Inter-laboratory comparison on the size and stability of monodisperse and bimodal synthetic reference particles for standardization of extracellular vesicle measurements

Abstract

In future, measurements of extracellular vesicles in body fluids could become a standard diagnostic tool in medicine. For this purpose, reliable and traceable methods, which can be easily applied in hospitals, have to be established. Within the European Metrological Research Project (EMRP) 'Metrological characterization of micro-vesicles from body fluids as noninvasive diagnostic biomarkers' (www.metves.eu), various nanoparticle reference materials were developed and characterized. We present results of an international comparison among four national metrology institutes and a university hospital. The size distributions of five monodisperse and two bimodal spherical particle samples with diameters ranging from 50 nm to 315 nm made out of silica and polystyrene were compared. Furthermore, the stability of the samples was verified over a period of 18 months. While monodisperse reference particle samples above a certain size level lead to good agreements of the size measurements among the different methods, small and bimodal samples show the limitations of current 'clinical' methods. All samples proved to be stable within the uncertainty of the applied methods.

Validation of a particle tracking analysis method for the size determination of nano- and microparticles

“…Also, the modal values of the PSDs were significantly larger than the certified (42.1 nm for DLS) and indicative (27.8 nm for electron microscopy) values. Similar observations were recently made by Tuoriniemi et al ( 2014 ) and Nicolet et al ( 2016 ) who reported biased PTA results of about 67 nm and 87 nm for silica nanoparticles of nominally 35 nm and 48 nm in diameter, respectively. Nicolet et al suggested that the systematic error was due to the method’s insensitivity to the small particles in the sample and the counting of particle clusters instead.…”

Methodological Guidelines to Study Extracellular Vesicles

“…Furthermore, clinical applications of single EV methods also require standards and calibrators to ensure reproducibility and comparability of measurement results across laboratories and over time. 105,106 The selection or development of a single EVs detection method requires knowledge on the physical properties of EVs. Platelet-free plasma contains spherical EVs (>95%; 50 nm to 1 µm in diameter), tubular EVs (<5%, 1-to 5-µm long), and membrane fragments (<0.5%, 1-8 µm in diameter).…”

Measuring particle concentration of multimodal synthetic reference materials and extracellular vesicles with orthogonal techniques: Who is up to the challenge?

“…Being aware that each platform has differing strengths and limitations, multiple studies have been conducted to compare various methods for the characterization of nanoparticles generally, and EVs more specifically. Most studies have limited their focus on the study of PSD (Clénet et al., 2018; Lamberty et al., 2011; Langevin et al., 2018; Meli et al., 2012; Nicolet et al., 2016; Varenne et al., 2016), and only a few have compared the capability of multiple techniques to measure total particle concentration. Vestad et al.…”