National Physical Laboratory

Nanomaterials characterisation techniques for powders and liquid dispersions

Nanomaterials characterisation techniques for powders and liquid dispersions: Attribute / Value / Unit table
  • Characterisation of a wide range of micro- and nano-sized materials, including metal, oxide, latex, silica, emulsions, graphene, bubbles, capsules and biological particles
  • Measurement of size, high resolution size distribution, density and surface area using multiple techniques
  • Distribution of size and zeta-potential across a heterogeneous sample
  • Multi-technique approach to nanoparticle characterisation
  • Measurement of production of reactive oxygen species
  • Measurement of mechanical properties of individual particles and capsules
  • Accurate measurement of chemical composition, impurities and thickness of particle coatings
  • Stability of dispersions (sedimentation and agglomeration over time) by turbidity measurement coupled with zeta-potential and other analytical methods

Follow the links in the table below for some examples of nanomaterials characterisation.

Example applications:

  • Protein-functionalised particles for biosensing, drug delivery and lateral flow cytometry
  • Catalysts
  • Metal oxide nanoparticles for cosmetic formulations
  • Graphene and graphite
  • Core, core/shell and core/shell/shell quantum dots for biological labelling and electronics

Instrumentation:

Instrumentation for nanoparticle analysis available at NPL includes: Dynamic Light Scattering (DLS); Electrophoretic Light Scattering (ELS) for zeta-potential; Differential Centrifugal Sedimentation (DCS) / Centrifugal Liquid Sedimentation (CLS); Nanoparticle Tracking Analysis (NTA); Tuneable Resistive Pulse Sensing (TRPS); UV-Visible Spectroscopy; Surface Area; X-ray Photoelectron Spectroscopy (XPS); Secondary Ion Mass Spectroscopy (SIMS); Atomic Force Microscopy (AFM); Electron Microscopy (EM); Fourier Transform Infrared Spectroscopy (FTIR); Raman Spectroscopy; Circular Dichroism (CD).

The table below lists some relevant techniques available at NPL and the type of properties they may be used for. Further information on measurement services provided in the Surface & Nanoanalysis areas is available here

Technique Property
Size Specific Surface Area Size distribution / agglomeration Shape Density Elemental composition Surface chemistry and charge Coating thickness Concentration
Dynamic Light Scattering (DLS)
Differential Centrifugal Sedimentation (DCS)
Particle Tracking Analysis (PTA)

Tunable Resistive Pulse Sensing (TRPS)

Liquid NMR
X-Ray Photoelectron Spectroscopy (XPS)
Scanning Probe Microscopy
Electron Microscopy (SEM, EELS, STEM, FIB and TEM

 

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  • Issues relating to product development and QA
  • Issues relating to process control
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  • Problem solving on measurement issues
  • Demonstrating or assessing measurement systems or product performance

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Customer Service tel: +44 20 8943 8637
E-mail: nanoparticles_enquiries@npl.co.uk


Examples of Nanoparticle Characterisation:

DLS of gold nanoparticles coated with polyethylene glycol (PEG)

Dynamic Light Scattering (DLS) of gold nanoparticles coated with polyethylene glycol (PEG)

Size distribution of 60 nm gold nanoparticles as measured by DLS before (red) and after coating with 2 kDa (blue) or 5 kDa (green) thiol-terminated polyethylene glycol (PEG) molecules. The shift in the peak modes indicate successful functionalisation of the nanoparticles with PEG.

High resolution size distribution of latex nanoparticles for lateral flow applications by DCS

High resolution size distribution of latex nanoparticles for lateral flow applications by DCS

Size distribution of polystyrene nanoparticles before (blue) and after (red) antibody functionalisation measured by DCS. The high resolution of the technique allows to quantify the nanoparticle agglomerations. The main peak shifts due to the formation of a protein corona, whose thickness can be estimated.

Size and density measurements of polystyrene nanoparticles by DCS

Size and density measurements of polystyrene nanoparticles

We can determine both size and density of nanoparticles by performing two DCS distinct measurements by differential centrifugal sedimentation (DCS) using different densities of the solution the nanoparticles move through. In this example, we have used sucrose solutions in water, where the nanoparticles sediment, and deuterium, where the nanoparticles float. Figure A shows the measured size distributions, together with a typical size distribution measured by DLS for comparison. Figure B shows how the size results vary depending on the density assumed for the nanoparticles. The nanoparticles' size and density are found where the two curves intersect. The nanoparticles are NIST polystyrene size standards with nominal size of (100 ± 3) nm. We measure a size of (98 ± 4) nm and a density of 1.053 g/cm3.

PTA of gold nanoparticles coated with IgG antibodies

Particle Tracking Analysis (PTA) of gold nanoparticles coated with IgG antibodies

Size distribution of 40 nm gold nanoparticles as measured by PTA before (blue) and after (red) incubation is a solution containing IgG antibodies. The shift in the peak modes indicate the formation of an antibody layer around the nanoparticles [1].

[1] Quantitation of IgG protein adsorption to gold nanoparticles using particle size measurement, N. C. Bell, C. Minelli and A. G. Shard, Analytical Methods, 2013, DOI: 10.1039/C3AY40771C

Size and Zeta-potential analysis of silica nanoparticles in biological serum by TRPS

Size and Zeta-potential analysis of silica nanoparticles in biological serum by TRPS

Particle-by-particle size and Zeta (ζ-potential distributions of silica nanoparticles in buffer (green) and in serum (red) after 24h incubation, as measured simultaneously by TRPS. In the central graph, every dot relates to a single nanoparticle, whose size and ζ-potential are simultaneously measured. The resulting distributions across the sample are shown in the graphs above and on the right respectively. The shift in the main peak indicates the formation of a 5 nm thick protein corona, which changes the surface charge of the nanoparticles to more positive values [1].

[1] Size and ζ-Potential Measurement of Silica Nanoparticles in Serum Using Tunable Resistive Pulse Sensing, A. Sikora, A. G. Shard, and C. Minelli, Langmuir, 2016, DOI: 10.1021/acs.langmuir.5b04160

XPS chemical analysis of super paramagnetic iron oxide nanoparticles (SPIONs) for medical applications

XPS chemical analysis of super paramagnetic iron oxide nanoparticles (SPIONs) for medical applications

XPS analysis of super paramagnetic iron oxide nanoparticles (SPIONs) before (grey lines) and after (black lines) coating with BSA. The survey spectrum (A) as well as the high resolution spectra relative to the C 1s (B), N 1s (C), O 1s (D), Fe 2p (E) and S 2p (F) regions are shown. To note that nitrogen, only present in BSA, is not visible in the SPIONs' spectra (grey lines). This indicates that the BSA coating was successful.

AFM analysis of silica nanoparticles

AFM analysis of silica nanoparticles

(A) Example of analysis of an AFM image of silica nanoparticles. The grain analysis method was used to identify isolated nanoparticles (coloured), whose maximal height was measured and used as a measurement of their diameter. Clusters of nanoparticles and nanoparticles located on the image edges have been excluded from the analysis. (B) Resulting histogram of the maximal nanoparticle height based on 1010 measurements. The number based modal particle size diameter (= max particle height) results (79 ± 5) nm. The uncertainty is calculated based on the method precision, repeatability, bias comprising contributions from the height calibration of the AFM scanner and from mechanical deformation of the tip-sample contact.

Imaging of 500 nm gold nanoparticles by Scanning Electron Microscopy (SEM)

Imaging of 500 nm gold nanoparticles by Scanning Electron Microscopy (SEM)

SEM images of 500 nm gold particles. Electron microscopy allow visualisation of the particles, which provides useful information about their sizes and shapes. Sample heterogeneities can be highlighted from this type of investigation.

Size distribution of silica nanoparticles by Electron Microscopy

Size distribution of silica nanoparticles by Electron Microscopy

Representative (a) Scanning Electron Microscopy (SEM) In-Lens and (c) Scanning Transmission Electron Microscopy (STEM) images of silica nanoparticles. Image size 3.770 µm x 2.828 µm. To note that the images were acquired on the same sample area. The relative histograms are shown respectively in figures (b) and (d). For these histograms, a total of 6,799 nanoparticles were analysed. The resulting number based modal nanoparticle diameters were (88.1 ± 2.4) nm and (88.5 ± 5.4) nm for the SEM and STEM techniques respectively.

Last Updated: 10 Mar 2016
Created: 8 Dec 2010

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