Characterization of nanoparticles under physiological conditions

In this article, well-established characterization methods for nanoparticles (NPs) are discussed, in particular their application under physiological conditions. The impact of different media, mimicking physiological conditions, on NP stability in terms of physiological ionic strength and formation of the NP-protein corona is described. In order to characterize NPs under physiological conditions, we distinguish between scattering and correlation methods, microscopy-based methods, and methods based on hydrodynamic separation. Features and limitations of relevant characterization methods are reviewed, as well as challenges arising in physiological media from enhanced aggregation tendency and the presence of proteins. We conclude that no available method for NP characterization in physiological media is able to describe the colloidal system completely and satisfactory. On the contrary, combining well-chosen analytical methods by taking benefits and disadvantages into account may provide detailed characterization results.