By BioNanoNet
Nanoparticles are commonly used for various pharmaceuticals and beauty products in order to influence the products’ properties, e.g. stability, consistency, appearance. As far as sun blockers are concerned public awareness regarding the safety of sunscreens containing nanoparticles, namely zinc oxide (ZnO) and titanium oxide (TiO2), has been increasing. Nanoparticles are used as protective agents against harmful ultraviolet (UV) radiation. Their small size ranging from 30 – 100 nm comes into play to avoid several unfavourable characteristics of sunscreens, e.g. difficulty in application and leaving white residue on the skin. Shape and size of nanoparticles are often unknown. Standardised transmission electron microscopy is amongst the best tools to get useful insight into the variety of used nanoparticles (size, shape, distribution, special treatment e.g. coatings, further additives). To analyse the chemical composition all TEMs installed at the ZFE Graz have the necessary analytical equipment (EDX and imaging filter). The method of choice is Electron Filtering Transmission Electron Microscopy (EFTEM), which is based on the interaction of fast primary electrons with atoms of the a few nanometres thin sample. The energy loss of these electrons is detected and serves as “finger print” giving away the chemical elements of the sample. Reference publication: (1) Haberfehlner, Georg, et al. “Nanoscale voxel spectroscopy by simultaneous EELS and EDS tomography.” Nanoscale 6.23 (2014): 14563-14569.
