution of SDS monomers into the membrane, followed by the gradual formation of mixed micelles, and at concentrations around the cmc, local instabilities in the vesicle architecture are introduced across the structure . Unfortunately, these microscopy tools are limited to a spatial resolution of ∼250 nm and cannot access the solubilization dynamics of vesicles which are smaller than the optical diffraction limit and which have high radii of curvature.…”