Ability of sodium dodecyl sulfate to transiently stabilize a phospholipid molecular layer

Nakata, Satoshi; Deguchi, Ayano; Seki, Yota; Fukuhara, Koichi; Goto, Makiko; Denda, Mitsuhiro

doi:10.1016/j.tsf.2016.07.008

Cited by 6 publications

(6 citation statements)

References 25 publications

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“…33 The surface pressure-area isotherms contain no sharp transitions like those expected in the case of a compression-induced transition from the liquid expanded to the liquid condensed phase, proving that all three types of monolayers remained in the liquid expanded phase during compression to the point of buckling. These measured isotherms and collapse pressure values (Table S2, supplementary material) are in good agreement with previous reports, 21,[34][35][36] and they highlight differences in the average area occupied per lipid at a given surface pressure. Specifically, a single DPhPC molecule takes up a larger area (63.9 Å 2 ) compared to both DOPC (53.6 Å 2 ) and POPC (50.3 Å 2 ) at their respective collapse pressures (i.e., maximum pressure before monolayer buckling).…”

Section: Compression Isotherm Measurementssupporting

confidence: 91%

“…1(a)]. However, we and others 21,22 have observed that some types of lipids, including unsaturated lipids such as DOPC and POPC, fail to form well-packed monolayers capable of yielding a stable bilayer-i.e., droplets placed in contact coalesce [ Fig. 1(b)] rather than form an interfacial bilayer.…”

Section: Improved Dib Formation With Evaporation-induced Monolayer Comentioning

confidence: 91%

“…To improve DIB formation with DOPC, other groups have recently shown that amphiphilic compounds (such as SDS and SPAN) used as co-surfactants with lipids promote sufficient monolayer formation and enable the assembly of stable DOPC DIBs even with large droplets. [20][21][22] These findings were explained in the context of lipid-shape factor; addition of cosurfactants with a conical shape that compliments the inverted conical shape of DOPC enables tighter monolayer packing and a better coverage of the oil-water interface. However, the presence of surface active polymers in a lipid-based monolayer or bilayer is known to alter the transport properties of the membrane and, more importantly, may not accurately mimic the membranes of living cells.…”

Section: Introductionmentioning

confidence: 99%

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Evaporation-induced monolayer compression improves droplet interface bilayer formation using unsaturated lipids

et al. 2018

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In this article, we report on a new experimental methodology to enable reliable formation of droplet interface bilayer (DIB) model membranes with two types of unsaturated lipids that have proven difficult for creating stable DIBs. Through the implementation of a simple evaporation technique to condition the spontaneously assembled lipid monolayer around each droplet, we increased the success rates of DIB formation for two distinct unsaturated lipids, namely 1,2-dioleoyl--glycero-3-phosphocholine (DOPC) and 1-palmitoyl-2-oleoyl--glycero-3-phosphocholine (POPC), from less than 10% to near 100%. Separately, using a pendant drop tensiometer, we learned that: (a) DOPC and POPC monolayers do not spontaneously assemble into their tightest possible configurations at an oil-water interface, and (b) reducing the surface area of a water droplet coated with a partially packed monolayer leads to a more tightly packed monolayer with an interfacial tension lower than that achieved by spontaneous assembly alone. We also estimated from Langmuir compression isotherms obtained for both lipids that the brief droplet evaporation procedure prior to DIB formation resulted in a 6%-16% reduction in area per lipid for DOPC and POPC, respectively. Finally, the increased success rates of formation for DOPC and POPC DIBs enabled quantitative characterization of unsaturated lipid membrane properties including electrical resistance, rupture potential, and specific capacitance.

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Section: Compression Isotherm Measurementssupporting

confidence: 91%

Section: Improved Dib Formation With Evaporation-induced Monolayer Comentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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Evaporation-induced monolayer compression improves droplet interface bilayer formation using unsaturated lipids

et al. 2018

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“…Basic understanding on structure of phospholipid monolayer, employing sum-frequency generation spectroscopy, has been reported. , The molecular interaction of the lipid monolayer with various biologically active molecules has a significant effect on biophysical and structural properties of lipid monolayers. In this regard, surfactants, − amino acids (particularly, phenylalanine , ), various drugs, , carbon-based particles, − and ions , are being investigated by many researchers. The importance of such studies particularly between charged surfactants and lipids cannot be over emphasized because of their relevance to biological models, packaging material for DNA/RNA-based drug delivery,− and atmospheric aerosols .…”

Section: Introductionmentioning

confidence: 99%

Interaction of Sodium Dodecyl Sulfate with Lipid Monolayer Studied by Sum-Frequency Generation Spectroscopy at Air–Water Interface

et al. 2017

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We employed vibrational sum-frequency generation (VSFG) spectroscopy to obtain molecular-level understanding of interaction of anionic surfactant sodium dodecyl sulfate (SDS), in low bulk concentration at the micromolar level, with lipid monolayer zwitterionic 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) at the air–water interface. These results are different from those reported at higher bulk concentration of SDS at millimolar level. At very low concentration neither DPPC nor SDS produces any VSFG signal in the CH stretch region in the water subphase, but with the same concentration DPPC produces typical VSFG spectra at the SDS subphase due to interaction between these two molecules. The interaction leads to polar ordering of DPPC molecules with enhancement of VSFG intensity in the CH vibrational region of the hydrophobic tails. The interaction between the lipid and SDS molecules is influenced by concentrations of both lipid and SDS. Hydrophobic interactions between long alkyl chains of SDS and DPPC are responsible for an increase in the conformational order of the alkyl chain of DPPC with a decrease in the gauche defect and increase in trans conformer. Similarly, the orientation and concentration of interfacial water molecules of DPPC monolayer at SDS subphase are controlled by concentration of both SDS and DPPC. The VSFG results are complemented by the surface-pressure measurements.

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“…Since various biologically active molecules affect significantly the structural and biophysical properties of lipid monolayers, their interactions with monolayers are interesting topic of investigation. Several research groups have studied effects of surfactants, − phenylalanine, , drugs, , and other chemicals , on lipid monolayers. Since molecular interactions have weak strengths and long-range characters, their determination is challenging, and hence these studies are pursued both experimentally and theoretically.…”

Section: Introductionmentioning

confidence: 99%

Interaction of l-Phenylalanine with Lipid Monolayers at Air–Water Interface at Different pHs: Sum-Frequency Generation Spectroscopy and Surface Pressure Studies

et al. 2018

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We employed vibrational sum-frequency generation (VSFG) spectroscopy to obtain molecular level understanding of interaction of L-phenylalanine (Phe) with lipid monolayers of zwitterionic 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) at the air−water interface. The measured VSFG spectra in the CH stretch region due to the lipid and Phe, and the OH stretch region due to interfacial water molecules were analyzed. These results in combination with surface pressure studies reveal that the Phe molecules at acidic pH of 5.6 intercalate into DPPC monolayers, and replace some interfacial water molecules. Consequently, there is a decrease in the VSFG intensity in the OH stretch region in the Phe subphase, and a concomitant increase in the surface pressure of the DPPC monolayer. The exclusion of the water molecules is controlled by both the bulk concentration of Phe, and the surface concentration of DPPC. In contrast, at the neutral pH of 7.3 there is an increase in the VSFG intensity due to the interfacial water molecules in the Phe subphase, and a decrease in the surface pressure of the DPPC monolayer. A decrease in the surface pressure, implying an increase in the surface tension toward values of pure water, suggests condensation of lipids to some extent and exposing water regions in the surface. At the neutral pH, the Phe molecules interact mostly with the headgroup of the lipid monolayer without affecting directly the hydrophobic interaction with the tail region. At both the pHs, the microscopic order of the hydrocarbon chains of the DPPC molecules is observed to increase with increased VSFG intensity due to the terminal CH 3 group, and decreased intensity due to the CH 2 group. The interaction of DPPC monolayer with Phe is compared to that with sodium dodecyl sulfate (SDS), and the hydrophobic interactions between the side chains in the latter are found to be relatively much stronger.

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Ability of sodium dodecyl sulfate to transiently stabilize a phospholipid molecular layer

Cited by 6 publications

References 25 publications

Evaporation-induced monolayer compression improves droplet interface bilayer formation using unsaturated lipids

Evaporation-induced monolayer compression improves droplet interface bilayer formation using unsaturated lipids

Interaction of Sodium Dodecyl Sulfate with Lipid Monolayer Studied by Sum-Frequency Generation Spectroscopy at Air–Water Interface

Interaction of l-Phenylalanine with Lipid Monolayers at Air–Water Interface at Different pHs: Sum-Frequency Generation Spectroscopy and Surface Pressure Studies

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