TABLE 1.
Comparison of different theoretical approximations to estimate the electrical properties of small EVs and HSA proteins according to their measured EM.
| Mean zeta potential (mV) | Mean electrical valence | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Particle sample | pH | Κa Value (nm−1) | Mean measured EM (μm.cm.V−1.s−1) | Smoluchowski | Hückel | Ohshima | Surface charge density (C.nm−2) ✗10−21 | Zeff | ZDHH | ZOhshima |
| HSA protein | ∼3.5 | 1.36 | +0.10 | +1.3 | +0.9 | +1.9 | 0.9 | +0.4 | +1.3 | +0.8 |
| ∼4.5 | 1.36 | ‐0.20 | ‐2.6 | ‐1.7 | ‐3.7 | 1.7 | ‐0.7 | ‐2.5 | ‐1.6 | |
| ∼7.5 | 1.36 | ‐1.26 | ‐13.8 | ‐9.2 | ‐19.8 | 9.3 | ‐3.95 | ‐13.4 | ‐8.9 | |
| ∼10.5 | 1.36 | ‐1.34 | ‐15.9 | ‐10.6 | ‐22.7 | 10.7 | ‐4.5 | ‐15.4 | ‐10.3 | |
| Isolated small EVs | ∼4.5 | 33.02 | +0.32 | +4.1 | +2.7 | +4.3 | 1.2 | +28.1 | +1023.5 | +675.6 |
| ∼7.5 | 33.02 | ‐1.49 | ‐18.9 | ‐12.6 | ‐20.3 | 5.7 | ‐132 | ‐4808.1 | ‐3246.3 | |
| ∼10.5 | 33.02 | ‐2.30 | ‐29.3 | ‐19.5 | ‐31.4 | 9.2 | ‐204 | ‐7427.7 | ‐5183.8 | |
Note: The parameter κa was calculated according to the ionic strength of the buffer solution (14 mM) and hydrodynamic radius (a) of dispersed particles. In this study, HSA protein was considered to have an average hydrodynamic radius of 3.5 nm according to the literature values reported for the size of HSA protein. (Jachimska et al., 2008, Leggio et al., 2008, Armstrong et al., 2004) Hydrodynamic radius of small EVs was considered about 85 nm according to the size distribution depicted from DLS analysis in this study.