![]() ![]() The physical and chemical properties of a NM may be different from the properties of the corresponding bulk material because of quantum and surface effects which are size dependent. For aggregates and agglomerates, these particles are referred to as primary particles. These particles are minute pieces of matter with defined physical boundaries. The regulatory definition of a NM was and is an issue of debate, but it is agreed that a NM contains a relevant fraction of unbound, aggregated or agglomerated particles with one or more external dimensions in the size range of one to 100 nm. The presented method allows a detailed quantitative characterization of NM, like dispersions of precipitated and pyrogenic SAS based on the number-based distributions of their mean diameter, sphericity and shape factor. Using principle component analysis (PCA), twenty-three measured parameters were classified into three classes containing measures for size, shape and surface topology of the NM. Access to multiple parameters further allows selecting the optimal parameter in function of a specific purpose. This reduces operator-induced bias and assures a statistically relevant number of measurements, avoiding the tedious repetitive task of manual measurements. Automation allows measuring multiple and arithmetically complex parameters simultaneously on high numbers of detected particles. Resultsīright field (BF) TEM combined with systematic random imaging and semi-automatic image analysis allows measuring the properties of SAS NM quantitatively. A method based on transmission electron microscopy (TEM), to visualize the NM and on image analysis, to measure detected features quantitatively, was assessed for its capacity to characterize the aggregates and agglomerates of precipitated and pyrogenic synthetic amorphous silicon dioxide (SAS), or silica, NM. The interaction of a nanomaterial (NM) with a biological system depends not only on the size of its primary particles but also on the size, shape and surface topology of its aggregates and agglomerates. ![]()
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