Colloid and Polymer Science

, Volume 264, Issue 12, pp 1005–1009

Zeta potential and surface charge density of polystyrene-latex; comparison with synaptic vesicle and brush border membrane vesicle


  • K. Ohsawa
    • Department of Physiology, Faculty of MedicineUniversity of Tokyo
  • M. Murata
    • Central Scientific CommerceInc. Tokyo
  • H. Ohshima
    • Department of Biophysical ScienceState University of New York at Buffalo
Polymer Science

DOI: 10.1007/BF01410317

Cite this article as:
Ohsawa, K., Murata, M. & Ohshima, H. Colloid & Polymer Sci (1986) 264: 1005. doi:10.1007/BF01410317


The electrophoretic mobility of polystyrene — latex (PSL) of diameter 870 Å was determined using a Laser Zee System 3000. This instrument enables automatic measurement of the electrophoretic mobility of fine particles. Effect of pH and ionic strengthI on the PSL mobility was analyzed. It was found that the mobility as a function of pH has a minimum around pH 3–4 atI=0.1, showing no isoelectric point, and that the mobility decreases with increasing ionic strength up toI=0.1 but is almost constant forI=0.1–0.2 at pH=7.34. From the mobility date, we estimated the zeta potentialζ of PSL. We used an approximate mobility formula derived by Ohshima, Healy and White, which is considerably more accurate than Smolchowski's and Henry's formula and is applicable for fine particles with smallχ a (χ a≳10), whereχ is the Debye-Hückel parameter anda is the particle radius. Further, we calculated the surface charge densityσ of PSL using an approximateσζ relationship. It was found that there are 2000–4000 negative charges on the PSL surface at pH=7.34. Comparison is made with the results on synaptic vesicles (SV) from brain cerebrum cortex and brush-border-membrane vesicles (BBMV) from the small intestine.

Key words

Zeta potentialsurface charge densitypolystyrene latexsynaptic vesiclebrush border membrane
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© Steinkopff 1986