Fig. 2

Reproducibility of density-based rEV separation by (in)experienced operators versus automated liquid handling. A Visualization of the accuracy in representative colored test gradients prepared by an inexperienced (inexp.), experienced (exp.), and automated operator (auto.) and the spilling of the 5% and 20% iodixanol solution in the 10% layer. B Density of the collected fractions obtained by manual (man.) versus automated density gradient centrifugation (fractions 7–12: n = 19,) as determined by 340 nm absorbance. C, D Recombinant EV (rEV) recovery (as quantified by the mean of fNTA and anti-p24 ELISA measurements) after bottom-up (BU) (n = 11) and top-down (TD) (n = 10) density gradient centrifugation by manual and automated liquid handling. E Inter-operator variability total and fraction-specific rEV recovery in after bottom-up density-based separation by (in)experienced operators versus automated liquid handling (n = 6). Total and fraction-specific rEV recovery after top-down density-based separation by (in)experienced operators versus automated liquid handling (n = 5) to compare F inter-operator, G intra-run and H inter-run variability. ***P < 0.001, **P < 0.01, *P < 0.05 (Mann–Whitney U test). °°P < 0.01, °P < 0.05 (F-test of equality of variances). Data in C, E, F, G, H are depicted as truncated violin plots. Data in D are depicted as histograms and accompanying gaussian curves. Source data are provided as Additional file 7: Table S1