Analytical ultracentrifugation of colloids

Planken, Karel L.; Cölfen, Helmut

doi:10.1039/c0nr00215a

Cited by 157 publications

(167 citation statements)

References 103 publications

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“…In contrast, Analytical ultracentrifugation (AUC) involves the sedimentation of particles at high rotational speeds in a sample cell; this leads to fractionation of the nanocomposite particles in situ and hence enables assessment of their density distribution. 49,50 AUC has been widely applied for the analysis of colloidal particles 49 including the study of polyelectrolyte complexes, 51 latexes, 52,53 inorganic sols 52,[54][55][56] or hybrid particles. 50,52,57 In the present study, AUC is utilized to examine the hypothesis that core-shell polystyrene/silica particles of finite polydispersity are expected to exhibit a density distribution.…”

Section: Resultsmentioning

confidence: 99%

Correcting for a Density Distribution: Particle Size Analysis of Core–Shell Nanocomposite Particles Using Disk Centrifuge Photosedimentometry

et al. 2012

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Abstract. Many types of colloidal particles possess a core-shell morphology. In this paper we show that, if the core and shell densities differ, this morphology leads to an inherent density distribution for particles of finite polydispersity. If the shell is denser than the core, this density distribution implies an artificial narrowing of the particle size distribution as determined by disk centrifuge photosedimentometry (DCP). In the specific case of polystyrene/silica nanocomposite particles, which consist of a polystyrene core coated with a monolayer shell of silica nanoparticles, we demonstrate that the particle density distribution can be determined by analytical ultracentrifugation and introduce a mathematical method to account for this density distribution by reanalyzing the raw DCP data. Using the mean silica packing density calculated from small-angle xray scattering, the real particle density can be calculated for each data point. The corrected DCP particle size distribution is both broader and more consistent with particle size distributions reported for the same polystyrene/silica nanocomposite sample using other sizing techniques, such as electron microscopy, laser light diffraction and dynamic light scattering. Artifactual narrowing of the size distribution is also likely to occur for many other polymer/inorganic nanocomposite particles comprising a low-density core of variable dimensions coated with a high-density shell of constant thickness, or for core-shell latexes where the shell is continuous rather than particulate in nature.

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Section: Resultsmentioning

confidence: 99%

Correcting for a Density Distribution: Particle Size Analysis of Core–Shell Nanocomposite Particles Using Disk Centrifuge Photosedimentometry

et al. 2012

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“…For spheres of uniform composition, the particle density can be calculated from the properties of the fluid (viscosity η and mass density ρ) and the particle velocity (v) for measurements performed in unlabeled and deuterium-labeled solvents [92]. This simple approach, however, is not strictly appropriate for the concentric spheres used in this study.…”

Section: Nm Diameter Latexesmentioning

confidence: 99%

“…Analytical centrifugation is a method that can be used to study the particles; it is a well-known way to study the size and density of colloids [92]. However, the approach has predominantly been employed in water, due to application in the study of biomolecules [93,94].…”

Section: Nm Diameter Latexesmentioning

confidence: 99%

The internal structure of poly(methyl methacrylate) latexes in nonpolar solvents

Smith

Finlayson

Gillespie

et al. 2016

Journal of Colloid and Interface Science

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“…Initially, techniques were optimised at environmentally high concentrations (2-100 mg L À1 ) in order to use the available on-line detectors (static (SLS) and dynamic light scattering (DLS)), which provide direct information on the radii of gyration (R g ) and the hydrodynamic radii (R h ) of the ENPs. Once the experimental parameters were well defined for the elution, off-line detection of HDC fractions were realised using DLS, analytical ultracentrifugation (AUC [15][16][17] ) and single particle inductively coupled plasma mass spectrometry (SP-ICP-MS [18,19] ) at lower ENP concentrations (200 mg L À1 to 3 mg L À1 for DLS and AUC and 0.1-2.0 mg L À1 for SP-ICP-MS). Finally, the direct coupling of the HDC column to SP-ICP-MS allowed the direct detection and characterisation of a nanosilver particle that was spiked into a river water sample at the environmentally relevant concentration of 4 mg L…”

Section: Introductionmentioning

confidence: 99%

Separation, detection and characterisation of engineered nanoparticles in natural waters using hydrodynamic chromatography and multi-method detection (light scattering, analytical ultracentrifugation and single particle ICP-MS)

Proulx

Wilkinson

2014

Environ. Chem.

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Environmental context. The effects of engineered nanoparticles on the environment and on human health are difficult to evaluate largely because nanoparticles are so difficult to measure. The main problems are that concentrations are low and the engineered nanoparticles are often difficult to distinguish from the environmental matrices in which they are found. We report a separation technique that facilitates the detection of engineered nanoparticles in natural waters.Abstract. Few analytical techniques are presently able to detect and quantify engineered nanoparticles (ENPs) in the environment. The major challenges result from the complex matrices of environmental samples and the low concentrations at which the ENPs are expected to be found. Separation techniques such as asymmetric flow field flow fractionation (AF4) and more recently, hydrodynamic chromatography (HDC) have been used to partly resolve ENPs from their complex environmental matrices. In this paper, HDC was first coupled to light scattering detectors in order to develop a method that would allow the separation and detection of ENPs spiked into a natural water. Size fractionated samples were characterised using off-line detectors including analytical ultracentrifugation (AUC), dynamic light scattering (DLS) and single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). HDC was able to separate a complex mixture of polystyrene, silver and gold nanoparticles (radii of 60, 40, 20 and 10 nm) contained within a river water matrix. Furthermore, the feasibility of using HDC coupled to SP-ICP-MS was demonstrated by detecting 4 mg L À1 of a 20-nm (radius) nAg in a river water sample.

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Analytical ultracentrifugation of colloids

Cited by 157 publications

References 103 publications

Correcting for a Density Distribution: Particle Size Analysis of Core–Shell Nanocomposite Particles Using Disk Centrifuge Photosedimentometry

Correcting for a Density Distribution: Particle Size Analysis of Core–Shell Nanocomposite Particles Using Disk Centrifuge Photosedimentometry

The internal structure of poly(methyl methacrylate) latexes in nonpolar solvents

Separation, detection and characterisation of engineered nanoparticles in natural waters using hydrodynamic chromatography and multi-method detection (light scattering, analytical ultracentrifugation and single particle ICP-MS)

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