ABSTRACT
Important advances are being made in characterization of soft nanoparticles as well both regulators and practitioners agree that the inherent flexibility and responsiveness of soft nanomaterials make them particularly challenging targets for robust and unambiguous measurements. Among various complex nanomaterials, solid-core nanoparticles benefit from availability and applicability of some of the most advanced nanocharacterization techniques, many of which have been adapted from the decades of extensive research on characterization of solid nanoparticles. The practical caveats of using electron microscopy for nanocharacterization are related primarily to the widely acknowledged uncertainties and ambiguities arising from the preparation of representative samples, especially from polydisperse materials. Nanomaterials inherently have a much larger specific surface area than do bulk materials, so surfaces play a critical role in the interactions of nanoparticles with their environment and with each other. The regulatory consideration of soft nanoparticles to-date can be characterized as equivocal.
