Liposome Behavior in Capillary Electrophoresis

Roberts, Matthew; Locascio-Brown, Laurie; MacCrehan, William A.; Durst, Richard A.

doi:10.1021/ac9603284

Cited by 76 publications

(74 citation statements)

References 24 publications

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“…due to the changing EOF. In most cases, liposomes consisting of POPC, PE and Ch have negative charge, although they consist of either zwitterionic (POPC, PE) or uncharged (Ch) constituents [1,2,6,41]. The present liposomes possess additional negative charges from the phosphate group of DSPE-PEG.…”

Section: Peg-grafted Liposomesmentioning

confidence: 98%

Capillary electrophoresis of liposomes functionalized for protein binding

et al. 2006

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CE enabled assessing the attachment of hexa-histidine-tagged proteins to functionalized phospholipid liposomes. The liposomes were made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, phosphatidyl-ethanolamine, cholesterol and distearoyl-glycero-3-phosphoethanolamine-N-methoxy(polyethylene glycol) in a molar ratio of 29:26:40:5. The unilamellar vesicles, which had an average diameter of 170 nm, were labelled by inclusion of FITC-dextran for fluorescence detection. CE was carried out in poly(vinyl alcohol) (PVA)-coated capillaries at 25 degrees C with a BGE consisting of Tris-HCl (50 mM, pH 8.0). For conjugation of the liposomes with the proteins (soluble synthetic receptor fragments with molecular mass of 60 and 70 kDa, respectively), Ni(2+) was implanted into the vesicle surface by an anchor lipid containing a nitrilotriacetate acid (NTA) group as complexation agent for the metal ions. The difference in surface charge enabled the separation of the different species of interest by CE: plain vesicles, vesicles functionalised with Ni-NTA, vesicle-protein complexes and the species formed upon removal of the Ni-ions by complexation with EDTA. Loss of the Ni-ions resulted in the release of the proteins and the reappearance of the plain Ni-free NTA-liposome species in the electropherograms.

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Section: Peg-grafted Liposomesmentioning

confidence: 98%

Capillary electrophoresis of liposomes functionalized for protein binding

et al. 2006

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“…phospholipid vesicles) are utilized in many LC and CE techniques, either as coatings or (drug) carriers [1][2][3][4]. Lipid aggregates (liposomes, micelles, bicelles, and discoidal micelles) have been used as models of the structure and function of mammalian cell membranes, for instance, in drug partitioning studies [5].…”

Section: Introductionmentioning

confidence: 99%

Dynamic coating of SU‐8 microfluidic chips with phospholipid disks

et al. 2010

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In this work, PEG-stabilized phosphatidylcholine lipid aggregates (disks), mimicking mammalian cell membranes, were introduced as a new biofouling resistant coating for SU-8 polymer microchannels. A rapid and simple method was developed for immobilization of PEGylated phosphatidylcholine disks in microchannels. Microfluidic chips made from SU-8, PDMS, or glass were dynamically coated with the PEGylated disks followed by characterization of their surface chemistry before and after coating. On the basis of the observed changes in EOF and nonspecific protein adsorption, the affinity of the PEGylated disks was shown to be particularly strong toward SU-8. The PEG-lipid coating enabled permanent change in EOF in SU-8 microchannels with an initial value of 4.5 x 10(-8) m(2) V(-1) s(-1), decreasing to 2.1 x 10(-8) m(2) V(-1) s(-1) (immediately after modification), and, eventually, to 1.5 x 10(-8) m(2) V(-1) s(-1) (7 days after modification) for 9 mM sodium borate (pH 10.5) as BGE. As determined by the Wilhelmy plate measurements and microchip-CE analysis of BSA, the PEG-lipid coating also enabled efficient biofouling shield against protein adsorption, similar to that of low amounts of SDS (3.5 mM) or Tween-20 (80 microM) as buffer additives. These results suggest that dynamically attached PEG-lipid aggregates provide stable, biomimicking surface modification that efficiently reduces biofouling on SU-8.

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“…More recently than most of the alternatives to SDS micelles noted above, vesicles formed from phospholipids [43,44] or surfactants [45] were introduced as a PSP for EKC. Compared to micelles, vesicles are much larger aggregates of phospholipid or synthetic surfactant molecules consisting of one or more concentric spherical bilayers ("unilamellar" or "multilamellar") surrounding an internal cavity of solvent.…”

Section: Introductionmentioning

confidence: 99%

Compositional effects on electrophoretic and chromatographic figures of merit in electrokinetic chromatography with cetyltrimethylammonium bromide/sodium octyl sulfate vesicles as the pseudostationary phase. Part 1: Effect of the phase ratio

et al. 2008

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The effect of the phase ratio on the electrophoretic and chromatographic properties of unilamellar vesicles comprised of cetyltrimethylammonium bromide (CTAB) and sodium octyl sulfate (SOS) was investigated in EKC. The surfactant concentration of the vesicles was 0.9, 1.2, 1.5, and 1.8% w/v, with a mole ratio of 1:3.66 (CTAB/SOS). Results were compared to those obtained using SDS micelles at concentrations of 1.0% (w/v, 35 mM) and 1.5% (52 mM). The CTAB/SOS vesicles (0.9-1.8% w/v) provided a significantly larger elution range (5.7 < or = t(ves)/t(0) < or = 8.7) and greater hydrophobic (methylene) selectivity (2.8 < or = alpha(CH2) < or = 3.1) than SDS micelles (3.1 < or = t(mc)/t(0) < or = 3.3; alpha(CH2) = 2.2). Whereas the larger elution range can be attributed to the 25% reduction in EOF due to the interaction of unaggregated CTAB cations and the negatively charged capillary wall, the higher methylene selectivity is likely due to the lower concentration of water expected in the CTAB/SOS vesicle bilayer compared to the Palisades layer of SDS micelles. For a given phase ratio, CTAB/SOS vesicles are somewhat less retentive than SDS micelles, although retention factors comparable to those observed in 1.0-1.5% SDS can be obtained with 1.5-1.8% CTAB/SOS. A linear relationship was observed between phase ratio and retention factor, confirming the validity of the phase ratio model for these vesicles. Unique polar group selectivities and positional isomer shape selectivities were obtained with CTAB/SOS vesicles, with both types of selectivities being nearly independent of the phase ratio. For four sets of positional isomers, the elution order was always para < ortho < meta. Finally, the thermodynamics of solute retention was qualitatively similar to that reported for other surfactant aggregates (micelles and microemulsions); the enthalpic contribution to retention was consistently favorable for all compounds, whereas the entropic contribution was favorable only to hydrophobic solutes.

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Liposome Behavior in Capillary Electrophoresis

Cited by 76 publications

References 24 publications

Capillary electrophoresis of liposomes functionalized for protein binding

Capillary electrophoresis of liposomes functionalized for protein binding

Dynamic coating of SU‐8 microfluidic chips with phospholipid disks

Compositional effects on electrophoretic and chromatographic figures of merit in electrokinetic chromatography with cetyltrimethylammonium bromide/sodium octyl sulfate vesicles as the pseudostationary phase. Part 1: Effect of the phase ratio

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