Logo of the Physikalisch-Technische Bundesanstalt

Hollow nanospheres as potential reference particles for extracellular vesicles


Image: Transmission electron microscopy image of a HOB sample

Extracellular vesicles (EVs) are nanometer-sized cell-derived particles in body fluids and can be used as potential biomarkers for diseases such as cancer, inflammation and cardiovascular disease. EVs gained a lot of interest as they are released from all cell types and their biochemical composition, concentration and function are disease-dependent. The concentration and size distribution of EVs in body fluids such as blood or urine can be determined using optical measurement methods. The widely applied method of flow cytometry measures the scattering of light by the EVs in the sample . Until now, however, it has not been possible to derive the size and concentration of the particles with sufficient accuracy.

As part of the metrology research project "METVES II", a consortium of European metrology institutes has investigated nanoscale hollow organosilica beads (HOBs) as reference materials, which are very similar to EVs regarding their optical properties ,and therefore suitable for calibrating optical measuring instruments. By using monochromatised synchrotron radiation, PTB has contributed to the accurate size characterisation of HOBs in its laboratory at BESSY II using small-angle X-ray scattering (SAXS). For the first time, the size and concentration of such particles could now be determined metrologically traceable to the international system of units (SI). By varying the thickness of their silicon dioxide shell, HOBs with highly variable optical properties and in many sizes can be synthesised and reference particles adapted to a wide variety of EVs can be produced.


J. Deumer et al., Discover Nano 19, 14 (2024), https://doi.org/10.1186/s11671-024-03956-3


J. Deumer, 7.21, e-mail: jerome.deumer(at)ptb.de