Development of a sample preparation approach to measure the size of nanoparticle aggregates by electron microscopy

Agnieszka Dudkiewicz*, Angela Lehner, Qasim Chaudhry, Kristian Mølhave, Guenter Allmaier, Karen Tiede, Alistair B.A. Boxall, Peter Hofmann, John Lewis

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Electron microscopy (EM) is widely used for nanoparticle (NP) sizing. Following an initial assessment of two sample preparation protocols described in the current literature as “unperturbed”, we found that neither could accurately measure the size of NPs featuring a broad size distribution, e.g., aggregates. Because many real-world NP samples consist of aggregates, this finding was of considerable concern. The data showed that the protocols introduced errors into the measurement by either inducing agglomeration artefacts or providing a skewed size distribution towards small particles (skewing artefact). The focus of this work was to develop and apply a mathematical refinement to correct the skewing artefact. This refinement provided a much improved agreement between EM and a reference methodology, when applied to the measurement of synthetic amorphous silica NPs. Further investigation, highlighted the influence of NP chemistry on the refinement. This study emphasised the urgent need for greater and more detailed consideration regarding the sample preparation of NP aggregates to routinely achieve accurate measurements by EM. This study also provided a novel refinement solution applicable to the size characterisation of silica and citrate-coated gold NPs featuring broad size distributions. With further research, this approach could be extended to other NP types.
Original languageEnglish
JournalParticuology
Volume45
Pages (from-to)49-57
ISSN1674-2001
DOIs
Publication statusPublished - 2019

Keywords

  • Nanoparticles
  • Aggregates
  • Measurement
  • Electron microscopy
  • Sample preparation
  • Artefacts

Cite this

Dudkiewicz, Agnieszka ; Lehner, Angela ; Chaudhry, Qasim ; Mølhave, Kristian ; Allmaier, Guenter ; Tiede, Karen ; Boxall, Alistair B.A. ; Hofmann, Peter ; Lewis, John. / Development of a sample preparation approach to measure the size of nanoparticle aggregates by electron microscopy. In: Particuology. 2019 ; Vol. 45. pp. 49-57.
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title = "Development of a sample preparation approach to measure the size of nanoparticle aggregates by electron microscopy",
abstract = "Electron microscopy (EM) is widely used for nanoparticle (NP) sizing. Following an initial assessment of two sample preparation protocols described in the current literature as “unperturbed”, we found that neither could accurately measure the size of NPs featuring a broad size distribution, e.g., aggregates. Because many real-world NP samples consist of aggregates, this finding was of considerable concern. The data showed that the protocols introduced errors into the measurement by either inducing agglomeration artefacts or providing a skewed size distribution towards small particles (skewing artefact). The focus of this work was to develop and apply a mathematical refinement to correct the skewing artefact. This refinement provided a much improved agreement between EM and a reference methodology, when applied to the measurement of synthetic amorphous silica NPs. Further investigation, highlighted the influence of NP chemistry on the refinement. This study emphasised the urgent need for greater and more detailed consideration regarding the sample preparation of NP aggregates to routinely achieve accurate measurements by EM. This study also provided a novel refinement solution applicable to the size characterisation of silica and citrate-coated gold NPs featuring broad size distributions. With further research, this approach could be extended to other NP types.",
keywords = "Nanoparticles, Aggregates, Measurement, Electron microscopy, Sample preparation, Artefacts",
author = "Agnieszka Dudkiewicz and Angela Lehner and Qasim Chaudhry and Kristian M{\o}lhave and Guenter Allmaier and Karen Tiede and Boxall, {Alistair B.A.} and Peter Hofmann and John Lewis",
year = "2019",
doi = "10.1016/j.partic.2018.05.007",
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Dudkiewicz, A, Lehner, A, Chaudhry, Q, Mølhave, K, Allmaier, G, Tiede, K, Boxall, ABA, Hofmann, P & Lewis, J 2019, 'Development of a sample preparation approach to measure the size of nanoparticle aggregates by electron microscopy', Particuology, vol. 45, pp. 49-57. https://doi.org/10.1016/j.partic.2018.05.007

Development of a sample preparation approach to measure the size of nanoparticle aggregates by electron microscopy. / Dudkiewicz, Agnieszka; Lehner, Angela; Chaudhry, Qasim; Mølhave, Kristian; Allmaier, Guenter; Tiede, Karen; Boxall, Alistair B.A.; Hofmann, Peter; Lewis, John.

In: Particuology, Vol. 45, 2019, p. 49-57.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Development of a sample preparation approach to measure the size of nanoparticle aggregates by electron microscopy

AU - Dudkiewicz, Agnieszka

AU - Lehner, Angela

AU - Chaudhry, Qasim

AU - Mølhave, Kristian

AU - Allmaier, Guenter

AU - Tiede, Karen

AU - Boxall, Alistair B.A.

AU - Hofmann, Peter

AU - Lewis, John

PY - 2019

Y1 - 2019

N2 - Electron microscopy (EM) is widely used for nanoparticle (NP) sizing. Following an initial assessment of two sample preparation protocols described in the current literature as “unperturbed”, we found that neither could accurately measure the size of NPs featuring a broad size distribution, e.g., aggregates. Because many real-world NP samples consist of aggregates, this finding was of considerable concern. The data showed that the protocols introduced errors into the measurement by either inducing agglomeration artefacts or providing a skewed size distribution towards small particles (skewing artefact). The focus of this work was to develop and apply a mathematical refinement to correct the skewing artefact. This refinement provided a much improved agreement between EM and a reference methodology, when applied to the measurement of synthetic amorphous silica NPs. Further investigation, highlighted the influence of NP chemistry on the refinement. This study emphasised the urgent need for greater and more detailed consideration regarding the sample preparation of NP aggregates to routinely achieve accurate measurements by EM. This study also provided a novel refinement solution applicable to the size characterisation of silica and citrate-coated gold NPs featuring broad size distributions. With further research, this approach could be extended to other NP types.

AB - Electron microscopy (EM) is widely used for nanoparticle (NP) sizing. Following an initial assessment of two sample preparation protocols described in the current literature as “unperturbed”, we found that neither could accurately measure the size of NPs featuring a broad size distribution, e.g., aggregates. Because many real-world NP samples consist of aggregates, this finding was of considerable concern. The data showed that the protocols introduced errors into the measurement by either inducing agglomeration artefacts or providing a skewed size distribution towards small particles (skewing artefact). The focus of this work was to develop and apply a mathematical refinement to correct the skewing artefact. This refinement provided a much improved agreement between EM and a reference methodology, when applied to the measurement of synthetic amorphous silica NPs. Further investigation, highlighted the influence of NP chemistry on the refinement. This study emphasised the urgent need for greater and more detailed consideration regarding the sample preparation of NP aggregates to routinely achieve accurate measurements by EM. This study also provided a novel refinement solution applicable to the size characterisation of silica and citrate-coated gold NPs featuring broad size distributions. With further research, this approach could be extended to other NP types.

KW - Nanoparticles

KW - Aggregates

KW - Measurement

KW - Electron microscopy

KW - Sample preparation

KW - Artefacts

U2 - 10.1016/j.partic.2018.05.007

DO - 10.1016/j.partic.2018.05.007

M3 - Journal article

VL - 45

SP - 49

EP - 57

JO - Particuology

JF - Particuology

SN - 1674-2001

ER -