Nanoparticle size analysis
To measure the size and concentration of particles in each pEV sample, a microfluidic resistive pulse sensing device (Spectradyne nCS1, CA, USA) was used. For nanoparticle size analysis, the isolated pEV sample was diluted to 1:20 with PBST, and 5 μL was aliquoted into a TS‐400 cartridge (measurement range 50–400 nm). Spectradyne acquisition time was set at 10 s. The first acquisition of each sample was excluded from processing. Datasets for each sample were collected until the apparent error of the particle analysis was less than 0.5% based on the default processing conditions.Diameter correction factor was determined by the analysis of three size standards. To cover the expected pEV size range, National Institute of Standards and Technology traceable particle size monodisperse polystyrene beads of 92.8, 150, and 208 nm size were used as a mixture. The standard mix was run on the same chipset as the samples analysed. Post‐processing of the data was conducted, which included the subtraction of background particles (20 nm filtered PBST). Default size and transit time filters were added to exclude data points from the diluent buffer and electronic noise. The area under the curve calculations was conducted (Viewer software, Spectradyne, CA, USA) to determine the concentration of particles within selected size ranges.