Quantitative Assessment of the Conditioning of the Inversion of Quasi-Elastic and Static Light Scattering Data for Particle Size Distributions

Vos, Chris De; Deriemaeker, and Luc; Finsy, Robert

doi:10.1021/la950852q

Cited by 50 publications

(28 citation statements)

References 13 publications

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“…Decay times are used to determine the distribution of the diffusion coefficients D of the particles, which in turn can be converted in a distribution of apparent hydrodynamic radii, R H , using the Stokes-Einstein relationship R H = k B T/6 ÁD, where k B T is the thermal energy and Á the solvent viscosity. The values of the radii shown here correspond to the average values on several measurements and are obtained from intensity weighted distributions [45,46].…”

Section: Dynamic Light Scattering Measurementsmentioning

confidence: 84%

Salt-induced reentrant stability of polyion-decorated particles with tunable surface charge density

Sennato

Carlini

Truzzolillo

et al. 2016

Colloids and Surfaces B: Biointerfaces

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The electrostatic complexation between DOTAP/DOPC unilamellar liposomes and an oppositely charged polyelectrolyte (NaPA) has been investigated in a wide range of the liposome surface charge density. We systematically characterized the reentrant condensation and the charge inversion of polyelectrolyte-decorated liposomes by means of dynamic light scattering and electrophoresis. We explored the stability of this model polyelectrolyte/colloid system at different values of the surface charge of the bare liposomes and by changing two independent control parameters of the suspensions: the polyelectrolyte/colloid charge ratio and the ionic strength of the aqueous suspending medium. The progressive addition of neutral DOPC lipid within the liposome membrane gave rise to an interesting phenomenon which has not been observed previously: the stability diagram of the suspensions showed a novel reentrance due to the crossing of the desorption threshold of the polyelectrolyte. Indeed, at fixed charge density of the bare DOTAP/DOPC liposomes and for a wide range of polyion concentrations, we showed that the simple electrolyte addition first (low salt regime) destabilizes the suspensions because of the enhanced screening of the residual repulsion between the complexes, and then (high salt regime) determines the onset of a new stable phase, originated by the absence of polyelectrolyte adsorption on the particle surfaces. We show that the observed phenomenology can be rationalized within the modified Velegol-Thwar model for heterogeneously charged particles and that the polyelectrolyte desorption fits well the predictions of the adsorption theory of Winkler and Cherstvy [1]. Our findings unambiguously support the picture of the reentrant condensation as driven by the correlated adsorption of the polyelectrolyte chains on the particle surface, providing interesting insights into possible mechanisms for tailoring complex colloids via salt-induced effects.

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Section: Dynamic Light Scattering Measurementsmentioning

confidence: 84%

Salt-induced reentrant stability of polyion-decorated particles with tunable surface charge density

Sennato

Carlini

Truzzolillo

et al. 2016

Colloids and Surfaces B: Biointerfaces

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show abstract

“…Decay times are used to determine the distribution of the diffusion coefficients D0 of the particles, which in turn can be converted in a distribution of apparent hydrodynamic diameter, Dh, using the Stokes-Einstein relationship Dh = kBT/3D0, where kB is the Boltzmann constant, T the absolute temperature and  the solvent viscosity (Berne and Pecora, 1976). The values of the radii shown in this work correspond to the average values on several measurements and are obtained from intensity weighted distributions (Provencher, 1982;De Vos, Deriemaeker and Finsy, 1996). The thermal protocol used for both OMVs, MVs and bacteria in DLS measurements consists of an ascending ramp from 10°C to 45°C with temperature step of 1°C.…”

Section: Dls and Turbidimetric Measurements Were Performed Employing mentioning

confidence: 99%

Biophysical Characterization of Membrane Phase Transition Profiles for the Discrimination of Outer Membrane Vesicles (OMVs) From Escherichia coli Grown at Different Temperatures

et al. 2020

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Dynamic Light Scattering (DLS), Small Angle X-ray Scattering (SAXS) and Transmission Electron Microscopy (TEM) are physical techniques widely employed to characterize the morphology and the structure of vesicles such as liposomes or human extracellular vesicles (exosomes). Bacterial extracellular vesicles are similar in size to human exosomes, although their function and membrane properties have not been elucidated in such detail as in the case of exosomes. Here, we applied the above cited techniques, in synergy with the thermodynamic characterization of the vesicles lipid membrane using a turbidimetric technique to the study of vesicles produced by Gram-negative bacteria (Outer Membrane Vesicles, OMVs) grown at different temperatures. This study demonstrated that our combined approach is useful to discriminate vesicles of different origin or coming from bacteria cultured under different experimental conditions. We envisage that in a near future the techniques employed in our work will be further implemented to discriminate complex mixtures of bacterial vesicles, thus showing great promises for biomedical or diagnostic applications.

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“…Note that intensity should be the less affected by the "degree of ill-conditioning" in the inversion of the Laplace transform of measured data. 48 T 1A for HC, PH, and PEG exhibited low probability (in the case of PEG 5000 , it was almost zero), and the tendency followed was T 1A HC ∼ T 1A PH < T 1A PEG . T 1B for PEG and for the lipidic regions HC and PH is the most populated of both T 1 for these molecular regions, behaves as a common proton system, and increases with n, although T 1B PEG seems to grow faster.…”

Section: ■ Conclusionmentioning

confidence: 96%

Water and Membrane Dynamics in Suspensions of Lipid Vesicles Functionalized with Poly(ethylene glycol)s

2014

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The present work was aimed at studying the molecular dynamics at different levels of model membranes having a simulated glycoclix, with focus on the molecular crowding conditions at the lipid-water interfacial region. Thus, binary mixtures of dipalmitoylphosphatidylcholine (dpPC) and a poly(ethylene glycol) (PEG(n)) derivative of dipalmitoylphosphatidylethanolamine (PE) (where n = 350, 1000, and 5000, respectively, refer to PEG molecular masses) were submitted to (1)H spin-lattice relaxation time (T1) and (31)P NMR spectra analysis. (1)H NMR relaxation times revealed two contributing components in each proton system (PEG, phospholipids, and water), for all the mixtures studied, exhibiting values of T1 with very different orders of magnitude. This allowed identifying confined and bulk water populations as well as PEG moieties becoming more disordered and independent from the phospholipid moiety as n increased. (31)P spectra showed a typical broad bilayer signal for n = 350 and 1000, and an isotropic signal characteristic of micelles for n = 5000. Surface pressure (π)-molecular area isotherms and compressional modulus measurements provided further structural information. Moreover, epifluorescence microscopy data from monolayers at π ∼ 30 mN/m, the expected equilibrium π in lipid bilayers, allowed us to postulate that both (1)H populations resolved through NMR in phospholipids and lipopolymers corresponded to different phase domains.

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Quantitative Assessment of the Conditioning of the Inversion of Quasi-Elastic and Static Light Scattering Data for Particle Size Distributions

Cited by 50 publications

References 13 publications

Salt-induced reentrant stability of polyion-decorated particles with tunable surface charge density

Salt-induced reentrant stability of polyion-decorated particles with tunable surface charge density

Biophysical Characterization of Membrane Phase Transition Profiles for the Discrimination of Outer Membrane Vesicles (OMVs) From Escherichia coli Grown at Different Temperatures

Water and Membrane Dynamics in Suspensions of Lipid Vesicles Functionalized with Poly(ethylene glycol)s

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