Freeze Fracture Direct Imaging:  A New Freeze Fracture Method for Specimen Preparation in Cryo-Transmission Electron Microscopy

Abstract

In this paper, we present a new freeze fracture method for specimen preparation for transmission electron microscopy frozen samples. We call it freeze fracture direct imaging (FFDI) because it is a hybrid of conventional freeze fracture electron microscopy (FFEM) and cryo-transmission electron microscopy (cryo-TEM), combining elements of the fracture technique with direct imaging. Like in FFEM, the sandwich method is used to prepare the sample in a protected fashion. However, after the sample is vitrified and fractured, it is not shadowed but directly imaged. The new technique avoids some experimental artifacts produced by the blotting procedure in conventional cryo-TEM. It relies, though, on occasional fractures transparent to the electrons. The advantageous features are demonstrated by a comparison between conventional cryo-TEM and FFDI micrographs of vesicular solutions. The second outstanding advantage over conventional cryo-TEM is the fact that it is now possible for the very first time to directly image oil-rich mixtures films which normally would dissolve in the cryo-medium ethane. Micrographs of pure oil and of oil-rich microemulsions clearly prove the reliability of the FFDI technique as well as its enormous potential.

Progress in liquid crystalline dispersions: Cubosomes

“…Nevertheless, the areas discussed above are just a few of the potential applications of cubosomes where microscopy could directly address unknowns. Other areas of potential include a re-examination of the key conclusions of the last 20 years using the new Freeze Fracture Direct Imaging techniques [58] that avoids some of the artifacts associated with cryo-TEM and FF-TEM. Finally, the rheological and flow behavior of cubic phases is at the core of their uniqueness, but few fundamental studies exist that link the flow, deformation, and hydrodynamic behavior of cubosome dispersions with their structure and performance.…”

Transmission electron microscopy in formation and growth of ordered mesoporous materials

“…In cases where particles from the reagent solution have been imaged after drying there is the possibility of artefacts being induced in the drying process by an ad hoc EISA process. With cryo-TEM there are other problems regarding sample preparation [17][18][19] such as for example shear induced structural transitions. To conclude, it seems that relying on electron microscopy data alone, either by conventional TEM or by cryo-TEM may be deceptive.…”

Phase diagrams of microemulsions containing reducing agents and metal salts as bases for the synthesis of metallic nanoparticles

“…Not surprisingly, SANS measurements at the water emulsification failure boundary can also be interpreted in terms of spherical water-swollen micelles interacting through a hard sphere potential [35,36,40]. A further proof of the spherical nature of water droplets at the wefb was obtained via transmission electron microscopy [41]. The diameter d of the spherical droplets at the wefb can be calculated according to…”