Reproducible extracellular vesicle size and concentration determination with tunable resistive pulse sensing

Coumans, Frank AW, Edwin van der Pol, Anita N. Böing, Najat Hajji, Guus Sturk, Ton G. van Leeuwen, and Rienk Nieuwland. "Reproducible extracellular vesicle size and concentration determination with tunable resistive pulse sensing." Journal of extracellular vesicles 3, no. 1 (2014): 25922.

Introduction: The size of extracellular vesicles (EVs) can be determined with a tunable resistive pulse sensor
(TRPS). Because the sensing pore diameter varies from pore to pore, the minimum detectable diameter also
varies. The aim of this study is to determine and improve the reproducibility of TRPS measurements.
Methods: Experiments were performed with the qNano system (Izon) using beads and a standard urine vesicle
sample. With a combination of voltage and stretch that yields a high blockade height, we investigate whether
the minimum detected diameter is more reproducible when we configure the instrument targeting (a) fixed
stretch and voltage, or (b) fixed blockade height.
Results: Daily measurements with a fixed stretch and voltage (n102) on a standard urine sample show
a minimum detected vesicle diameter of 128919 nm [mean9standard deviation; coefficient of variation
(CV) 14.8%]. The vesicle concentration was 2.410993.8109 vesicles/mL (range 1.41081.81010). When we
compared setting a fixed stretch and voltage to setting a fixed blockade height on 3 different pores, we found a
minimum detected vesicle diameter of 118 nm (CV 15.5%, stretch), and 123 nm (CV 4.5%, blockade height).
The detected vesicle concentration was 3.28.2108 vesicles/mL with fixed stretch and 6.47.8108 vesicles/mL
with fixed blockade height.
Summary/conclusion: Pore-to-pore variability is the cause of the variation in minimum detected size when
setting a fixed stretch and voltage. The reproducibility of the minimum detectable diameter is much improved
by setting a fixed blockade height.

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