The point at which the zeta potential becomes zero (surface potential of the particle becomes zero) is called the isoelectric point. Colloid particles lose their electrostatic repulsion to aggregate if the pH approaches the isoelectric point. To stabilize dispersion states, we must keep pH far from the isoelectric point to rise the absolute value of the zeta potential.
We measured the pH dependence of particle diameter and the zeta potential of liposomes (Liposome KIT L-ɑ-Phosphatidylcholine [egg yolk] for positively charged liposome from Sigma).
