Extracellular vesicles
(EVs), including exosomes and microvesicles
(<200 nm), play a vital role in intercellular communication and
carry a net negative surface charge under physiological conditions.
Zeta potential (ZP) is a popular method to measure the surface potential
of EVs, while used as an indicator of surface charge, and colloidal
stability influenced by surface chemistry, bioconjugation, and the
theoretical model applied. Here, we investigated the effects of such
factors on ZP of well-characterized EVs derived from the human choriocarcinoma
JAr cells. The EVs were suspended in phosphate-buffered saline (PBS)
of various phosphate ionic concentrations (0.01, 0.1, and 1 mM), with
or without detergent (Tween-20), or in the presence (10 mM) of different
salts (NaCl, KCl, CaCl
2
, and AlCl
3
) and at different
pH values (4, 7, and 10) while the ZP was measured. The ZP changed
inversely with the buffer concentration, while Tween-20 caused a significant
(
p
< 0.05) lowering of the ZP. Moreover, the ZP
was significantly (
p
< 0.05) less negative in
the presence of ions with higher valency (Al
3+
/Ca
2+
) than in the presence of monovalent ones (Na
+
/K
+
). Besides, the ZP of EVs became less negative at acidic pH, and
vice versa
. The integrated data underpins the crucial role
of physicochemical attributes that influence the colloidal stability
of EVs.
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