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- Minelli, Caterina, et al.
(author)
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Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles
- 2022
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In: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 14, s. 4690-4704
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Journal article (peer-reviewed)abstract
- We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles.
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2. |
- Pacurar, Daniel I., et al.
(author)
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Agrobacterium tumefaciens : From crown gall tumors to genetic transformation
- 2011
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In: Physiological and molecular plant pathology. - London : Academic Press. - 0885-5765 .- 1096-1178. ; 76:2, s. 76-81
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Research review (peer-reviewed)abstract
- The phytopathogenic bacterium Agrobacterium tumefaciens is the causative agent of crown gall disease on a broad range of plant species. For more than a century this pathogen has fascinated biologists for various reasons. It has been believed that disclosing the mystery of the crown gall tumour disease in plants might help to understand the mechanisms of oncogenesis in general, and eventually use this knowledge to cure cancer in animals and humans. However, as the performer of the only known case of trans-kingdom DNA transfer, this natural genetic engineer is recognised by nowadays biologists particularly for this feature, and Agrobacterium-mediated genetic transformation has become the preferred method to generate transgenic plants. This review briefly highlights the key steps in DNA transfer during natural A. tumefaciens infection and the subsequent development of crown gall disease. It will focus on the adaptation and use of this proof of principle for the purpose of genetic transformation. (C) 2011 Elsevier Ltd. All rights reserved.
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