Zeta Potential

Zeta Potential refers to the electrical potential at the boundary between a particle surface and the surrounding liquid medium, representing a key indicator of colloidal stability in suspensions such as nanoparticles, liposomes, emulsions, and protein aggregates. It reflects the degree of electrostatic repulsion or attraction between particles, influencing whether they remain dispersed or undergo aggregation. Higher absolute zeta potential values generally indicate stronger repulsive forces reducing particle clustering, while low absolute values suggest increased instability.

In biopharmaceutical development, zeta potential measurement is essential for characterising nanocarriers, vaccine delivery systems, and injectable formulations where stability, consistency, and safety depend on controlled particle behaviour. Formulation scientists adjust zeta potential through pH changes, buffer composition, ionic strength, and surface modifications such as PEGylation or ligand attachment. Zeta potential also influences biodistribution and cellular uptake, as surface charge affects interactions with membranes, serum proteins, and immune clearance mechanisms. Analytical methods such as electrophoretic light scattering are commonly used to quantify zeta potential during formulation optimisation and quality control. As nanomedicine expands and complex delivery systems become more common, zeta potential remains a critical parameter supporting product performance, stability, and regulatory compliance.