Dataset Information

Glycosaminoglycan-mediated selective changes in the aggregation states, zeta potentials, and intrinsic stability of liposomes.

ABSTRACT: Though the aggregation of glycosaminoglycans (GAGs) in the presence of liposomes and divalent cations has been previously reported, the effects of different GAG species and minor changes in GAG composition on the aggregates that are formed are yet unknown. If minor changes in GAG composition produce observable changes in the liposome aggregate diameter or zeta potential, such a phenomenon may be used to detect potentially dangerous oversulfated contaminants in heparin. We studied the mechanism of the interactions between heparin and its oversulfated glycosaminoglycan contaminants with liposomes. Herein, we demonstrate that Mg(2+) acts to shield the incoming glycosaminoglycans from the negatively charged phosphate groups of the phospholipids and that changes in the aggregate diameter and zeta potential are a function of the glycosaminoglycan species and concentration as well as the liposome bilayer composition. These observations are supported by TEM studies. We have shown that the organizational states of the liposome bilayers are influenced by the presence of GAG and excess Mg(2+), resulting in a stabilizing effect that increases the T(m) value of DSPC liposomes; the magnitude of this effect is also dependent on the GAG species and concentration present. There is an inverse relationship between the percent change in aggregate diameter and the percent change in aggregate zeta potential as a function of GAG concentration in solution. Finally, we demonstrate that the diameter and zeta potential changes in POPC liposome aggregates in the presence of different oversulfated heparin contaminants at low concentrations allow for an accurate detection of oversulfated chondroitin sulfate at concentrations of as low as 1 mol %.

SUBMITTER: Nyren-Erickson EK

PROVIDER: S-EPMC3502640 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Glycosaminoglycan-mediated selective changes in the aggregation states, zeta potentials, and intrinsic stability of liposomes.

Nyren-Erickson Erin K EK Haldar Manas K MK Totzauer Jessica R JR Ceglowski Riley R Patel Dilipkumar S DS Friesner Daniel L DL Srivastava D K DK Mallik Sanku S

Langmuir : the ACS journal of surfaces and colloids 20121107 46

Though the aggregation of glycosaminoglycans (GAGs) in the presence of liposomes and divalent cations has been previously reported, the effects of different GAG species and minor changes in GAG composition on the aggregates that are formed are yet unknown. If minor changes in GAG composition produce observable changes in the liposome aggregate diameter or zeta potential, such a phenomenon may be used to detect potentially dangerous oversulfated contaminants in heparin. We studied the mechanism o ...[more]

PMID: 23102026

Similar Datasets

Project description:A large number (1253) of high-quality streaming potential coefficient ( Csp) measurements have been carried out on Berea, Boise, Fontainebleau, and Lochaline sandstones (the latter two including both detrital and authigenic overgrowth forms), as a function of pore fluid salinity ( Cf) and rock microstructure. All samples were saturated with fully equilibrated aqueous solutions of NaCl (10 -5 and 4.5 mol/dm 3) upon which accurate measurements of their electrical conductivity and pH were taken. These Csp measurements represent about a fivefold increase in streaming potential data available in the literature, are consistent with the pre-existing 266 measurements, and have lower experimental uncertainties. The Csp measurements follow a pH-sensitive power law behaviour with respect to Cf at medium salinities ( Csp=-1.44×10-9Cf-1.127 , units: V/Pa and mol/dm 3) and show the effect of rock microstructure on the low salinity Csp clearly, producing a smaller decrease in Csp per decade reduction in Cf for samples with (i) lower porosity, (ii) larger cementation exponents, (iii) smaller grain sizes (and hence pore and pore throat sizes), and (iv) larger surface conduction. The Csp measurements include 313 made at Cf>1 mol/dm 3 , which confirm the limiting high salinity Csp behaviour noted by Vinogradov et al., which has been ascribed to the attainment of maximum charge density in the electrical double layer occurring when the Debye length approximates to the size of the hydrated metal ion. The zeta potential ( ? ) was calculated from each Csp measurement. It was found that ? is highly sensitive to pH but not sensitive to rock microstructure. It exhibits a pH-dependent logarithmic behaviour with respect to Cf at low to medium salinities ( ?=0.01133log10Cf+0.003505 , units: V and mol/dm 3) and a limiting zeta potential (zeta potential offset) at high salinities of ?o=-17.36±5.11 mV in the pH range 6-8, which is also pH dependent. The sensitivity of both Csp and ? to pH and of Csp to rock microstructure indicates that Csp and ? measurements can only be interpreted together with accurate and equilibrated measurements of pore fluid conductivity and pH and supporting microstructural and surface conduction measurements for each sample.

Dataset Information

Glycosaminoglycan-mediated selective changes in the aggregation states, zeta potentials, and intrinsic stability of liposomes.

Publications

Glycosaminoglycan-mediated selective changes in the aggregation states, zeta potentials, and intrinsic stability of liposomes.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure