Characterization of Nanoparticle Delivery Systems Using TEM

Jim Naumann, NanoImaging Services


Nanoparticle delivery systems (e.g. liposomes, polymeric micelles) pose challenges for characterization that require an interdisciplinary approach in which several orthogonal methods are required to provide a complete picture. Cryo‐electron microscopy (cryoEM), with its unique capability for visualizing samples in their natural hydrated state, is a powerful new tool in the armamentarium of characterization techniques applied to nanoparticles. CryoEM provides snapshots of particles suspended in their aqueous medium, and avoids the artifacts associated with other methods of TEM preparation (e.g. negative stain and freeze fracture). CryoEM images provide for characterization  size, shape, morphology, lamellarity, state of preservation, and degree of aggregation, and also provides for direct observa'on of the interaction of cargo and adjuvants. Quantitative metrics extracted from the images can be tracked on a particle‐by‐particle basis providing a direct method for understanding the metrics. The images are also very powerful tools in helping to interpret data from other, more indirect but orthogonal, methods.