FIGURE 5.

The effect of pH and buffer content on the EM of AMSC‐derived small EVs. (a) Measured EM of the isolated EV‐enriched fraction at various pH conditions (ionic strength of 14 mM). Small EVs are negatively charged structures under basic conditions (corresponding to a negative EM), while transforming toward a more positive structure as electrolyte acidity is increased. (b) Measured EM of small EVs (collected from 3 mL culture supernatant) in diluted PBS with ionic strength of ∼20 mM and ∼14 mM (pH∼7.5). In an electrolyte with lower ionic strength (14 mM), small EVs exhibited a larger magnitude of EM, accounting for a greater surface charge. (c) Measured EM for small EVs dispersed in diluted PBS with ionic strength of 14 mM (pH∼7.5). Two EV groups were experimentally tested; the first contained small EVs collected from 3 mL of culture supernatant (EV. 3X) and the second from 6 mL of culture supernatant (EV. 6X). Particle dispersions with lower particle concentration represented a greater magnitude of EM and accordingly a greater surface charge. **p‐value < 0.01, ***p‐value < 0.001.