Light Scattering Characterization of Anisotropic Nanoparticles

Depolarized dynamic light scattering (DDLS) can be used to measure the rotational and translational diffusion of nanoparticles suspended in solution. The particle size, shape, diffusion, and interactions can then be inferred from the DDLS data using various models of diffusion. Incorporating the technique of DDLS to analyze the dimensions of easily imaged elongated particles, such as Iron (III) oxyhydroxide (FeOOH) spindles and gold nanorods, allows testing of the models for rotational and translational diffusion of elongated particles in solution. This study can further be used to help better interpret DDLS data on hard-to-image anisotropic soft matter systems such as micelles, microgels, and protein complexes. This study focused on FeOOH Spindles and gold nanorod particles. The light scattering results on spindles using the basic model of non-interacting prolate ellipsoids yielded results within 17% of the SEM measured dimensions. The dimensions of gold nanorod obtained from the straight cylinder model of DDLS data provided results that varied depending on the solvent used and the aspect ratio.