Transmission Electron Microscopy as a Tool for the Characterization of Soft Materials: Application and Interpretation

Abstract

Transmission electron microscopy (TEM) provides direct structural information on nano‐structured materials and is popular as a characterization tool in soft matter and supramolecular chemistry. However, technical aspects of sample preparation are overlooked and erroneous image interpretations are regularly encountered in the literature. There are three most commonly used TEM methods as we derived from literature: drying, staining and cryo‐TEM, which are explained here with respect to their application, limitations and interpretation. Since soft matter chemistry relies on a lot of indirect evidence, the role of TEM for the correct evaluation of the nature of an assembly is very large. Mistakes in application and interpretation can therefore have enormous impact on the quality of present and future studies. We provide helpful background information of these three techniques, the information that can and cannot be derived from them and provide assistance in selecting the right technique for soft matter imaging. This essay warns against the use of drying and explains why. In general cryo‐TEM is by far the best suited method and many mistakes and over‐interpretations can be avoided by the use of this technique.

A Tethered Vesicle Assay for High-Throughput Quantification of Membrane Fission

“…Finally, while TEM experiments quantify the diameters of fission products, they typically rely on manual analysis of vesicles in electron micrographs (Boucrot et al, 2012). This approach greatly limits throughput and can be biased by the selection of the field of view as well as insufficient understanding and control of vesicle adsorption and staining on TEM grids (Franken, Boekema, & Stuart, 2017). In light of these limitations, the development of novel assays that provide quantitative results in a high-throughput format is needed.…”

Triblock copolymers of styrene and sodium methacrylate as smart materials: synthesis and rheological characterization

“…Since negative stain TEM is limited in information and prone to over interpretation of the structure of soft materials such as hydrogels, the gel structure of entry 8 (PS75-PMAA629) was also investigated using cryo-transmission electron microscopy in order to have a more native view of the structure [40,41]. Cryo-TEM images of gels at different concentrations are displayed in Fig.…”

Light‐Triggered Transformation of Molecular Baskets into Organic Nanoparticles

“…Transmission electronic micrographs of 0.1 mm solution of 2 3À revealed the formation of circularo bjects with ad ark boundary resulting from the negative stain (Figure4E). [32] The diameter of these structures is circa 90 nm and somewhatsmaller than the size of particles detected with DLS. At last, cryo-TEMi maging of 2 3À (Fig- ure 4F)r evealed the formation of spherical nanoparticles having ad istribution of sizes, with large ones being 80 nm in diameter and without ad istinct boundary to depict av esicular double-layer.…”

“…Dynamic light scattering (DLS) measurements of 1.0 m m solution of 2 3− showed a single peak centered at 180 nm (Figure D) to indicate the formation of particles having hydrodynamic diameter D H =20(±25) nm and a narrow distribution of sizes (PDI=0.25). Transmission electronic micrographs of 0.1 m m solution of 2 3− revealed the formation of circular objects with a dark boundary resulting from the negative stain (Figure E) . The diameter of these structures is circa 90 nm and somewhat smaller than the size of particles detected with DLS.…”