Khaliq Brown

Hydrodynamic size and zeta potential of nanoparticles (NPs) are key parameters characterizing nanoparticles suspended in liquid, which is important in applications like  drug delivery, colloid stability, formulation optimization, and surface modification. We present measured size and zeta potential by Dynamic Light Scattering (DLS) and Electrophoretic Light Scattering (ELS) with surfactants of various concentration added to cuvette. DLS operates by analyzing fluctuations in the intensity of light scattered by NPs undergoing Brownian motion while ELS adds the electrostatic force to the motion. The Stokes-Einstein equation is used to calculate the hydrodynamic radius of the particles. The surfactant may affect the motion of nanoparticles suspended in liquid so their size and zeta potential can be measured differently as surfactant may change the solvent viscosity, resulting in different NP motion, which makes size measured differently. For example, faster motion also enhances the interactions between NPs, which may affect zeta potential. Our DLS data suggests that the size is measured differently with the surfactant concentration. In this talk, we present how surfactants influence the measurements of the hydrodynamic size and zeta potential of colloidal NPs that are synthesized at Grambling by laser ablation in liquid as well as commercial ones.