Hydrodynamic diameter and zeta potential of nanostructured lipid carriers: Emphasizing some parameters for correct measurements

Particle size and zeta potential are basic information about nanoparticles intended for biomedical applications and other of scientific interest. Modern techniques for measuring these properties have become popular due to their simplicity and ease of use, but unfortunately, this has led to an inadequate understanding of the fundamental operational principles and physical meaning of the measured parameters. Consequently, the quality and interpretation of the reported data and the possibility to make comparisons between different studies are being questioned. As a contribution to this respect, this study stresses the importance of suitable experimental conditions to estimate the hydrodynamic diameter and the surface charge of lipid nanoparticles, specifically in nanostructured lipid carriers (NLC) stabilized by nonionic surfactants, by using dynamic light scattering and laser Doppler electrophoresis, respectively, to provide reliable information.