Nanomaterials are inherently polydispersed. Traditional techniques, such as the widely used batch-mode dynamic light scattering (DLS) analysis, are not ideal nor thoroughly descriptive enough to define the full complexity of these materials. Asymmetric-flow field-flow fractionation (AF4) with various in-line detectors, such as ultraviolet–visible (UV-Vis), multi-angle light scattering (MALS), refractive index (RI) and dynamic light scattering (DLS) is an alternative technique that can provide flow-mode analysis of not only size distribution, but also shape, drug release/stability, and protein binding [–3].