Abstract
The physicochemical characterization of nanomaterials (NMs) is often an analytical challenge, due to their small size (at least one dimension in the nanoscale, i.e. 1-100 nm), dynamic nature, and diverse properties. At the same time, reliable and repeatable characterization is paramount to ensure safety and quality in the manufacturing of NM-bearing products. There are several methods available to monitor and achieve reliable measurement of nanoscale-related properties, one example of which is Ultraviolet-Visible Spectroscopy (UV-Vis). This is a well-established, simple, and inexpensive technique that provides non-invasive and fast real-time screening evaluation of NM size, concentration, and aggregation state. Such features make UV-Vis an ideal methodology to assess the proficiency testing schemes (PTS) of a validated standard operating procedure (SOP) intended to evaluate the performance and reproducibility of a characterization method. In this paper, the PTS of six partner laboratories from the H2020 project ACEnano were assessed through an interlaboratory comparison (ILC). Standard gold (Au) colloid suspensions of different sizes (ranging 5-100 nm) were characterized by UV-Vis at the different institutions to develop an implementable and robust protocol for NM size characterization.
Highlights
Nanomaterials (NMs) have become popular due to their unique properties in the nanoscale (1 to 100 nm), which differ from the properties of their bulk counterparts, either due to size-related or quantum effects along with distinct reactivity, optical, thermal, electrical, and magnetic properties1, 2
Scanning/transmission electron microscopy (SEM/TEM) are techniques used to obtain high-resolution optical and compositional information of NMs; atomic force microscopy (AFM) provides nanoscale resolution in the vertical (z axis) dimension; and X-ray diffraction (XRD) provides information on the atomic structure of NMs; all these methods can only be used on dry samples[10, 11]
Techniques suitable for the characterization of NMs in liquid media include field flow fractionation (FFF), which allows the separation of large molecules, aggregates, and particles based on their size; dynamic light scattering (DLS); and nanoparticle tracking analysis (NTA)—two methods widely used to determine the size distribution profile of particles using Brownian motion —and ultraviolet-visible spectrophotometry (UV-Vis), which allows the assessment of NM characteristics such as size, aggregation state, and refractive index by a simple absorption measurement11, 12, 13
Summary
Quality and reproducibility in the synthesis and characterization of NMs are extremely important for quality assurance, and for the safe manufacture of nano-based products, especially due to the reactivity of NMs, notably in complex environments, where NM properties, such as size distribution and morphology, may undergo rapid changes , . Techniques suitable for the characterization of NMs in liquid media include field flow fractionation (FFF), which allows the separation of large molecules, aggregates, and particles based on their size; dynamic light scattering (DLS); and nanoparticle tracking analysis (NTA)—two methods widely used to determine the size distribution profile of particles using Brownian motion —and ultraviolet-visible spectrophotometry (UV-Vis), which allows the assessment of NM characteristics such as size, aggregation state, and refractive index by a simple absorption measurement11 , 12 , 13 All these techniques allow NM characterization, their performance is dependent on instrument setup, instrument-related differences, complex methodology for sample preparation, and the user’s level of expertise. An SOP was provided to all the involved laboratories to ensure the identical preparation of AuNP suspensions, evaluation, and reporting of results to contribute towards the development of an implementable and robust tiered approach in NM physicochemical characterization, data interpretation, and improvement of best practice protocols for industrial and regulatory needs[8 ]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
